The cognitive neuroscience of person identification.

We compare and contrast five differences between person identification by voice and face. 1. There is little or no cost when a familiar face is to be recognized from an unrestricted set of possible faces, even at Rapid Serial Visual Presentation (RSVP) rates, but the accuracy of familiar voice recognition declines precipitously when the set of possible speakers is increased from one to a mere handful. 2. Whereas deficits in face recognition are typically perceptual in origin, those with normal perception of voices can manifest severe deficits in their identification. 3. Congenital prosopagnosics (CPros) and congenital phonagnosics (CPhon) are generally unable to imagine familiar faces and voices, respectively. Only in CPros, however, is this deficit a manifestation of a general inability to form visual images of any kind. CPhons report no deficit in imaging non-voice sounds. 4. The prevalence of CPhons of 3.2% is somewhat higher than the reported prevalence of approximately 2.0% for CPros in the population. There is evidence that CPhon represents a distinct condition statistically and not just normal variation. 5. Face and voice recognition proficiency are uncorrelated rather than reflecting limitations of a general capacity for person individuation.

An estimate of the prevalence of developmental phonagnosia.

A web-based survey estimated the distribution of voice recognition abilities with a focus on determining the prevalence of developmental phonagnosia, the inability to identify a familiar person based on their voice. Participants matched clips of 50 celebrity voices to 1-4 named headshots of celebrities whose voices they had previously rated for familiarity. Given a strong correlation between rated familiarity and recognition performance, a residual was calculated based on the average familiarity rating on each trial, which thus constituted each respondent's voice recognition ability that could not be accounted for by familiarity. 3.2% of the respondents (23 of 730 participants) had residual recognition scores 2.28 SDs below the mean (whereas 8 or 1.1% would have been expected from a normal distribution). They also judged whether they could imagine the voice of five familiar celebrities. Individuals who had difficulty in imagining voices were also generally below average in their accuracy of recognition.

Developmental phonagnosia: Neural correlates and a behavioral marker.

A 20-year old female, AN, with no history of neurological events or detectable lesions, was markedly poorer than controls at identifying her most familiar celebrity voices. She was normal at face recognition and in discriminating which of two speakers uttered a particular sentence. She evidences normal fMRI sensitivity for human speech and non-speech sounds. AN, and two other phonagnosics, were unable to imagine the voices of highly familiar individuals. A region in the ventromedial prefrontal cortex (vmPFC) was differentially activated in controls when imagining familiar celebrity voices compared to imagining non-voice sounds. AN evidenced no differential activation in this area, which has been termed a person identity semantic system. Rather than a deficit in the representation of voice-individuating cues, AN may be unable to associate those cues to the identity of a familiar person. In this respect, the deficit in developmental phonagnosia may bear a striking parallel to developmental prosopagnosia.