The Early Time Course of Compensatory Face Processing in Congenital Prosopagnosia
Rainer Stollhoff, Jürgen Jost, Tobias Elze, and Ingo Kennerknecht
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Submission date: 10. Feb. 2010
published in: PLOS ONE, 5 (2010) 7, art-no. e11482
DOI number (of the published article): 10.1371/journal.pone.0011482
Keywords and phrases: Prosopagnosia, Face Recognition
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Prosopagnosia is a selective deficit in facial identification which can be either acquired, (e.g. after brain damage), or present from birth (congenital). Previously, the face recognition deficit in prosopagnosia has been characterized by worse accuracy, longer reaction times, more dispersed gaze behavior and a strong reliance on featural processing. Here, we portray compensatory processing in congenital prosopagnosia as a serial inspection of diagnostic features.
We investigated performance differences in different face and shoe identification tasks between a group of 16 participants with congenital prosopagnosia and a group of 36 age-matched controls. Given enough training and unlimited stimulus presentation prosopagnosics could achieve normal face identification performance albeit at the expense of longer reaction times. This increase in reaction times can be accounted for by an equally-sized increase in stimulus presentation times needed by prosopagnosics to perform at the same level as controls. Reversely, as the inspection time of face stimuli was limited by tachystocopic presentation, prosopagnosics only showed worse performance but differences in reaction time vanished. Thus, prosopagnosics inspect faces longer but require a normal amount of time to make and execute the decision. In a further experiment, rotation of face stimuli away from the learned frontal viewed decreased recognition performance for both groups similarly. All group differences in performance, reaction or presentation times, and the influence of rotation were selective to face stimuli and didnt extend to shoes.
Our study provides a characterization of congenital prosopagnosia in terms of early processing differences. More specifically, compensatory processing in congenital prosopagnosia requires an inspection of faces that is sufficiently long for sequential focusing on diagnostic features. Our characterization of dysfunctional processing in prosopagnosia further emphasizes fast and holistic information encoding as the defining characteristic of normal face processing.