Semantic and Visual Determinants of Face Recognition in a Prosopagnosic Patient Mike J. Dixon University of Waterloo, Canada Daniel N. Bub University of Victoria, Canada Martin Arguin Université de Montréal, Canada. Abstract ■ Prosopagnosia is the neuropathological inability to recog- nize familiar people by their faces. It can occur in isolation or can coincide with recognition deªcits for other nonface ob- jects. Often, patients whose prosopagnosia is accompanied by object recognition difªculties have more trouble identifying certain categories of objects relative to others. In previous research, we demonstrated that objects that shared multiple visual features and were semantically close posed severe rec- ognition difªculties for a patient with temporal lobe damage. We now demonstrate that this patient’s face recognition is constrained by these same parameters. The prosopagnosic pa- tient ELM had difªculties pairing faces to names when the faces shared visual features and the names were semantically related (e.g., Tonya Harding, Nancy Kerrigan, and Josée Chouinard— three ice skaters). He made tenfold fewer errors when the exact same faces were associated with semantically unrelated people (e.g., singer Celine Dion, actress Betty Grable, and First Lady Hillary Clinton). We conclude that prosopagnosia and co-occurring category-speciªc recognition problems both stem from difªculties disambiguating the stored representations of objects that share multiple visual features and refer to seman- tically close identities or concepts. ■ INTRODUCTION Prosopagnosia is the neuropathological inability to rec- ognize familiar people by their faces. The temporal lobe patient ELM, for example, is unable to recognize the faces of his wife, sons, or grandchildren. He claimed a picture of the ªrst author was unfamiliar, despite sitting immediately beside him. Prosopagnosic patients can have intact perception. ELM can copy complex ªgures and animals. He can name photographs of objects taken from both standard and unusual views. He can match standard and unusual views of animals and artifacts and can select a target face from an array of distractor faces surrounding the target. De- spite these intact perceptual abilities, over several years of testing ELM has never once spontaneously identiªed a single face. He cannot discriminate familiar from unfa- miliar faces or previously viewed faces from novel unfa- miliar ones, nor can he identify emotional expressions. (A more complete case report is given in the “Subjects” and “Methods” section following the discussion.) Prosopagnosia patients can vary in the severity of their face recognition deªcits. The prosopagnosia patient PV (Sergent & Poncet, 1990) was tested on a two alter- native, forced-choice, face-name-matching test in which a face was presented along with the correct name and another name referring to a person of the same gender and occupation as the correct alternative. PV selected the correct name on 40 out of 48 trials. By contrast, ELM performed at chance levels on this same task (20/48 trials correct). Prosopagnosic patients can also vary as to whether or not they display covert face recognition. Covert recogni- tion refers to the fact that although patients cannot spontaneously name a face or pick the right name for a face from a set of names, using certain indirect behav- ioral measures (evoked potentials, galvanic skin re- sponse, semantic priming, and learning of true and untrue face-name pairings), some patients do show a certain degree of intact recognition (see Young, 1994, for a review). In a covert recognition paradigm using seman- tic priming Young, Hellawell, and De Haan (1988) asked the patient PH to make speeded familiarity judgments to printed names (e.g., John Lennon). The name was pre- ceded by a related face (e.g., Paul McCartney), an unre- lated face (Ronald Reagan), or a neutral unfamiliar face. Despite PH’s inability to overtly identify these faces, his reaction times for the related condition (1016 msec) were signiªcantly faster than the neutral (1080 msec) and unrelated conditions (1117 msec). On a variant of Young et al.’s (1988) semantic priming task (using the related and unrelated but not the neutral condition), ELM showed no priming, and was actually marginally faster at saying a name was familiar when an © 1998 Massachusetts Institute of Technology Journal of Cognitive Neuroscience 10:3, pp. 362–376