The fur of the crocodile and the mooing sheep: A study of a patient with a category-specific impairment for biological things

Abstract

We report a single case study of a brain-damaged patient, ER, who showed a remarkably consistent category-specific deficit for living things. His impairment was observed across tasks (naming, definition, matching, drawing from memory, questionnaires), input modalities (visual, verbal, nonverbal auditory), and output modalities (verbal vs. pointing or visual matching responses) as well as for different types of knowledge. Although visual knowledge of living things was severely affected, his category-specific impairment in nonverbal sound recognition is inconsistent with models of category-specific deficits based on pre-semantic visual descriptions. ER's deficit cannot fully be explained by item typicality, word frequency, visual complexity, homomorphy, age of acquisition, value to perceiver, or modality of transaction. Furthermore, in ER, contextual cues were even slightly detrimental for the recognition of animals. ER's naming and recognition errors were constrained by the categorical structure of the knowledge base: In most cases they respected both the second-and first-order superordinates. In particular, ER's knowledge of shared categorical properties related to biological function was almost spared. This result is compatible with the idea that, for living things, shared functional properties and shared perceptual properties are strongly correlated. Feature-based models assuming perceptual vs. functional semantic components cannot account for ER's deficit, since for living things he was impaired on both kinds of features to a similar extent. ER's behaviour is quite consistent with the notion that conceptual knowledge is organised categorically in the brain, with one or several specialised subsystems for biologically related entities. 301Requests for reprints should be addressed to Régine Kolinsky, Unité de Recherche en Neurosciences Cognitives (UNESCOG), Université Libre de Bruxelles, CP 191, Av. F.D. Roosevelt, 50, B-1050 Brussels, Belgium (Fax: 32-2-650.22.09; Email: rkolins@ulb.ac.be).We wish to thank Tim Shallice for very helpful discussions on a former version of the manuscript, as well as the Editor and two anonymous reviewers for their very constructive comments. We also thank all the people who participated in the present study, including the members of the Research Unit in Cognitive Neuroscience and of the Laboratoire de Psychologie Expérimentale of the Université Libre de Bruxelles, who were prepared to spend several hours filling in questionnaires. This work was supported by A.F.R.F.C.-F.N.R.S. grant. Downloaded by [Archives & Bibliothèques de l'ULB] at 06:20 10 July 2015The observation of specific semantic memory disorders, i.e., that some patients exhibit a selective loss of knowledge of items from certain categories, for example biological (or living) entities, by comparison with nonbiological (or non-living) objects, has generated a large debate about the internal organisation of the semantic system (see recent reviews, e.g., in Caramazza, 1998;Forde & Humphreys, 1999;Humphreys & Forde, 2001;...

Statistiques appliquées aux études de cas unique : méthodes usuelles et alternatives

“…Il n'est pas rare de voir dans la littérature en neuropsychologie des échantillons de sujets témoins comprenant un effectif inférieur à 15 [8][9][10][11][12][13][14][15][16]. En règle générale, les participants témoins sont appariés sur différentes variables (âge, niveau d'étude, sexe, etc.)…”

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“…La tarea de los participantes consiste en denominar el ítem mostrado. Existen diferentes versiones de la tarea de denominación, por ejemplo, denominación de dibujos coloreados (Montanes, Goldblum y Boller, 1995); de fotografías en color (Bunn, Tyler, y Moss, 1998;Moreno y Cañamón, 2005); de sonidos procedentes de diferentes SV y SNV (Caramazza y Shelton, 1998); de sustancias comestibles y no comestibles (Borgo y Shallice, 2001); de objetos reales (Forde, Francis, Riddoch, Rumiati y Humphreys, 1997); de líquidos, tanto bebestibles como no bebestibles (Borgo y Shallice, 2001); así como de animales filmados en su ambiente natural (Kolinsky et al, 2002). También existe una versión llamada denominación tras descripción, en ella el paciente debe denominar el ítem después de que el experimentador lo ha descrito verbalmente (Hodges et al, 1995;Moreno y Cañamón, 2005).…”

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“…Los pacientes con deterioro perceptivo no consiguen distinguir un objeto real de otro irreal; también suelen confundir la parte que le falta al estímulo; por ejemplo, encajan la cabeza de un pato en el cuerpo de un ciervo. Cuando las dificultades son de tipo semántico, los pacientes suelen presentar deterioro en algún dominio semántico, por ejemplo, muestran deterioro de los SV y un buen rendimiento con los SNV (Kolinsky et al, 2002).…”

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