Noun and verb differences in picture naming: past studies and new evidence Simone Mätzig Judit Druks University College London Jackie Masterson Institute of Education, University of London Gabriella Vigliocco University College London Running title: Noun and verb differences Address for correspondence: Judit Druks, Division of Psychology and Linguistic Sciences, UCL, Chandler House, 2, Wakefield Street, London WCN1 1PF j.druks@ucl.ac.uk Tel: 020 7679 4261 Fax: 020 7679 4261 1 Abstract We re-examine the double dissociation view of noun-verb differences by critically reviewing past lesion studies reporting selective noun or verb deficits in picture naming, and reporting the results of a new picture naming study carried out with aphasic patients and comparison participants. Since there are theoretical arguments and empirical evidence that verb processing is more demanding than noun processing, in the review we distinguished between cases that presented with large and cases with small differences between nouns and verbs. We argued that the latter cases may be accounted for in terms of greater difficulty in processing verbs than nouns. For the cases reporting large differences between nouns and verbs we assessed consistency in lesion localization and consistency in diagnostic classification. More variability both in terms of diagnostic category and lesion sites was found among the verb impaired than the noun impaired patients. In the experimental study, nine aphasic patients and nine age matched neurologically unimpaired individuals carried out a picture naming study that used a large set of materials matched for age of acquisition and in addition to accuracy measures, latencies were also recorded. Despite the patients’ variable language deficits, diagnostic category and the matched materials, all patients performed faster and more accurately in naming the object than the action pictures. The comparison participants performed similarly. We also carried out a qualitative analysis of the errors patients made and showed that different types of errors were made in response to object and action pictures. We concluded that action naming places more and different demands on the language processor than object naming. 2 The conclusions of the literature review and the results of the experimental study are discussed in relation to claims previous studies have made on the basis of the double dissociation found between nouns and verbs. We argue that these claims are only justified when it can be shown that the impairments to the two categories occur for the same underlying reason and that the differences between the two categories are large. Key words: object and action naming, nouns and verbs, aphasia, double dissociation 3 Introduction On the basis of evidence from both language acquisition and language breakdown it was initially argued that the reason for verb deficits in aphasia and the delay in their acquisition is that verbs are more difficult to process than nouns. Later, however, reports that verbs are not always the impaired category, led to the claim that nouns and verbs are represented in distinct neural networks (e.g., Caramazza and Hillis, 1991; Damasio and Tranel, 1993; Daniele et al., 1994), and their selective impairment in different patient groups constitutes a double dissociation. In this paper we re-examine this view in light of past evidence and new data. The vocabulary of English and, probably, of other languages contains many more nouns than verbs, however, the token frequency of verbs is considerably higher than that of most nouns, and some verbs, for example, see, give, make, belong to the class of the most frequent words in the language. Despite the frequency differences in favour of verbs, verbs are known to be acquired somewhat later than nouns (e.g., Bassano, 2000; Bates et al., 1994; Caselli et al., 1995; Dromi, 1987; Fenson et al., 1994; Gentner, 1981, 1982; Masterson et al., 2008; Nelson, 1973; Stern, 1924). In addition to evidence from acquisition, aphasia researchers in the early 1980s argued that verbs are more vulnerable to brain damage due to their more complex grammatical status than that of nouns (e.g., Goodglass and Geschwind, 1976; Saffran et al., 1980; Saffran, 1982). These claims were supported by empirical studies that reported better performance for nouns than verbs in picture naming and other single word tasks (e.g., Bastiaanse and Jonkers, 1998; Berndt et al., 2002; Breedin and Martin, 1996; Breedin et al., 1998; Caramazza and Hillis, 1991; De Bleser and Kauschke, 2003; Hillis and Caramazza, 1995; Jonkers and Bastiaanse, 1996, 1998; 4 Kim and Thompson, 2000; Kohn et al., 1989; Shapiro and Caramazza, 2003a,b; Williams and Canter, 1987). Considering object and action labels only - the most widely investigated classes of nouns and verbs in the literature - there are a number of potential reasons why verbs might be more difficult than nouns. For example, the semantic representations of verbs have been considered to be more complex than those of nouns. Concrete nouns are organized into hierarchies of several levels, and exemplars of categories share many semantic features among themselves. Verbs, on the other hand, have a shallower semantic organization and less shared semantic features (e.g., Behrend, 1990; Huttenlocher and Lui, 1979; Vinson and Vigliocco, 2002). This property of verbs may render their processing more difficult, particularly for patients with semantic deficits. Moreover, verbs determine the number and type of arguments around them (e.g., Grimshaw, 2000). Different verbs have different argument structures, and some verbs have more than one permissible argument structure, resulting in subcategories of verbs, which makes generalising from the usage of one verb to another, often, impossible. This inherent property of verbs makes their acquisition difficult. In contrast, concrete nouns do not have an argument structure and, being usually count nouns, they tend to behave grammatically similarly to each other (e.g., they pluralize by adding –s, in the majority of cases), facilitating their early acquisition (e.g., Gleitman, 1993; Tomasello et al., 1997). For aphasia, Thompson and colleagues showed that verbs that have more arguments, and verbs that have more than one argument structure are more difficult to produce even in picture naming when the arguments themselves do not have to be produced (Kim and Thompson, 2000; Thompson, 2003). 5 Verbs also tend to be morphologically more complex than nouns in most languages (e.g., Vigliocco et al., 2006). This could lead to potential difficulties with verbs, in particular in aphasic patients and in children with developmental language disorders who have morpho-syntactic and/or morpho-phonological deficits. Finally, Bird and colleagues (Bird et al., 2000) highlight the fact that concrete verbs are rated as less imageable than concrete nouns. They argue that word class differences are due to the inherent imageability difference between nouns and verbs (e.g., Bird et al., 2003). Since imageability of (mainly) nouns is known to affect performance in word and picture naming, the relative low imageability of verbs may, arguably, affect their retrieval in all populations. In conclusion, any or all of the above semantic and syntactic differences between nouns and verbs may play a causal role in the later acquisition of verbs and their greater vulnerability in brain damage. However, the greater complexity of verbs over nouns does not explain the phenomenon of (some) anomic aphasics presenting with superior verb production in the face of impaired noun production (e.g., Berndt et al., 1997a; McCarthy and Warrington, 1985; Miceli et al., 1984, 1988; Zingeser and Berndt, 1990). These patients’ verb advantage, together with the verb deficits of Broca’s aphasic patients constitutes a double dissociation between noun and verb processing. Three distinct formulations of the double dissociation have been put forward. According to the first formulation, the dissociation is between nouns and verbs as lexical forms, that is grammatical class (e.g., Caramazza and Hillis, 1991; Hillis and Caramazza, 1995; Miceli et al., 1984, 1988; Zingeser and Berndt, 1990). This position implies that the critical difference between nouns and verbs applies not only to concrete nouns and verbs that are labels of objects and actions, but to abstract 6 nouns and verbs too. This prediction has not yet been extensively tested, though Berndt et al. (2002) found that for patients with relative verb deficits in picture naming, verb production was also impaired in a sentence completion task using abstract words. This study is problematic, however, because the performance of patients with relative noun deficits was not tested, and Collina et al. (2001), who compared the production of abstract nouns and verbs in Broca’s aphasic patients found no difference between them. Thus we still have no reliable evidence for similar performance patterns in processing concrete nouns and verbs and abstract nouns and verbs. A second formulation (Shapiro et al., 2000; Shapiro and Caramazza, 2003a, b) is that grammatical class differences emerge at the level of morphology. The claim is based on the finding that noun and verb deficits occur (in some patients) in conjunction with deficits of either nominal or verbal inflections. This position would imply that all patients with either noun or verb deficits should also present with (inflectional) morphological deficits selective to the category implicated, and patients with morphological deficits related to inflecting verbs and/or nouns should always present with lexical retrieval difficulties too in the relevant category. No such evidence is forthcoming. According to a third formulation, the dissociation is not between nouns and verbs per se, but between words referring to objects and words referring to actions or events. This position is made explicit in the work of Vigliocco and colleagues, who developed a model of the semantic representation of nouns and verbs on the basis of lists of (semantic) features generated by English speakers (Vinson and Vigliocco, 2002; Vigliocco et al., 2004). In the model, words referring to objects were clearly separated from words referring to actions, showing that the semantic makeup of 7 concrete nouns and verbs is different, and suggesting that a semantic impairment for objects or actions could easily be confused with a grammatical class deficit for either nouns or verbs if the test materials confounded the two, as in the case of all picture naming studies (see also Druks and Masterson, 2003; Vinson and Vigliocco, 2002 for discussion). Lesion, imaging and ERP studies support this formulation of the double dissociation to a large extent (e.g., Damasio and Tranel, 1993; Martin et al., 1995; Pulvermüller et al., 1999; Vigliocco et al., 2006). To date, in contrast to behavioural and lesion studies, imaging studies have been unable to provide evidence that is compatible with a double dissociation for nouns and verbs. In particular, either no difference was reported between word classes (Tyler et al., 2001; Vigliocco et al., 2006) or, verb specific activation (in left inferior frontal gyrus, IFG) was found in the absence of noun specific activation (Perani et al., 1999; Shapiro et al., 2001). The significance of the verb specific activation is not entirely clear, because left IFG is also implicated in decision and selection processes (Binder, 2004; Thompson-Schill, et al., 1997). Therefore, the hypothesis that verb-specific activation in this area is due to greater processing demands, and not due to verb processing per se, cannot be excluded. Thus, the puzzle of the underlying reason(s) for noun-verb differences, and their functional and neuroanatomical bases, remains to date unresolved. It is undeniable that there are patients who are more impaired in naming action pictures and using verbs, and other patients who are more impaired in naming object pictures and using nouns. The question, however, is how to account for the phenomenon of noun-verb differences that affect different patients differently, resulting, therefore, in a pattern of double dissociation. One route, which has been taken by the majority of the studies reviewed here, is that the empirical evidence of double dissociation itself allows the 8 making of theoretical claims in relation to the nature of noun-verb differences and their neuroanatomical representation. An alternative route is that the evidence of double dissociation constitutes descriptive data that requires further research and argumentation in order to uncover its theoretical significance. The reason why the second route is preferable is that complex categories of knowledge or complex processes may be impaired for different underlying reasons. Nouns and verbs, being such complex categories, consist of conceptual, semantic, syntactic, morphological and phonological features, and to use nouns and verbs, all these component features must become available. Moreover, some of these features might be essential for one category and not for the other. For example, certain types of grammatical knowledge might be essential for verb production but not for noun production, and certain types of visual-semantic knowledge, for (concrete) noun production but not for verb production. If this conception of nouns and verbs is plausible, noun-verb double dissociation must be considered as no more than a descriptive label of the attested noun-verb differences, unless it is shown that deficits to nouns in one patient type and deficits to verbs in a second patient type are due to the same underlying problem (i.e., morphological deficits or semantic deficits, for example). Otherwise it would be misleading to conclude on the basis of the evidence of double dissociation that nouns and verbs are represented in different and separable functional and anatomical loci, as it has been claimed in most relevant previous studies. In this study, we explore the phenomenon of noun-verb differences by, first, critically reviewing all lesion studies that report noun-verb dissociations in picture naming, and, second, by carrying out a new object-action picture naming study with a small group of aphasic patients with different clinical diagnoses and different severity levels. We expect that taking stock of previous findings from more than 25 years of 9 considerably intense research will enable us to reassess the strength of the evidence for double dissociation between noun and verb processing. Review of previous studies of noun-verb differences Given that the double dissociation between nouns and verbs discussed in the literature is based on patients’ picture naming performance, we included in the review only picture naming studies, and confined it to patients with focal brain damage. The studies included in the review were published between 1984 and 2005. We found 38 papers published during this period that compared the naming of object and action pictures in aphasic patients. The studies used different materials and different numbers of stimuli. The majority matched materials for frequency, fewer for length, and only some recent studies, for age of acquisition, familiarity or visual complexity. As for imageability, since concrete verbs are rated systematically lower in imageability than concrete nouns, none of the picture naming studies was able to match materials on this variable. Finally, a few studies did not match their noun and verb items at all1, and the large majority of studies did not report information about the level of name agreement for their stimuli. The studies are summarised in Table 1 which gives information about the number of patients participating in each study, their clinical diagnosis2, accuracy in naming objects and actions, and the magnitude of difference in favour of nouns or verbs. This was done for individual patients or, in the case of group studies when no information about the individual patients was available, for groups of patients. If the patients were tested in more than one naming task, average performance across all tasks is provided. Overall, we considered the performance of 280 patients. Forty (14%) patients did not show a noun-verb difference, 31 patients (11%) presented a 10 relative noun deficit, and 209 (75%) patients, a relative verb deficit. These numbers clearly show that relative verb deficits are more common than relative noun deficits. *****Table 1 is about here***** When the naming pattern of the 280 patients was compared with their clinical diagnosis, verb deficits were found to be associated with Broca’s aphasia, fluent aphasia and mixed aphasia, while relative noun deficits were confined to fluent type aphasia (with the exception of one Broca’s aphasic patient reported by Miceli et al. (1984) who presented with a small relative noun deficit). Further, it was found that a quarter of the Broca’s aphasic patients (n = 33) did not show any word class difference, and almost a quarter of the fluent type patients showed relative verb deficits. Table 2 shows the distribution of clinical diagnoses with respect to the direction of noun-verb naming differences. *****Table 2 is about here***** We decided to focus only on those cases in the literature where the difference was large in magnitude, i.e., a difference in accuracy of at least 30%. The rationale for removing cases with relatively small differences (even when these were significant) from further discussion was to allow us to focus on cases that are potentially theoretically significant. We relied here on Shallice (1988) who argued that it is important to be careful about which phenomenon is conceived as (double) dissociated. One of his criteria was that differences in performance levels between the dissociating categories need to be large. He distinguished between classical, strong 11 and trend dissociations and argued that inferences from trend dissociation “even if significant [...] are vulnerable, [...] inferences from classical dissociations and strong dissociations [...] are relatively untouched” (p. 244). The cut-off point of 30% is, admittedly, arbitrary, as any other cut-off point would have been, and has the risk of error on either side. The 30% threshold was a compromise figure arrived at by looking at the magnitude of differences found in the patients with relative verb and noun impairment listed in Table 1. Cases of relative noun deficits present with up to 80% difference, while the difference in the cases of relative verb deficits is smaller, the highest being 56%. We decided to use as threshold the closest round number to half of the average difference of noun and verb advantage together. Using this criterion, we removed from the analyses all cases with no noun-verb differences, 17 cases of noun impairment (55% of all such cases) and 160 cases of verb impairment (77% of all such cases). The larger proportion of verb impaired cases removed illustrates the point made earlier, that patients with relative noun deficits tend to present with larger differences between the categories than patients with relative verb deficits. In Table 3 the studies showing large differences between nouns and verbs are listed. There are 27 such studies reporting 63 patients with diagnostic category information. Lesion site information is given where available4. *****Table 3 is about here***** Among the 63 patients, 14 presented with relative noun deficits and 49 with relative verb deficits. The noun deficit group consisted of fluent type patients only. In contrast, the verb deficit group included Broca’s aphasic patients (29) as well as fluent (16) and mixed (4) patients. 12 Information about the lesion site is available for 36 patients, 12 with noun and 24 with verb deficits. In all the patients with noun deficits, damage to left temporal areas is reported. For three patients, the lesion is restricted to the left lateral temporal lobe, and for the remaining patients there was additional damage to left medial temporal, frontal, parietal and/or occipital lobes. For verb deficits, lesions range from damage to cortical areas including the frontal, temporal (medial and lateral), occipital and/or parietal lobe to the insula and/or subcortical structures (basal ganglia). The frontal (including Broca’s area and the prefrontal cortex), temporal, or parietal lobes in various combinations were implicated in the majority of cases. Table 4 gives lesion sites as described in the original papers (with variable detail and accuracy) for the patients with large noun-verb differences. *****Table 4 is about here***** In this sample of 36 patients with large noun-verb differences for whom lesion site information is available, damage limited to either frontal or parietal lobes or basal ganglia led to relative verb deficits, and damage limited to the temporal lobe led to relative noun deficits. In patients with mixed lesions with the involvement of anterior and posterior lesions, either noun or verb deficits were evident. Summary of the literature review Our survey of the literature showed that disproportionate verb deficits are more frequently reported than disproportionate noun deficits. This finding, along with other studies showing that the naming latencies of non-brain-damaged participants are slower in response to actions than objects (Bogka et al., 2003; Druks et al., 2006; 13 Szekely et al., 2005), as well as our study reported below, suggests that a large number of cases of verb deficits may be due to action naming being a more demanding task than object naming, rather than being due to true word class differences. For this reason, and following the cautious warning of Shallice (1988), we distinguished between relatively small (albeit often significant) and large nounverb differences. Our decision is based on the assumption that a large difference is unlikely to be caused solely by correlated factors, such as imageability differences between the words, and/or visual complexity differences between the pictures, or by verbs being generally more difficult than nouns6. We found that, although relative noun deficits are less frequent, when they occur, they tend to result in larger differences than relative verb deficits. In the smaller sample of cases with large differences, noun deficits were shown to be invariably associated with the clinical diagnosis of fluent aphasia. The relationship between clinical diagnosis and relative verb deficits, however, was less straightforward: while the majority of verb-impaired patients are Broca’s aphasics, there are 16 cases of fluent type patients with disproportionate verb deficits. Disproportionate noun deficits were found to be associated with temporal lobe damage, or more complex lesions involving, in addition to the temporal lobe, frontal, parietal and occipital lobes. Exclusive temporal lobe damage always resulted in a noun deficit, and in all reported cases of noun deficit, the temporal lobe was always implicated, highlighting the importance of temporal areas in the naming of concrete entities (e.g., Damasio et al., 2004). In contrast, disproportionate verb deficits are associated with a variety of lesion sites including the frontal and parietal areas and basal ganglia, and in some cases, also the temporal lobe. Different anterior lesions are associated with verb deficits but the involvement of the frontal lobe is not crucial for a 14 verb deficit to occur. The finding that heterogeneous lesion sites underlie disproportionate verb deficits may indicate that the functional basis for verb deficits is variable. In contrast, lesions that result in noun deficits are (somewhat) more homogeneous and, therefore, are possibly more specific, not only anatomically, but also functionally. This is, of course, extremely speculative, because the lesion information available in the studies reviewed is far from detailed enough, and our knowledge of mapping between anatomy and function is far from adequate. Nevertheless, the difference in the associated lesion sites undermines the view that noun and verb deficits are the mirror image of each other, i.e. that they occur because of impairments to the same processing component, which, we argue, is a precondition for the attested noun-verb differences to become theoretically informative. An object and action naming study In order to further explore noun-verb differences and the extent to which the greater processing demands of verbs may contribute to the dissociations, we carried out a new object and action naming study with aphasic patients and non-braindamaged comparison participants. Since the naming accuracy of non-brain-damaged participants is often at ceiling, the dependent variables were not only accuracy, but also latencies. We also provided an error analysis. No previous object and action naming study compared patients’ and controls performance on both accuracy and latency, and only very few previous studies with aphasic patients carried out a qualitative error analysis. Our study also used more and better matched object and action items with high levels of name agreement, and for each item in the test we had information about the length, frequency, familiarity, imageability of the word and 15 visual complexity of the picture. Since the noun and verb items in the battery could not be matched for these variables, they were used as predictors in regression analyses to explore their relative contribution to object and action naming. The patients were an unselected group of fluent and non-fluent type aphasic patients. The reason for working with patients of different diagnostic categories is that our focus of interest was object and action naming, and not diagnostic categories and the typical performance patterns they are associated with. In this study (i) we were interested in the patients’ level of performance in comparison to the control participants’; (ii) we wanted to see if the patients of different aphasia type would present with different patterns of performance, and (iii) we wanted to find out if the errors on object and action items would be of different kinds. Participants We included in the study patients in stable condition, with mild to moderate aphasia and without severe dysarthria. Nine aphasic patients, aged between 38 and 83, four males and five females participated. The aetiology in eight patients was cerebral vascular accident, and in one patient, brain tumour. Their levels of education ranged from nine to 16 years and they had normal or corrected-to-normal vision. Eight participants were monolingual English speakers and one was bilingual (BG). BG came to England from Poland at the age of ten and was educated in England to degree level and held a responsible managerial job that involved, among other things, giving speeches, until her stroke. She has now school age children with whom she speaks English exclusively. We are, therefore, satisfied that premorbidly her English was of high standard. No information about the lesion site of the patients was available. 16 Comparison data from non-brain-damaged participants was obtained from an on-going study conducted at the University of Essex (Druks et al., 2006) and for three younger participants from UCL. For the Essex study, participants were recruited through social clubs and doctor’s surgeries. I.Q. scores were obtained using Raven’s Coloured Progressive Matrices (Raven et al., 1992). Six comparison participants taken from the above sample, two male and four female, were matched with the patients in age and education level. The three London comparison participants were all female and had more years of education than the patients, though, both they and the patients with whom they were matched were educated to degree level. Demographic information about the patients and the comparison group is reported in Table 5. *****Table 5 is about here***** Background information about the patients’ speech and language behaviour Diagnostic classification was based on the analyses of the patients’ spontaneous speech. Two patients (LS and PM) present with typical Wernicke’s aphasia. Their speech is smooth, effortless and occasionally paragrammatic. Two patients’ language behaviour corresponds to that of Broca’s aphasia (AB and BG). BG is a high level Broca’s aphasic whose speech today is fluent and nearly effortless (though initially, according to the speech and language therapist’s report, was like that of a typical Broca’s aphasic), but still shows many agrammatic features such as verb, and free and bound grammatical morpheme omissions. AB, on the other hand, presents with effortful speech with phonological distortions, but no obvious agrammatism. 17 Three patients (BM, DOR and HC) present with mixed aphasic profiles, which are, in some but not in all respects, similar to that of Broca’s aphasia. All have reduced mean length of utterance and produce short, syntactically simplified, and often ungrammatical utterances. However, only HC has effortful speech, only BM and HC make phonological errors, and only DOR produced a reduced number of verbs in comparison to nouns. All three patients, in contrast to the pattern expected in Broca’s aphasia, produced an increased proportion of closed class words compared to open class words. One patient (CH) presents with anomic aphasia. CH is a high functioning anomic patient with appropriately fluent, syntactically complex and grammatical speech with word finding difficulties. Finally, SJ appears to be a transcortical motor aphasic, who produces very little, effortful, hesitant and non-fluent, but well articulated speech, using short incomplete phrases. Her comprehension, writing of single words and repetition is very good. Table 6 summarizes the speech characteristics of the patients, including words per minute produced, mean length of utterance (MLU), the number of words produced in their longest utterance (LU), the proportion of verbs in comparison to nouns, and the proportion of closed class words in comparison to open class words produced in spontaneous speech. The speech analysis was carried out following the procedure suggested by Berndt, Wayland et al. (2000) and it contributed to the clinical diagnosis ascribed to the patients. *****Table 6 is about here***** Materials The stimuli used consisted of line drawings of 100 objects and 100 actions (Druks and Masterson, 2000). All stimuli obtained high levels of name agreement (at 18 least 93%), and the noun and verb items are matched pair-wise for rated age of acquisition. The reason for using age of acquisition as the matching criteria is that, according to current evidence, this variable has the strongest effect on word retrieval (e.g., Morrison et al., 1992). In addition to information about age of acquisition of items in the battery, information about frequency (Francis and Kucera, 1982), rated familiarity and imageability, syllable length of the verbal labels and rated visual complexity of the pictures is also available. These are summarized in Table 7. The noun and verb items in the battery were very closely matched for age of acquisition. In order to find out whether the two sets differed on the other variables, ttests were carried out. The nouns and verbs in the battery do not differ in terms of familiarity [t(198)=1.71, p=.09], the verbs are of marginally higher frequency than the nouns [t(198)=1.94, p=.054]. However, the verbs are rated lower in imageability [t(198)=8.36, p<.001], and are longer than the nouns [t(198)=8.36, p<.001]. In addition, the action pictures are visually more complex than the object pictures [t(198)=5.01, p<.001]. The pictures were presented using Powerpoint on the screen of a Macintosh Powerbook computer, and responses were recorded continuously with Soundedit audio recording software (version 2.0.7, Felt Tip Software, Kwok, 2002). Latencies were calculated from the spectrogram from the time the picture appeared on the screen until the onset of the correct target response. Use of Soundedit allows for the recording of precise latencies for correct responses, even when the participant produces preresponse vocalisations (e.g., um, er, the, this is) and other false starts, including selfcorrected incorrect responses. This method is preferable, therefore, to the use of a voice activated relay, commonly used to collect naming latencies, which can involve 19 the loss of a substantial number of data points due to premature voicekey activation caused by pre-response verbalisations and false starts. ****Table 7 is about here ***** Procedure Participants were asked to name aloud 100 object and 100 action pictures as quickly as possible using a single word. The practice trials comprised twelve action pictures and twelve object pictures not included among the experimental items. During the practice trials, patients were trained to name the objects with a single noun and the actions with a single verb in the –ing form which is known, from past experience, to be the most frequent response in action picture naming. The test was presented in blocks of 25 object and 25 action pictures, alternating. Half of the participants started with a block containing object pictures, and the other half, with a block containing action pictures. Items within the blocks were presented in a predetermined random order. Each block began with a screen with the block number, and participants were informed about the picture type they would see. The presentation began with a button press by the experimenter who also controlled the presentation of the pictures by button press. The experimenter moved on to the next trial when the participant either gave a response or after a ‘suitable’ period of time (approximately 30 seconds) had elapsed. Participants were offered a rest period between blocks. Results 20 Target responses, and multiword responses that contained the target (e.g., shooting → there is shooting the birds; building → trying to build something out there; pocket → hand in his pocket) entered the latency analysis. Acceptable synonyms (e.g., axe → a chopper, 18.31% of the data), were counted as correct for the accuracy analyses, but were discarded from the latency analysis. An additional 0.19% of the data was discarded due to technical problems. Finally, very slow responses, i.e., latencies extending two standard deviations above each participant’s own mean latency, were also excluded (2.25% for nouns and 2% for verbs). Overall, 22.75% of the naming latencies were removed from the analysis. Mean naming latencies of the patients and of the comparison group in response to the object and action pictures are reported in Table 8. *****Table 8 is about here***** Naming latencies We carried out a 2×2 split plot ANOVA on the latencies of the patients and the comparison group. The effect of group was significant, F(1,16) = 6.58, p =.02, with latencies of the patients slower than those of the comparison participants. The effect of picture type was also significant, F(1,16) = 10.69, p =.005, with latencies for action naming slower than for object naming. The interaction was also significant, F(1,16)=9.18, p=.008. In order to explore the interaction, we carried out four t-tests. The comparison of object and action naming latencies in the patients [t(8) = 2.951] and in the comparison group [t(8) = 2.374] was not significant7. We also compared object naming latencies [(t(16)=2.943, p=0.01)] and action naming latencies [(t(16)=3.002, p=.008)] between the patients and the comparison participants This 21 showed that the effect of group was more pronounced for action naming than object naming. Individual patients and comparison participants We compared the naming latencies in response to object and action pictures of individual patients and comparison participants using Mann Whitney tests. Action naming was significantly slower than object naming for six patients – AB [z=-5.282, p< .001], BG [z=-6.584., p<.001], BM [z=3.896, p<.001] HC [z=-4.568, p<.001], PM [z=-3.362, p=.001] and SJ [z=-4.062, p<.001]. For eight comparison participants action naming was somewhat slower than object naming, and for one, the difference was in the opposite direction. These differences, however, were not significant. Summary and discussion of latencies The patients’ naming latencies were longer than those of the comparison group. Both the patients and the comparison group were faster in naming objects than actions. This also holds true for the majority of individual patients, and the difference was significant for six. While none of the previous object and action naming studies of aphasic patients collected naming latencies, longer latencies for action than object pictures were consistently found in the few studies that compared latencies in object and action naming in non-brain-damaged individuals (Székely et al., 2005 with normal English speakers; Bogka et al., 2003 with English and Greek speaking adults; Druks et al., 2006, with older adults) and in Alzheimer’s disease (Druks et al., 2006). The consistent performance pattern of the comparison participants in the different studies suggest that action naming is more demanding than object naming. This additional complexity of action naming evident in non-brain-damaged populations 22 may contribute to the frequently found verb deficits in aphasia. This would mean that some attested verb deficits are due to action naming being generally more difficult, instead of being the impaired half of the double dissociation. Errors Table 9 presents the number of errors made in response to object and action pictures by individual patients and the comparison group. We carried out a 2×2 split plot ANOVA on the number of errors made by the patients and the comparison participants. There was a significant effect of group, F(1,16)=12.56, p=.003, showing that patients made more errors. The effect of picture type was also significant, F(1,16) = 21.14, p < .001, with action pictures eliciting more errors than object pictures. The interaction was also significant, F(1,16) = 8.90, p = .009. In order to explore the interaction, we carried out four t-tests. We compared accuracy of naming objects and actions in the comparison group [t(8)=-2.287, n.s.] and in the patients [t(8) = 4.051, p = .004]. This shows that the effect of picture type is more pronounced in the patients than in the comparison group. When we compared accuracy of object naming in the two groups, we found that the difference was not significant [t(16)=1.93]. For actions, the difference was significant [t(16)=3.85, p=.001]. This showed that the effect of group was important for accuracy in action naming but not in object naming: patients made significantly more errors in naming actions, but not in naming objects, than the controls. ****Table 9 is about here**** Individual patients 23 All patients made more errors in action than object naming, and for five patients, using Fisher Exact test, the difference was significant [BM, p=.029; HC, p=.031; CH p=.048; PM p<.001; SJ, p<.001]. Qualitative analysis of errors Overall, 78 errors were made in naming objects and 197 in naming actions by the patients. Table 10 reports the error classification system used with examples, and the number and percentage of errors classified according to type. The errors were classified according to error type by two of the authors (SM and JD), using a pre-specified classification system. In assessing the errors and their classification, it is important to take into consideration that all the pictures in the battery obtained high levels of name agreement by non-brain-damaged informants, and that, in classifying the errors, we considered the response not only in relation to the target word, but also in relation to the properties of the pictures. We did so in order to understand the reason for making a specific error. This turned out to be particularly decisive for some visual type errors that would have remained incomprehensible without looking at the picture that elicited them. We distinguished between semantic, visual, and ‘other’ errors. Among the semantic errors we included co-ordinate (that can be indistinguishable from visual errors, since some co-ordinates are visually similar to each other) super-ordinate, subordinate, and associative errors. Among the visual errors we included frank visual errors and ‘misinterpretation of the picture’ errors. We classified as ‘misinterpretation of the picture’, (i) responses that named an unintended part of the picture that was present in the picture (e.g., cooking → chef); (ii) responses that appeared as if the inferences necessary to get to the intention of the picture had not been made (e.g., 24 waiter → man carrying a tray); and (iii) responses that remained too closely attached to the visual appearance of the picture, lacking in semantic interpretation (e.g., button → round circle with four dots). These errors constitute the most prominent indication of the complexities involved in picture naming in general. ‘Misinterpretation of the picture’ errors are also the most likely candidate for errors caused by executive control failures. They affected both object and action naming, though to a larger extent, action naming, possibly, due to action pictures being both visually and conceptually more complex than object pictures. ‘Misinterpretation of the picture’ errors may occur because of genuine misinterpretation, especially in the case of patients with semantic deficits. However, in the case of aphasic patients with word finding difficulties, we cannot be sure of their underlying source. These errors often involved naming an object that was present in an action picture, or producing a verb in response to an object picture. The former type of error occurred especially frequently, and since they could be the result of verb deficits rather then misinterpretation, we counted them separately in Table 10. Among ‘other’ errors we included phonological distortions, omissions and circumlocutions. Circumlocutions were adequate definitions of the target, occurring most likely because of lexical retrieval problems. *****Table 10 is about here***** Summary and discussion of errors The patients made more errors than the comparison group, and actions elicited more errors than objects in both the comparison and patient group, though the difference did not reach significance in the comparison group, possibly, because of 25 the small number of errors this group made. Case by case analysis revealed that all patients made more errors in action naming, and the difference was significant for five. For two patients, SJ a transcortical motor aphasic patient, and PM a Wernicke’s aphasic patient, the difference was especially large. The patients’ performance in the present study is similar to that in other studies that also report a disproportionate number of errors in response to action pictures (e.g., Berndt et al., 1997b; De Bleser and Kauschke, 2003; Jonkers and Bastiaanse, 1998). Overall, object pictures were more susceptible to semantic type errors than action pictures. Action pictures, on the other hand, elicited many ‘misinterpretation of the picture’ errors (including naming objects present in an action picture and other misinterpretation errors) circumlocutions and omissions. In both categories there were only few frank visual errors, and few super-ordinate and sub-ordinate errors. The finding, that noun targets were most frequently substituted by semantically related items (in particular co-ordinate errors) is compatible with the suggestion that nouns are represented in a hierarchically organized system in which entities within a semantic category share many features (Huttenlocher and Lui, 1979; McRae et al., 1997). Such a semantic organisation is likely to induce such errors. Action pictures, on the other hand were susceptible to more complex error types than object pictures: ‘misinterpretation of the picture’ errors (not only noun-errors in response to action pictures, but other misinterpretation errors) and circumlocutions. Both error types occur, possibly, due to action pictures having a less direct relationship to their verbal label (than object pictures) requiring more inference making, and/or verbal descriptions. Interestingly, control participants for our study with AD patients (Druks et al., 2006; Masterson et al., 2007) who made few errors overall (an average of 1.00 or less in each category), made most errors in the ‘misinterpretation of picture’ 26 category (an average of 1.73 on objects, and almost 2.90 on action pictures). Thus these errors are also prominent in non-brain-damaged participants in timed naming, showing, possibly, that they are an inherent component of picture naming. In general, the identification of the source of the errors in picture naming is only straightforward in the case of phonological or frank visual errors. All other errors may occur either because of semantic feature loss (or inadequate access to semantic features), loss of a lexical form (or an inability to access a lexical form), or, even, due to less efficient executive control functions such as attending to the picture, focusing on the right part of the picture, making a decision about the required response and inhibiting a possible (i.e., naming an object in an action picture) but inappropriate response. Unless there are strong indications for semantic loss or preservation, and/or other independent evidence, it is difficult to distinguish reliably among these possibilities. Regression analyses: latency data of control participants Error trials were removed, and the data were trimmed by excluding latencies longer than 3 seconds (in 29 trials out of 1800). The remaining trials were averaged across subjects. Independent-samples t-test between items revealed that verbs were significantly slower than nouns (1.229 vs. 1.068 respectively; [t(198) = 5.133, p < .001]). Other psycholinguistic variables, however, may have contributed to this difference. In order to explore this, a sequential linear regression was carried out using latencies as the dependent measure. A first step partialed out the variance due to frequency, age of acquisition, imageability, visual complexity and familiarity. The residuals from this model were passed on to a second step where word class was used as a predictor. 27 In the first step, significant predictors were age of acquisition (standardized beta = .190, t = 2.593, p=.01), imageability (standardized beta = -.496, t = -7.182, p< .001), and visual complexity (standardized beta = .187, t = 2.898, p = .004). Frequency and familiarity were not significant predictors (p>.75). Adjusted R2 for this step was .285. In the second step, word class was not a significant predictor (standardized beta = .042, t=.311, p > .75; partial correlation = .022, n.s.). Logistic regression analyses: accuracy data of individual patients Since the patients differed from each other on a number of potentially important variables such as diagnostic category, severity of aphasia, naming ability, the magnitude of difference between object and action naming and accuracy, we envisaged that different psycholinguistic factors might have an effect on their naming. Therefore, we carried out logistic regression analyses on the accuracy data for each patient. We entered phoneme length, age of acquisition, imageablity and grammatical class as predictor variables. For AB, BG, BM, HC, and PM none of the predictors were significant. Imageability was associated with accuracy for SJ (b = -1.44, Wald χ2 = 10.13, df=1, p = .001), CH (b = -.846, Wald χ2 = 4.77, df=1, p = .029) and DOR (b = -1.33, Wald χ2 = 14.41, df=1, p = .000), and age of aquisition (b = 1.09, Wald χ2 = 5.57 df=1 p = .018), for LS. Summary and discussion of regression analyses The analyses conducted on the control participants’ latencies showed that imageability was the most potent predictor, together with age of acquisition and visual complexity, while frequency and familiarity were not significant predictors. In the second step, grammatical class was shown not to be a significant predictor. In the 28 analyses of the accuracy of individual patients using regression, different variables predicted the performance of different patients. For three patients, imageability was a predictor, for one patient, age of acquisition, and for five patients, none of the variables that entered the analysis turned out to be predictors. The regression analyses show that rated imageability of words is an important determiner whether or not a word will be produced. It accounts for a considerable proportion of the variance to the extent that when imageability (together with other predictors) is taken into consideration, grammatical is not significant. However, we need to remember that (rated) imageability, and in particular, the imageability of verbs, is a little understood construct (see Bogka et al., 2003 for a discussion). Admittedly, there is much accumulated data for imageability ratings for (mainly concrete) nouns (though little for verbs). Despite this, we do not yet understand the principles according to which participants carry out the imageability rating task. Moreover, imageability rating of nouns and verbs might be an entirely dissimilar process, in which case the ratings may not be validly comparable. One serious problem is that the instructions traditionally given for imageability ratings for nouns and verbs are identical and emphasize the importance of sensory features (and not of motor features), despite the intuition that what makes nouns and verbs imageable may be different. For this reason, we believe that the imageability ratings of verbs currently available, including our own for the Object and Action Naming Battery, are suspect. Additional evidence for the problems related to the imageability ratings of verbs, comes from Chiarello et al. (1999) who measured the time it took for participants to provide imageability ratings for nouns and verbs and found that, in general, fastest imageability ratings were given to words rated most highly imageable. However, this association was stronger for nouns than for verbs, and the relationship 29 between imageability ratings and response times for verbs was less consistent then for nouns. All this seems to suggest that the underlying processes of imageability ratings for nouns and verbs are different. Having said this, if we accept the concept of imageability as it is understood today by most researchers, it is admittedly the most potent variable to account for differences between object and action naming in non-brain-damaged control participants, supporting, at least to some extent, the view of Bird et al. (2000) who argued that noun verb differences in aphasic patients are reducible to imageability differences between nouns and verbs. Bird et al.’s position implies that patients with relative verb deficits will always perform better on all highly imageable words, and patients with relative noun deficits, will perform better on abstract words. These claims have not yet been extensively researched. One exception is a study of Berndt et al. (2002), who found that five patients with relative verb impairment in picture naming were also disproportionately impaired in producing verbs in sentence completion in which the last word, either an (abstract) noun or an (abstract) verb was missing. This showed that verb deficits are also evident in a task that uses only abstract nouns and verbs with similar imageability levels. A problem with this study as previously noted, however, is that no patients with relative noun deficits in object naming were tested to see if they would present with the reverse pattern. Marshall et al. (1995/6), in a single case study, showed that, for their patient, there was a relationship between noun deficits and imageability effects. They described a patient who uses more readily abstract than concrete words in connected speech and is better at verb than noun production. In relation to verbs, the patient performed better on tasks that required accessing their argument structure (a more 30 abstract feature of verbs) than their perceptual features. This showed that for this patient there was a link between noun deficits and reversed imageability effects. However, this link is not often reported, and, therefore, we do not know if it generalizes to other patients with relative noun deficits. Discussion of the object and action naming study There were three findings in this study. First, both patients and the comparison group were slower and made more errors in naming action pictures than object pictures. Second, action naming was more impaired than object naming not only in Broca’s aphasic patients but also in patients with anomia and Wernicke’s aphasia. Third, objects elicited different types of errors than actions: object pictures elicited mainly semantic errors, while action pictures elicited mainly errors involving circumlocutions and ‘misinterpretation of the picture’ errors. The present study, however, could not provide information about the relationship between noun or verb deficits and lesion site, because no lesion site information was available. The finding that the comparison participants’ performance was in the same direction as the patients’ confirms that action naming is more difficult than object naming, possibly, due to the lower imageability of the former, or other factors such the higher interpretative demand of action pictures, or factors not yet identified. The finding that fluent type patients also present with verb deficits weakens the traditionally held view that verb deficits are associated with Broca’s aphasia and anterior lesions, and converges with results from other group studies (e.g., De Bleser and Kauschke, 2003; Luzzati et al., 2002). The finding that different error types were made on the two picture types indicates that they pose different demands for the language system. 31 General discussion In the introduction we outlined a number of reasons why action naming (and verb production) might be more difficult than object naming (and noun production). Among these reasons we listed the following: verbs have a more complex semantic organization than nouns; verbs have a pivotal role in sentences; verbs attract more potential functional markers than nouns; and verbs are lower in imageability than nouns. We argued earlier that any of these reasons in isolation or in combination with others may account for disproportionate verb deficits. However, despite the reasons for expecting verbs to be more susceptible to impairment than nouns, there are also patients who are more impaired with nouns than verbs. These two types of impairment constitute a double dissociation. In this paper we closely examined the nature of noun-verb differences evident in the literature. It is widely accepted that picture naming may fail for a variety of reasons such as visual problems, semantic deficits or grammatical deficits, loss of word forms, or impaired access to word forms. For this reason the interpretation of the double dissociation between nouns and verbs is not straightforward. If, for example, noun deficits occur due to loss of conceptual-semantic features and verb deficits, due to grammatical deficits related to argument structure, than no theoretical insights may legitimately be derived from the evident double dissociation. If, however, both noun and verb deficits occur due to conceptual-semantic impairments (degraded perceptual features for nouns and degraded motor features for verbs, for example), or if the contrast is of grammatical class, then the dissociations would be theoretically informative. The present study provided evidence suggesting that a subset of cases of 32 selective verb deficits may be due to verbs posing more processing demands than nouns. First, all nine patients irrespective of their clinical diagnosis were faster and more accurate in naming object than action pictures. Second, comparison participants performed similarly both in terms of latencies and accuracy (though only the latency difference was significant, accuracy was not, possibly because of the small number of errors made). These results are in line with previous studies using the same (Bogka et al., 2003; Druks et al., 2006) and other materials (Szekely et al., 2005). Third, the literature review revealed that there are far more reported cases of verb than noun impairments (209 vs. 31). Fourth, there are differences between the levels of preservation of the less affected category. Among the 31 patients with large verb deficits that we reviewed, 12 presented with noun scores of at least 90% correct and another 18 with scores of 80% or higher. In contrast, the 11 patients with large noun deficits performed considerably less well on verbs, with scores ranging between 59% and 88%, with the majority of patients producing around 70% correct verb responses (see Table 3). This shows that object naming may remain relatively well preserved in the face of very impaired action naming, but when object naming is very impaired, action naming (while relatively better preserved) is also impaired. On the basis of this evidence from our own and of others’ work, both with patients and with non-braindamaged individuals, therefore, it must be concluded that the noun- verb dissociation is not balanced, which, partially, is due to action naming being more demanding than object naming. In order to distinguish between cases of true noun-verb difference that are theoretically relevant, and cases in which noun-verb differences are due to additional processing demands of verb production, as a first step, only cases that present with large differences between the two categories should be considered. This is why we 33 distinguished between studies that reported smaller and larger noun-verb differences. In the following, concentrating only on cases with large differences between nouns and verbs (14 patients with noun deficits and 49 with verb deficits), the relationship of the deficit to diagnostic category and lesion site (where such information was available) is discussed. The patients with disproportionate noun deficits were all diagnosed with anomic aphasia and presented with fluent and grammatical speech with word finding difficulties (with the exception of one patient who was described as producing jargon). There is more variability in the verb impaired group. Although the majority (29) of the 49 patients with large verb deficits were classified as either ‘agrammatic’, ‘Broca’s aphasic’ or ‘non-fluent’, there were also 16 patients classified as fluent and four with a mixed diagnosis. This shows that while the association between diagnostic category and noun deficits appears to be reliable, it is not so between diagnostic category and verb deficits, even when only cases with large differences are considered. Despite the similar clinical features of the noun impaired patients – anomic speech and selective object naming deficits – the locus of lesion for these patients was variable, and in the case of four patients, the lesions were surprisingly widespread. However, what unifies all patients with noun deficits is that all had a lesion in the temporal lobe. The brain regions affected in patients with relative verb deficits are more wide ranging: frontal, temporal, parietal and occipital lobes were implicated in different constellations in different patients (in addition to deep frontal structures such as the basal ganglia and the insula). In contrast to the invariable involvement of the temporal lobe in the noun impaired group, frontal lobe lesions were not reported in all cases of verb deficits (there are nine such cases with parietal, occipito-parietal and 34 temporo-parietal lesions), and lesions in Broca’s area are reported only in two out of the 24 cases. In fact, frontal, temporal and parietal lesions were involved with similar frequency. The 16 fluent type patients (and the mixed patient) with relative verb impairments differed in their lesion from the non-fluent type patients who were similarly impaired in verb production. For example, JH (Berndt and Haendiges, 2000) had a left basal ganglia lesion, HW (Caramazza and Hillis, 1991), a left occipito-parietal lesion, TB (Jonkers and Bastiaanse, 1998), a lesion involving the internal capsule and white matter, HG (Shapiro and Caramazza, 2003b) had left frontotemporal and basal ganglia lesion, and SM (Silveri and Di Betta, 1997), who presented with mixed aphasia, had a lesion in the white matter around the parietal lobe, external capsule and the thalamus. In addition to the patients in the literature review, PM a typical Wernicke’s aphasic in the study reported here also showed a large relative verb deficit. In contrast to these varied lesion sites of fluent patients with verb deficits, the majority of the non-fluent type patients with a verb deficit had more straightforward frontal lobe involvement. This contrast between the two groups of verb impaired patients seems to suggest that in-depth comparisons between non-fluent and fluent patients exploring both their lesions and language differences may yield insight into the different forms verb deficits may take. Alongside the exceptions and the unexplained cases, there is also a remarkable systemacity in so far that, by and large, fluent type patients tend to present with noun deficits and non-fluent type patients with verb deficits. Similarly, the association of verb deficits with anterior damage (frontal and parietal lobe and basal ganglia), and the association of noun deficits with temporal (lateral and medial) and temporooccipital damage was also upheld in the majority of cases. However, closer 35 inspection suggests that both these generalisations hold only when the lesions are not complex, i.e., they do not involve both typical anterior and posterior regions. We counted 12 cases of patients with lesions involving both the frontal and temporal lobes (L. fronto-temporal, fronto-temporo-parietal and R. fronto-temporal). Three had relative noun deficits, EBA (Hillis and Caramazza, 1995), Mario (De Renzi and Di Pellegrino, 1995) and SK (Berndt et al., 1997a), and nine had relative verb deficits, RC (Shapiro and Caramazza, 2003a), AM and CS (Miceli et al., 1988), HG (Shapiro and Caramazza, 2003b), LK (Breedin and Martin, 1996) and LN (Breedin et al., 1998). This shows that very similar gross lesions may result in either noun or verb deficits. Moreover, some of these patients were described as Broca’s aphasic/agrammatic/non-fluent (RC, AM, CS, LK, LN, FC, LZ, MB) and some as anomic/fluent (EBA, Mario, SK and HG8). It appears that complex and widespread lesions may have unpredictable consequences: sometimes they result in fluent and sometimes in non-fluent aphasia; sometimes they result in noun deficits and sometimes in verb deficits. We have argued elsewhere (Druks and Carroll, 2005) that we still do not understand the consequences of mixed lesions, though mixed lesions are not an infrequent occurrence. Their effect does not seem to be additive (at least, not always). Large mixed lesions often do not result in global aphasia, as demonstrated by the cases of Mario, EBA and SK who, despite huge lesions, were anomic and without signs of anterior aphasia type productive language (and they had selectively preserved verb production). This puzzling phenomenon cannot be resolved at this stage and it poses difficult questions for attempts to neatly localize noun or verb deficits, and to the double dissociation view of noun-verb differences. Finally, we return to the issue of double dissociation between noun and verb 36 deficits in aphasia. There are two observations to make. First, on the strength of the evidence it seems that the scope of the double dissociation is reduced because there are numerous reports of patients with relatively small (albeit significant) verb deficits in the literature that are likely to be due to the heavier processing demands of verbs. These cases do not, therefore, constitute a part in the double dissociation relations. Second, there are indications that noun and verb deficits may often occur for different underlying reasons in which case the evidence of a double dissociation has no theoretical implications for the functional and anatomical organization of nouns and verbs. Lesion sites and language impairments additional to the noun or verb deficits may help to identify the underlying reason for either noun or verb deficits. Our literature review, for example, showed that the involvement of the temporal lobe is crucial for noun deficits to occur, while the frontal lobe is not always implicated in the verb impaired group, and lesion sites in this group are generally more variable. On the basis of this information, perhaps we are allowed to speculate that object naming is (often) impaired due to loss of object knowledge and/or loss of sensory features, which are known to be dependent on temporal lobe structures, and that the variable lesion sites underlying verb deficits imply that there may be a variety of reasons for verb deficits. This, however, at this stage must remain speculation because our knowledge of mapping between function and anatomy is still too sketchy. The presence of additional language (or other) deficits may facilitate the disambiguation of the underlying reasons for action naming deficits in future studies It is important to know, for example, whether or not a patient with action picture naming deficits also presents with lack of verbs in connected speech. There is some evidence that the two do not necessarily go together. Druks and Carroll (2005) report 37 a patient with very few verbs in connected speech, but whose action picture naming is only moderately impaired. In the present study, there was also no direct one-to-one correspondence between action picture naming ability and verb production in connected speech. Action picture naming deficits without parallel verb deficits in connected speech may imply that the deficit is conceptual-semantic or lexical, rather than grammatical. Differences in the availability of lexical verbs and auxiliaries may also provide a useful diagnostic. Patients who replace lexical verbs with auxiliaries are unlikely to omit verbs because of grammatical problems (see Druks and Carroll, 2005). Finally, comparison between the availability of abstract and concrete nouns and verbs may allow for the differentiation of conceptual-semantic and grammatical class sources of noun-verb differences The case of LEW (Druks and Shallice, 2000), and of TP (Yoon, Humphreys and Riddoch, 2005) are good examples that demonstrate the involvement of action programmes and/or action semantics in verb production. Both patients presented with modality specific naming deficits but the pattern of deficit in the two cases was somewhat different. LEW had severe anomia in the visual modality that included the naming of action pictures. However, he was able to name actions that were acted out for him, his own actions and actions that were carried out on his body. His object naming deficit, on the other hand, remained profound in all forms of task presentation in the visual modality. He had excellent access to semantics of both objects and actions and nouns and verbs. Druks and Shallice interpreted LEW’s spared action naming as being due to preserved links between unimpaired action semantics and the output lexicon (while links between visual semantics and the output lexicon were dysfunctional). A somewhat similar patient is TP who presented with relatively well preserved verb production in picture naming, but not in reading. Since he could not 38 read non-words, it was concluded that his reading relied on semantics which was also impaired especially for (action) verbs and evident also in spoken word-picture matching. Yoon et al. (see also Yoon, Heinke and Humphreys, 2002) argued that the relatively well preserved action naming of TP, despite impaired semantics, shows that unimpaired access to action programmes through direct visual route to action that bypasses semantics may support not only actions but also action naming (by interacting with the naming route). The cases of LEW and TP demonstrate the involvement of action programs (either supported by semantics, or direct) in action naming. This is a plausible account for at least some patients’ spared action naming (possibly those patients who show a very large verb advantage). If true, the selective verb advantage of these patients should disappear when abstract nouns and verbs are probed. While the intactness of action programs may be essential for action naming, their impairment is not the only possible reason for verb deficits. The cases of RC (Shapiro and Caramazza, 2003a) and JR (Shapiro et al., 2000) exemplify a form of noun-verb double dissociation, manifested not only in picture naming and word repetition (including abstract words) but also in a sentence completion task in which the noun and verb forms of a homophonic word (and pseudo-words) had to be inflected for the plural and third person singular respectively. JR was more impaired in producing nouns and RC in producing verbs. Here the double dissociation is argued to be at the level of the lexicon and morphology that is associated with grammatical class. The patients LEW, TP, RC and JR and others show that noun and verb deficits may occur for different reasons and therefore, in order to use the evidence of double dissociation to learn about functional and neuroanatomical organisation, it is essential 39 to show that the impairments to the two categories are comparable – conceptual, or semantic, pertaining to grammatical class or morphological. The results for the patients reported in this study, and other relevant cases, as well as the variable diagnostic categories and the lesion sites implicated in the noun and verb impaired patients indicate that previous claims in relation to the implications of noun-verb double dissociation in the literature have often been made without strong enough and/or appropriate evidence. 40 Footnotes 1 When adequate matching of items in a study is considered one must remember that it is almost impossible to match the noun and verb items on more than one or, at most, on two variables. The reason is that matching on one variable results in the materials becoming unmatched on other variables that might also be influential in word retrieval. 2 In the reviewed papers a variety of diagnostic terms were used to label possibly similar or not well distinguished clinical presentations (e.g., Broca’s aphasia, non-fluent aphasia and agrammatic aphasia). In the review throughout, we used Broca’s aphasia, instead. Instead of Wernicke’s aphasia, anomia and fluent aphasia, we used fluent aphasia, mainly because we did not know if the label ‘fluent aphasia’ used in past papers referred to Wernicke’s aphasia or anomia. Nevertheless, the distinction between Wernicke’s aphasia and anomia was maintained where it was important. Mixed aphasia was used whenever it was clear from the paper that the patient could not be classified as Broca’s aphasic or fluent aphasic. 3 Luzzatti et al. (2002) report results for 51 patients. This is reported here as group data. Results for individual patients with large (30%+) differences are reported in Table 3. 4 Among the cases that were removed from further analysis there were also three fluent patients with large (but smaller than 30%) relative verb advantage (Miozzo et al., 1994; Rapp and Caramazza, 2002; Shapiro et al., 2000) and eight Broca’s aphasics and 11 fluent patients with large (but smaller than 30%) relative verb impairment (Berndt et al., 1997b; Bird et al., 2000; De Bleser and Kauschke, 2003; Jonkers and Bastiaanse, 1996; Zingeser and Berndt, 1998). These cases would have entered the analysis if the decision to use a lower cut-off criterion had been made. 5 Test results are from Luzzatti et al., 2002. Patients’ initials and lesion sites are from Aggujaro et al., 2006. When no initials were available, patients’ numbers were taken from Luzzatti et al., 2002 (for these patients no lesions sites are available). 6 It has been pointed out to us that since action naming is known to be more difficult than object naming, in order to demonstrate theoretically interesting differences, we should put the cut-off point higher for verb impaired cases than noun impaired cases. This is a valid comment and we should do so in an ideal world. However, the methodology used in collecting the data that we are considering here is not always reliably comparable. Especially in the earlier studies, noun and verb items were not adequately matched, and name agreement levels were often low. These factors cannot be controlled for 41 today, and this is the main reason for us to set up a relatively conservative cut-off point for cases to be considered as true noun-verb dissociations. 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Brain and Language, 39: 14-32, 1990. 50 Table 1: Summary information for the 38 studies reporting object and action picture naming data Study and patients Numbers correct naming objects Numbers correct naming actions Magnitude % of verb advantage Magnitude% of noun advantage Basso et al., 1990 29 fluent patients 15/20 (75%) 14/20 (69%) 6 30 Broca’s patients 12/20 (61%) 12/20 (61%) 43/60 (72%) 29/60 (48%) 29/60 (48%) 29/60 (48%) 55/60 (92%) 46/60 (77%) 15 47/60 (78%) 35/60 (58%) 20 40/60 (67%) 18/60 (30%) 37 49/60 (82%) 29/60 (48%) 34 30/60 (50%) 17/60 (28%) 22 44/60 (73%) 31/60 (52%) 21 43/60 (72%) 35/60 (58%) 14 54/60 (90%) 46/60 (77%) 13 51/60 (85%) 38/60 (63%) 22 50/60 (83%) 19/60 (32%) 51 26/60 (43%) 12/60 (20%) 23 48/60 (80%) 24/60 (40%) 40 43/60 (72%) 34/60 (57%) 15 43/60 (72%) 45/60 (75%) 42/48 (88%) 12/37 (32%) 56 34/48 (70%) 23/37 (61%) 9 40/48 (83%) 27/37 (73%) 10 40/48 (83%) 16/37(43%) 40 21/48 (44%) 13/37 (35%) 9 25/48 (53%) 14/37 (38%) 15 0 0 Bastiaanse and Jonkers, 1998 8 Broca’s patients 8 fluent patients 24 0 0 3 Bates et al., 1991 6 Broca’s patients 51 Table 1 to be continued Study and patients Numbers correct naming objects Numbers correct naming actions Magnitude % of verb advantage Magnitude% of noun advantage Bates et al., 1991 7 fluent patients 23/48 (48%) 20/37 (54%) 6 1/48 (2%) 7/37 (19%) 17 6/48 (13%) 9/37 (24%) 11 22/48 (46%) 22/37 (59%) 13 9/48 (19%) 6/37 (16%) 3 23/48 (47%) 16/37 (42%) 5 5/48 (10%) 7/37 (19%) 25/27 (93%) 25/27 (91%) 2 24/27 (87%) 22/27 (81%) 6 22/27 (83%) 19/27 (70%) 13 26.5/27 (98%) 24/27 (87%) 11 25/27 (91%) 25/27 (91%) 12/27 (44%) 6/27 (22%) 22 24/27(89%) 15/27 (56%) 33 22/27 (83%) 10/27 (35%) 48 19/27 (70%) 10/27 (37%) 33 15/27 (57%) 11/27 (41%) 16 9 Berndt et al., 2002 5 fluent patients 4 Broca’s patients 1 mixed patient 0 0 Berndt et al., 1997a 1 fluent patient 14/30 (47%) 23/30 (77%) 24/30 (80%) 14/30 (47%) 30 Berndt and Haendiges, 2000 1 fluent patient 33 52 Table 1 to be continued Study and patients Magnitude % of verb advantage Magnitude% of noun advantage Numbers correct naming objects Numbers correct naming actions 55/60 (91%) 21/30 (70%) 21 55/60 (92%) 12/30 (40%) 52 24/60 (40%) 5/30 (18%) 22 43/60 (71%) 19/30 (63%) 8 59/60 (99%) 29/30 (99%) 53/60 (88%) 19/30 (63%) 25 47/60 (79%) 16/30 (54%) 25 44/60 (73%) 21/30 (71%) 2 60/60 (100%) 29/30 (95%) 5 29/60 (49%) 25/30 (83%) 34 27/60 (45%) 21/30 (69%) 24 Berndt et al., 1997b 5 Broca’s patients 6 fluent patients 0 0 Bi et al., 2005 1 fluent patient 26/64 (41%) 50/64 (78%) 37 Bird, et al., 2000 3 Broca’s patients 3 fluent patients 83/114 (73%) 33/84 (37%) 36 106/114 (93%) 63/84 (76%) 17 91/114 (80%) 45/84 (52%) 28 107/114 (94%) 73/84 (88%) 6 81/114 (71%) 76/84 (90%) 19 92/114 (81%) 70/84 (81%) 0 0 Breedin and Martin, 1996 3 Broca’s patients 1 fluent patient 56/60 (93% ) 19/30 (63% ) 30 31/60 (52% ) 10/30 (33% ) 19 49/60 (82%) 22/30 (73%) 9 24/60 (40%) 5/30 (17 %) 23 53 Table 1 to be continued Study and patients Numbers correct naming objects Numbers correct naming actions Magnitude % of verb advantage Magnitude% of noun advantage Breedin et al., 1998 8 Broca’s patients 34/60 (57%) 13/30 (43%) 14 53/60 (88%) 25/30 (83%) 5 55/60 (92%) 22/30 (73%) 19 57/60 (95%) 26/30 (87%) 8 54/60 (90%) 20/30 (67%) 23 47/60 (78%) 13/30 (43%) 35 58/60 (97%) 22/30 (73%) 24 24/60 (40%) 5/30 (17%) 23 34/50 (67%) 26/44 (59%) 8 32/50 (63%) 28/44 (63%) 39/50 (59%) 23/44 (52%) Collina et al., 2001 3 Broca’s patients 0 0 7 Caramazza and Hillis, 1991 2 fluent patients 17/30 (56%) 7/30 (22%) 34 29/30 (99%) 29/30 (97%) 2 De Bleser and Kauschke, 2003 5 Broca’s patients 4 fluent patients 33/36 (92%) 14/36 (39%) 53 30/36 (83%) 18/36 (50%) 33 31/36 (86%) 20/36 (56%) 30 34/36 (94%) 17/36 (47%) 47 34/36 (94%) 15/36 (42%) 52 29/36 (81%) 20/36 (56%) 25 35/36 (97%) 15/36 (42%) 55 34/36 (94%) 21/36 (58%) 36 30/36 (83%) 25/36 (69%) 14 54 Table 1 to be continued Study and patients Numbers correct naming objects Numbers correct naming actions Magnitude % of verb advantage Magnitude% of noun advantage De Renzi and Di Pellegrino, 1995 1 fluent patient 25/337 (7%) 83/94 (88%) 76/100 (76%) 62/100 (62%) 11/90 (12%) 43/60 (72%) 81 Druks and Carroll, 2005 1mixed patient 14 Hillis and Caramazza, 1995 1 fluent patient 60 Jonkers and Bastiaanse, 1996 38/60 (63%) 27/60 (45%) 18 46/60 (77%) 31/60 (52%) 25 51/60 (85%) 38/60 (63%) 22 53/60 (88%) 22/60 (37%) 51 61/62 (98%) 50/62 (81%) 17 60/62 (97%) 45/62 (73%) 24 52/62 (84%) 41/62 (66%) 18 58/62 (94%) 50/62 (81%) 13 57/62 (92%) 45/62 (73%) 19 61/62 (98%) 37/62 (60%) 38 53/62 (86%) 41/62 (66%) 20 32/36 (90% ) 28/36 (77%) 13 10 Broca’s patients 10 fluent patients Jonkers and Bastiaanse, 1998 2 fluent patients Kim and Thompson, 2000 7 Broca’s patients Kim and Thompson, 2004 9 Broca’s patients 55 Table 1 to be continued Study and patients Numbers correct naming objects Numbers correct naming actions Magnitude % of verb advantage Magnitude% of noun advantage Laiacona and Caramazza, 2004 1 fluent patient 22/52 (42%) 41/50 (82%) 40 1 Broca’s patient 47/52 (90%) 35/50 (70%) 20 15 Broca’s patients 20/30 (67%) 17/40 (43%) 24 36 fluent patients 15/30 (49%) 16/40 (41%) 8 176/204 (86%) 42/52 (81%) 5 8/28 (29%) 18/28 (64%) 38/42 (90%) 25/42 (59%) 31 29/70 (42%) 16/44 (36%) 6 50/70 (71%) 22/44 (50%) 21 47/70 (67%) 32/44 (73%) 55/70 (79%) 32/44 (72%) 7 44/70 (63%) 24/44 (55%) 8 Luzzatti et al., 20023 Marangolo et al., 1999 1 Broca’s patient Marshall et al., 1995/6 Part 2 1 fluent patient 35 Marshall et al., 1998 1 Broca’s patient Miceli et al., 1984 5 Broca’s patients 6 56 Table 1 to be continued Study and patients Numbers correct naming objects Numbers correct naming actions Magnitude % of verb advantage Magnitude% of noun advantage Miceli et al., 1984 5 fluent patients 8/70 (11%) 26/44 (59%) 48 19/70 (27%) 32/44 (73%) 46 27/70 (38%) 33/44 (75%) 37 48/70 (68%) 35/44 (80%) 12 48/70 (69%) 33/44 (75%) 6 Miceli et al., 1988 4 Broca’s patients 3 fluent patients 46/48 (96%) 18/36 (50%) 46 40/48 (83%) 13/36 (36%) 47 44/48 (92%) 27/36 (75%) 17 33/48 (69%) 9/36 (25%) 44 22/48 (46%) 23/36 (64%) 18 33/48 (69%) 31/36 (86%) 17 14/48 (29%) 18/36 (50%) 21 Miozzo et al., 1994 1 fluent patient 40/80 (50%) 63/80 (79%) 29 5/60 (8%) 11/30 (37%) 29 45/49 (92%) 29/49 (59%) 33 123/169 (73%) 26/109 (24%) 49 39/80 (49%) 38/50 (76%) Rapp and Caramazza, 2002 1 fluent patient Shapiro and Caramazza, 2003a 1 Broca’s patient Shapiro and Caramazza, 2003b 1 fluent patient Shapiro et al., 2000 1 fluent patient 27 57 Table 1 to be continued Study and patients Numbers correct naming objects Numbers correct naming actions Magnitude % of verb advantage Magnitude% of noun advantage Silveri and Di Betta, 1997 31/108 (29%) 63/104 (61%) 32 40/156 (26%) 71/152 (47%) 21 139/156 (89%) 108/152 (71%) 18 135/156 (87%) 82/152 (54%) 33 140/156 (90%) 89/152 (59%) 31 108/328 (33%) 157/328 (48%) 15 7/20 (35%) 17/20 (85%) 50 5 Broca’s patients 51/60 (85%) 17/30 (57%) 5 fluent patients 48/60 (80%) 24/30 (80%) 2 fluent patients 2 mixed patients Silveri et al., 2003 1 Broca’s patient Sörös, et al., 2003 1 fluent patient Zingeser and Berndt, 1988 1 fluent patient Zingeser and Berndt, 1990 28 0 0 58 Table 2: Number of patients in each clinical diagnosis and their object and action naming performance in the 38 studies reporting object and action picture data Clinical diagnosis Nouns = Verbs Noun < Verbs Verb < Nouns Broca’s 33 1 101 Fluent 7 30 104 Mixed 0 0 4 Total 40 31 209 59 Table 3: Summary of 27 studies that report large (30%+) noun-verb differences Study Diagnostic classification Lesion site 67/30 - Broca’s - n.a. 34 82/48 - Broca’s - n.a A4 51 83/32 - fluent - n.a. A6 40 80/40 - fluent - n.a. Bates et al., 1991 C13 56 88/32 - Broca’s - n.a. C32 40 83/43 - Broca’s - n.a. Berndt, et al., 2002 ML 33 89/56 - Broca’s - n.a. RE 48 83/35 - Broca’s - n.a. SC 33 70/37 - Broca’s - n.a. 47/77 - fluent - frontotemporooccipitoparietal, left Bastiaanse and Jonkers, 1998 Patients Verbs > Nouns (%) Nouns > Verb (%) Noun scores/Verb scores in % B5 37 B6 Berndt et al., 1997a SK 30 Berndt and Haendiges, 2000 JH 33 80/47 - fluent - basal ganglia. left Berndt et al., 1997b LR 52 92/40 - Broca’s - n.a. - - HF 34 49/83 - fluent - n.a. Bi, et al., (2005) ZBL 37 41/78 - fluent - medial temporal, lateral temporooccipital, occipital, left Bird et al., 2000 IB 36 73/37 - Broca’s - n.a. Breedin and Martin, 1996 LK 30 93/63 - Broca’s - frontotemporoparietal, left Breedin et al., 1998 LN 35 78/43 - Broca’s - frontotemporoparietal, left Caramazza and Hillis, 1991 HW 34 56/22 - fluent - occipital, parietal, left 60 Table 3 to be continue Study De Bleser and Kauschke, 2003 Patients Verbs > Nouns (%) Nouns > Verb (%) Noun scores/Verb scores in % Diagnostic classification Lesion site 5 53 92/39 - Broca’s - n.a. 6 33 83/50 - Broca’s - n.a. 7 30 86/56 - Broca’s - n.a. 8 47 94/47 - Broca’s - n.a. 9 52 94/42 - Broca’s - n.a. 3 36 94/58 - fluent - n.a. 2 55 97/42 - fluent - n.a. De Renzi and Di Pellegrino, 1995 Mario 81 7/88 - fluent - frontotemporal, left Hillis and Caramazza, 1995 EBA 60 12/72 - fluent - frontotemporoparietal, left Jonkers and Bastiaanse, 1998 TB 51 88/37 - fluent - internal capsule, white matter, left Kim and Thompson, 2000 BW 38 98/60 - Broca’s - Broca’s area, white matter, left Laiacona and Caramazza, 2004 EA 42/82 - fluent - temporal, left Luzzatti et al., 20025 AF 50 53/3 - Broca’s - insula, subcortical structures, left FC 57 87/30 - Broca’s - frontotemporal, left FM 30 70/40 - Broca’s - insula, subcortical structures, left LZ 32 70/38 - Broca’s - frontotemporal, left - frontotemporal, left 40 MB 48 83/35 - Broca’s 51 35 80/45 - Broca’s - n.a. 61 Table 3 to be continued Study Luzzatti et al., 2002 Patients Verbs > Nouns (%) CB FG Noun scores/Verb scores in % 32 38 MC PV Nouns > Verb (%) 65 45 Diagnostic classification Lesion site 47/15 - fluent - parietal, left 7/45 - fluent - left medial part of middle and inferior temporal gyri 73/8 - fluent - left posterior part of temporal lobe and inferior parietal gyrus 13/58 - fluent - inferior medial occipitotemporal, left RB 30 70/40 - fluent - left posterior part of temporal lobe and inferior parietal gyrus UB 39 87/48 - fluent - parietal, left 1 30 70/40 - fluent - n.a. 6 35 80/45 - fluent - n.a. 24 49 57/8 - fluent - n.a. 32 37 47/10 - fluent - n.a. FS 32 47/15 - mixed - insula, subcortical structures, left GP 32 70/38 - mixed - 58 48 53/3 - mixed temporal medial lobe, left - n.a. Marshall et al., 1995/6 Part 2 RG Marshall et al., 1998 EM Miceli et al., 1984 AA 35 29/64 - fluent - n.a. 90/59 - Broca’s - n.a. 48 11/59 - fluent - SF 46 27/73 - fluent temporoparietal, bilat. ML 37 38/75 - fluent - temporal, left - temporal, left 31 62 Table 3 to be continued Study Miceli et al., 1988 Patients Verbs > Nouns (%) Nouns > Verb (%) Noun scores/Verb scores in % Diagnostic classification Lesion site FDP 46 96/50 - Broca’s - 47 83/36 - Broca’s temporoparietal, left CS AM 44 69/25 - Broca’s - frontotemporal, right - frontotemporoparietal, left Shapiro and Caramazza, 2003a RC 33 92/59 - Broca’s - Broca’s area, prefrontal cortex, insula, internal capsule, anterior temporal, parietal operculum, left Shapiro and Caramazza, 2003b HG 49 73/24 - fluent - frontotemporal, basal ganglia, left Silveri and Di Betta, 1997 EO 29/61 - fluent - 87/54 - mixed temporoparietal, left - parietal white matter, external capsula, thalamus, left Silveri, et al., 2003 Zingeser and Berndt, 1988 32 SM 33 SA HY 31 50 90/59 - Broca’s - parietal, left 35/85 - fluent - left temporal and occipital lobe and inferior parietal lobe 63 Table 4: Lesion sites of 36 patients with large noun-verb differences for whom information about lesion site is available Lesion sites No. of patients in noun deficit group (n=12) No. of patients in verb deficit group (n=24) L. Broca’s area, prefrontal cortex, insula, internal capsule, anterior temporal, parietal operculum 1 L. Broca’s area, white matter 1 L. Internal capsule, white matter 1 L. Basal ganglia structures 1 L.parietal white matter, external capsule, thalamus 1 L. insula, basal ganglia, thalamus, external capsule 3 R. fronto-temporal 1 L. fronto-temporal 1 3 L. fronto-temporal, basal ganglia 1 L. Parietal 3 L. Occipito-parietal 1 L. Temporo-parietal 1 3 L. Fronto-temporo-parietal 1 3 L. medial middle and inferior temporal gyri 1 1 L. Temporo-occipito-parietal 1 L. Fronto-temporo-parietal-occipital 1 L. Temporal 3 Bilateral temporo-parietal 1 L.medial temporal, lateral temporooccipito, occipital 2 64 Table 5: Demographic information for the patients and comparison participants in the object and action picture naming study Patients Age Years of Sex school Controls Age Years of Sex school AB 83 10 F 1 83 10 F BG 51 15 F 2 51 18 F BM 76 9 M 3 72 11 F CH 38 16 F 4 36 19 F DOR 59 9.5 M 5 64 10 F HC 73 9 M 6 70 10 M LS 67 10 M 7 68 10 M PM 75 9 F 8 70 10 F SJ 52 13 F 9 52 21 F Mean 63.78 11.17 62.89 13.22 65 Table 6: Diagnostic and background information for the aphasic patients Patients Clinical diagnosis Aetiology MLU LU Words per minute Prop. of verbs Prop. of closed class words LS Wernicke’s aphasia CVA 4.51 13 90 0.59 0.60 PM Wernicke’s aphasia CVA 6.23 13 109 0.45 0.64 AB Broca’s aphasia CVA 2.93 8 44 0.37 0.53 BG Broca’s aphasia Haemorr- 5.07 13 88 0.20 0.29 BM Mixed CVA 4.67 10 125 0.4 0.37 DOR Mixed CVA 3.29 11 76 0.21 0.56 HC Mixed Tumour 4.5 15 43 0.37 0.60 CH Anomic CVA - - - - - SJ Transcort. motor aphasia CVA 3.96 11 40 0.35 0.49 hage 66 Table 7: Summary item characteristics for the object and action pictures (standard deviations are in brackets) Picture type objectsnouns actionsverbs AOA 2.57 (0.67 2.56 (0.66) K-F Frequency 56.24 977.75 80.87 (100.69) Familiarity ImageabilityVisual Syllable complexity length 3.67 5.83 3.49 1.47 (1.48) (0.55) (1.28) (0.66) 3.98 4.23 4.23 2.05 (1.40) (0.58) (0.76) (0.22) 67 Table 8: Mean naming latencies in msecs (st.dev. in brackets) for the object and action pictures for the patients’ and comparison group Actions Actions minus Objects 2412 3418 1006 (1133) (1999) Comparison 1171 1285 group (283) (296) Objects Patients 114 68 Table 9: Number of errors in object and action naming made by the patients and the comparison group Patients Objects (n=100) Actions (n=100) AB BG BM CH DOR HC LS PM SJ Patients Controls Total Total 6 1 6 7 23 13 11 10 1 78 23 13 5 18 17 31 26 20 41 26 197 46 69 Table 10: Number (%) of errors made to the object and action pictures organized according to error type Error type Example Objects Actions N= 80 (%) N= 201 (%) 25 (31) 16 (8) 2 (2.5) 2 (1) 2 (2.5) 0 12 (15) 10 (5) 4 (5) 2 (1) Semantic co-ordinate washing → not shaving; climbing → jumping button→ not a pin; triangle → oblong super-ordinate nun → lady bouncing → making a ball sub-ordinate bird → robin associative door → a key; hammock → camping floating → lost at sea; watering → growing Visual frank visual leaf → feather; comb → music score yawning → laughing; bending → sneezing misinterpretation of the picture cooking → chef 48 (24) kicking → ball; picnic → picnic basket button → a round circle with four dots N errors 20 (25) 54 (27) waiter → man carrying a tray other pulling → running with elephant Other circumlocution grapes → wine.. you making out of this; roots → not tree but down 6 (7.5) sinking → ship is going under the water; begging → beggar with a hand out phonological errors 29 (14.4) beard → bear; axe → ash(e)s 2 (2.5) 4 (2) 7 (9) 36 (18) weaving → wealving; raking → graping no response climbing → haven’t got a clue circle → I can’t... no 70 Acknowledgements We are grateful to the patients and the control participants for taking part in the study, and to Michael Coleman and Gordon Craig for their assistance. The paper is dedicated to the memory of SJ, who sadly died shortly after completing her participation in this study. 71 72