Cognitive Neuropsychology

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Dissociations between the Processing of Proper and Common Names Serge Bredart; Tim Brennen; Tim Valentine Online Publication Date: 01 March 1997 To cite this Article: Bredart, Serge, Brennen, Tim and Valentine, Tim (1997) 'Dissociations between the Processing of Proper and Common Names', Cognitive Neuropsychology, 14:2, 209 - 217 To link to this article: DOI: 10.1080/026432997381556 URL: http://dx.doi.org/10.1080/026432997381556

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COGNITIVE NEUROPSYCHOLOGY, 1997, 14 (2), 209–217

Dissociations between the Processing of Proper and Common Names Serge Brédart University of Liège, Belgium

Tim Brennen University of Tromsø, Norway

Tim Valentine Goldsmiths College, University of London, UK Recently, some authors have claimed that a double dissociation between an “anomia for proper names” and a “selective sparing of proper names” has been demonstrated in the cognitive neuropsychology literature (e.g. Cohen & Burke, 1993; Hittmair-Delazer,Denes, Semenza, & Mantovan, 1994; Semenza & Zettin, 1989). The aim of the present paper is to evaluate whether this claim is really tenable or not. We point out the need to distinguish carefully between the production and comprehension of language when looking for such a dissociation. We argue that a double dissociation between the processing of proper names and common names has not been demonstrated for production. The evidence for a double dissociation between comprehension of proper names and common names is much stronger, but even this claim is limited.

Several cases of selective impairment of the production of proper names have been reported in the literature. Two of them, described by Semenza and Zettin (1988, 1989), presented an impairment of the production of both people’s names and names of geographical sites (rivers, mountains, towns, etc.). The other patients showed a still more specific impairment, which was restricted to the production of people’s names (Carney & Temple, 1993; Fery, Vincent, & Requests for reprints should be addressed to Dr. Serge Brédart, University of Liège, Cognitive Psychology (B-32), B-4000 Liège 1, Belgium (e-mail: [email protected]). This work was supported by a grant awarded to Tim Valentine from the Economic and Social Research Council (no. R000234612). The authors wish to thank Michael McCloskey and two anonymous referees for their helpful comments on a previous version of the manuscript.

Ó 1997 Psychology Press, an imprint of Erlbaum (UK) Taylor & Francis Ltd


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Bréd art, 1995; Hittmair-Delazer et al., 1994; Lucchelli & De Renzi, 1992; McKenna & Warrington, 1980). Three characteristics are shared by these patients: 1. An anomia for proper names or an anomia for people’s names. 2. Their ability to produce common names is preserved, or shows very little impairment, for all categories of common names investigated. 3. They show no deficit in the comprehension of either proper names or common names. The main issue of this paper is to determine whether the mirror imagepattern of performance has been described in a neuropsychological case study. A “pure” example of such a case would be a patient who is reported with an anomia for common names and no comprehension deficit. It is important to establish whether or not comprehension is impaired in such a patient. Indeed, if a patient has a comprehension deficit as a result of damage to the semantic system, this comprehension deficit would underpin the naming deficit. This point will be developed further later in the paper. A corollary issue, discussed later, concerns dissociations between the comprehension of common and proper names. The issue of whether or not such patients exist has implications for models of the lexicon. If they do indeed exist then double dissociation logic suggests that the processing routes, following conceptual processing, for production of proper and common names are (at leastpartially)independent, and proper name and common name retrieval could proceed in parallel. Alternatively, if cases with common name anomia and proper name preservation do not exist then it is more parsimonious to suppose that retrieval of proper and common names use the same procedures. A number of theories can account for the single dissociation, reported earlier, where proper names are more difficult to recall than common names (e.g. the theory of arbitrariness, Cohen, 1990; the “degree of freedom” explanation, Brédar t, 1993; the “set size of plausible phonology” hypothesis, Brennen, 1993; see Valentine, Brennen, & Bréda rt, 1996, for a review). To begin with, we find that whereas there are case studies with dissociations between proper and common name processing, including preservation of proper names, there are none that provide evidence for the particular dissociation that would suggest that proper and common name production are served by different routes. Our reading of the literature is thus in contrast to other authors’, who have claimed that there is a double dissociation between proper and common name processing. As Brennen (1993) pointed out, Semenza and Zettin (1989) cite patient YOT, described by Warrington and McCarthy (1987), as forming a double dissociation with their patient, LS, who showed an anomia for proper


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names. However, YOT’s preserved abilities included the comprehension of proper names and some classes of common names. YOT is described by Warrington and McCarthy as “totally unable to produce any propositional speech.” YOT does not show either a preserved ability to produce proper names in the context of an impairment to production of common names, or preserved comprehension of both proper names and common names. Hittmair-Delazer et al. (1994) cite three patients who, they claim, show a selective sparing of proper names. We shall consider each patient in turn. The first patient was FC, described by McKenna and Warrington (1978). FC was an aphasic patient who showed important naming difficulties; his scores of naming in a visual presentation task varied from 0 to 5/20 for categories such as colour, objects, and animals. In comparison, his score in naming countries reached 13/20. This would appear to indicate preserved naming of one category of proper names. However, naming of body parts was also relatively wellpreserved (10/20). Naming body parts requires the retrieval of common names. Thus, the naming of two categories were relatively spared: countries and body parts. One of them required the production of proper names, the other the production of common names. Naming of body parts was more accurate than production of common names denoting other categories. Moreover, and unfortunately, the production of proper names other than names of countries was not investigated in this study. It would be quite possible that naming countries was a preserved island in the production of proper names, in the same way that production of body parts was a preserved island in the production of common names. This could be quite possible, as the authors reported the anecdote that, when trying to name Ghandi, the patient responded “India.” The authors also used a naming from description task, in which FC scored very poorly (0 to 4/20) for the different categories of common names while his score reached 15/20 for country names. But this result is difficult to interpret, because FC presented comprehension difficulties in neuropsychological testing. From the data available, it is very difficult to state that this patient did show a pure preservation of the production of proper names. The second patient (RI) was a jargonaphasic patient described by Semenza and Sgaramella (1993). Hittmair-Delazer et al. wrote that RI was “a case of phonemic jargon, where persons’ names were the only spared elements in both spontaneous speech and naming tasks.” This claim requires some comment. First, people’s names seemed to emerge randomly in RI’s discourse. Second, RI was unable to name any person (relatives, friends, famous people) on visual confrontation or from definition. The relative sparing of proper name retrieval is demonstrated through a cued naming task. When the first sound of a target name was given, RI’s performance improved for people’s names but not for common names. Although this is an intriguing result, it is difficult to interpret. It is, however, clear that the pattern of difficulties presented by this patient is not an anomia for common names with preserved proper name recall and is


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therefore not the opposite pattern to proper name anomia. Semenza and Sgaramella (1993, pp. 274, 277), however, claim that RI represents “the complementary side of a double dissociation: selective spared production of proper names vis-à-v is the selective impairment of production already reported in the literature” and that “RI’s disorder would be a mirror image of proper name anomias where the proper names channel seems to be cut out.” However, RI’s performance deviates in many ways from the mirror image of proper name anomia: Most importantly, the patient named nothing to confrontation. The third patient, MED, was severely aphasic (Cipolotti, McNeil, & Warrington, 1993). Her naming performance in the oral modality was difficult to assess due to articulation difficulties. Her production of common and proper names was investigated in the written modality. This patient showed spared naming of countries and famous people whereas her object naming performance was impaired. At first sight this pattern seems to be the opposite to proper name anomia. However, it is difficult to know whether MED had difficulties of comprehension of common names. Indeed, in Cipolotti et al.’s paper, her comprehension assessed through matching spoken words to pictures seems to be spared. However, impaired comprehension of common names is described in the same patient in another paper (McNeil, Cipolotti, & Warrington, 1994). We have already mentioned that it is important to establish whether or not comprehension of common names is impaired. If MED had a comprehension deficit as a result of damage to the semantic system per se, current cognitive models would predict a naming deficit for common names (e.g. names of objects; see Bock & Levelt, 1994; Bruce & Young, 1986; Humphreys, Riddoch, & Quinlan, 1988; Seymour, 1979). In these models one must access the semantic system before one can access the name of an object. If one has a comprehension deficit for a certain category because the relevant part of the semantic system is deficient, then the names of things in that category would also be inaccessible. The comprehension deficit would underpin the naming deficit. That is, even if the names of objects were intact they would be unrecallable. Thus if MED has a comprehension deficit for common names, it would also underpin her naming deficit for common names and it would be wrong to draw conclusions about lexical processing from such a patient. As we saw earlier, McNeil et al. (1994) did report comprehension difficulties for this patient. The interpretation of MED’s pattern of impairment is further complicated by the fact that data were collected while her state deteriorated very quickly during the study. The neuropsychological investigationtook place over a period of 11 days. Spoken word to picture matching was intact at first but degraded over the period of testing. Her naming (oral and written) was impaired at first, and by the end of testing was reduced to almost nil. In summary, a number of patients showing a selective impairment in production of proper names has been reported, but Hittmair-Delazer et al.’s



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(1994) claim, that cases of a selective impairment in production of common names in the context of preserved production of proper names have also been reported, is, at best, overstated. The most reasonable conclusion of a review of the literature is that there are no cases of common name anomia that constitute the mirror image to proper name anomia.

Theoretical Models of the Production of Proper Names and Common Names If a double dissociation between production of proper names and common names can be demonstrated in the future, could this result be accommodated by existing theoretical models? The framework proposed by Valentine, Brédar t, Lawson, and Ward (1991) includes a single output lexicon, which is accessed in production of common names and people’s names (other classes of proper names are not explicitly addressed by this framework). However, production of people’s names and common names require access to the output lexicon via separate pathways. Therefore, a double dissociation between production of people’s names and common names could be explainedby selectiveattenuation (or disconnection) of either the pathways from person identity nodes (token markers in memory for known individuals) to the output lexicon or the pathways from semantic memory to the output lexicon. Valentine et al. (1996) develop this framework considerably to account for a wider range of data. However, the new framework retains separate access to the output lexicon for people’s names and common nouns. If a double dissociation can be accommodated by the theoretical models, the question arises of why a clear case of selective impairment in production of common names with preserved production of people’s names has not yet been reported. In our view, although structurally possible within our favoured model, the chances of a case with stable common name anomia and proper name preservation are extremely small because of the large number of reasons why proper name retrieval is essentially more difficult than common name retrieval. The body of data from normal subjects in favour of this view is reviewed in Valentine et al. (1996). Valentine et al. also offer a detailed review of theories explaining why proper names are more difficult to recall than common names. Here we will describe one such account, in terms of Node Structure Theory and proposed by Burke, MacKay, Worthley, and Wade (1991). In order to explain why proper names evoke more tip-of-the-tongue states than common names, Burke et al. suggest that production of a person’s name requires activation to be passed via a single link from a token marker to a node representing a person’s full name. However, there are many links between semantic features and a lexical node for a common name. Therefore, production of proper names is much more vulnerable to retrieval failure because failure of a single link will be sufficient to produce a


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naming difficulty. In the case of common names, failure of a single link will not have a noticeable effect as activation can be passed by links between other semantic features and the output lexicon.

Double Dissociation in the Comprehension of Proper Names and Common Names The conclusion of the first part of this paper was that there have been no reports of patients with common name anomia and proper name preservation. This section reviews the literature concerning comprehension of proper and common names, with the same goal, to determine whether there are grounds for suggesting that there is a double dissociation between the comprehension of proper and common names. Models of semantic memory suggest that it is organised categorically. Some of the strongest evidence for this comes from category-specific deficits of the semantic system. Semantic deficits have been reported for many categories, e.g. living things, nonliving things, body parts, colours. It would thus be consistent with these results if it were also possible to lose the ability to comprehend everyday objects, while remaining able to comprehend famous faces or another category whose exemplars are referred to by proper names. Indeed, in tests of comprehension, there are a number of reported cases of preserved comprehension of proper names in the context of impaired comprehension of common names. Van Lancker and Klein (1990) report case studies of four patients who acquired global aphasia following left-hemisphere brain damage. Their ability to recognise proper names was assessed by requiring the patients to select the photograph from an array of four famous faces that matched a spoken or written name. Although all of the patients were severely impaired in their ability to recognise common nouns, as assessed by standardised tests, they performed within the normal range when matching famous faces to spoken names and to names that were presented both verbally and visually. The same pattern of preserved proper name matching in the presence of impaired common noun matching was found when subjects were asked to select the appropriate name or word from an array of four written responses to match either a spoken or pictured object or celebrity. In terms of Valentine et al.’s (1991) framework, the dissociation reported by Van Lancker and Klein (1990) could arise from impaired access to semantic information from word recognition units in the context of unimpaired access to identity-specific semantic information via name recognition units. The impairment could either be to the links from word recognition units to units representing semantic information, or to the semantic units themselves. Impairment to the links would give rise to modality-specific impairment as there are assumed to be separate sets of word recognition units for auditorily presented and visually presented words. However, Van Lancker and Klein’s patients were



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impaired in their comprehension of both seen and heard words. This pattern of impairment is consistent either with damage to the semantic information units or to impaired access to the semantic system from both auditory and visual word recognition systems. On the grounds of parsimony, damage to the semantic system per se should be the preferred interpretation. As it is assumed that there is a single multi-modal semantic system, damage to the units representing semantic information alone would result in an impairment to comprehension of both written and spoken words. Consistency of errors to specific items across different test sessions is often taken as indicative of damage to the semantic representations as opposed to impaired access. Unfortunately, Van Lancker and Klein did not report any such data. The opposite dissociation of impaired recognition of proper names in the context of unimpaired processing of common nouns and other word categories could occur if the access to identity-specific semantics is impaired while access to the rest of the semantic system remains unimpaired. If Van Lancker and Klein’s (1990) patients are interpreted as suffering from an impairment to the representation of semantic information, cases forming a possible double dissociation have been reported in the literature. De Haan, Young, and Newcombe (1991); Ellis, Young, and Critchley (1989); Hanley, Young, and Pearson (1989) report patients who suffer impaired access to identity-specific semantic information that is not modality-specific in the context of unimpaired word recognition skills. These patients are unable to recognise the names or faces of familiar people. The patient (BD) reported by Hanley et al. (1989) showed impaired access to identity-specific information about people in the context of more general impairment to semantic memory about living things. Therefore, BD does not show a dissociation between semantic memory for the referents of proper names and common names. Patient ME, reported by De Haan et al. (1991), had a pure amnesic syndrome with severe anterograde and retrograde long-term memory loss. Nevertheless, she did show a dissociation between semantic memory for people and other entities. Language comprehension, production, and object naming were normal. No assessment of performance in understanding referents of proper names other than people was reported. Patient KS, reported by Ellis et al. (1989), provides the clearest case forming a double dissociation to patients reported by Van Lanckerand Klein (1990). She suffered from a severe loss of memory for people but was not amnesic and did not show a generaliseddeficit of semantic memory for living things. However, her deficit did extend to famous animals, famous buildings, and product names. Both Hanley et al. and Ellis et al. analysed the consistency of errors and reported consistency coefficients from test sessions several months apart that were in the range of .35–.47. These figures show a reasonable degree of consistency but are not particularly high. (Perfect consistency would yield a coefficient of .707 in these cases.)


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It should be noted that Van Lancker and Klein did not test categories of proper names other than people’s names, so we are unable to conclude for tests of comprehension whether the double dissociation is between processing of all categories of proper names and common names or between processing people’s names and common names. We can conclude that it is possible to have a preserved island of proper name comprehension with severe problems with common name comprehension, and that it is possible to have a selective deficit of comprehension of a range of categories of proper names. This is entirely consistent with the uncontroversial assumption that semantic memory is categorically organised. A final note of caution in the interpretation of the data obtained from aphasic patients needs to be considered. The interpretation of the patients’ deficits are based on the assumption that word-object matching, face-name matching, or auditory-visual word or name matching demonstrates “comprehension.” However, this need not necessarily be the case. In Burton, Bruce, and Johnston’s (1990) connectionist model of person identity processing, face and name matching could be achieved at the level of the person identity nodes without any access to identity-specific semantics. Indeed, ME showed the preserved ability to match a famous face with the appropriate name, although she was unable to provide any identity-specific semantic information about the relevant celebrity (De Haan et al., 1991). Had her comprehension of people’s names been tested using only the matching technique employed by Van Lancker and Klein, she would have appeared to comprehend people’s names. The interpretation we have described would predict that patients reported by Warrington and McCarthy (1987) and Van Lancker and Klein (1990) are able to access person identity nodes. We don’t know, however, whether they “comprehend” the people’s names in the sense of being able to retrieve identity-specific semantics. In order to address this issue it would be necessary to test whether such patients can classify people’s names according to their occupational category or whether they are dead or alive, for example. It is only really justifiable to use the term “comprehension” if the patients are able to perform such semantic classification tasks. No such problems of interpretation apply to the data which demonstrate preserved comprehension of common names accompanied by deficits in comprehension of proper names. As these patients are not aphasic they are able to name objects from pictures or from definition. Manuscript received 8 September 1995 Revised manuscript received 27 August 1996 Manuscript accepted 19 September 1996

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