Holistic face perception impairment in acquired prosopagnosia as evidenced by eye-gaze-contingency: Generalization to several cases

Abstract

Gaze-contingency is a method introduced by Rayner (Cog. Psy., 1975) to investigate the perceptual span in reading by selectively revealing/masking a portion of the visual field in real time. Recently, we introduced this approach in the field of face perception, showing that a brain-damaged patient with impairment limited to face recognition (acquired prosopagnosia, patient PS) presents with the reverse pattern as normal observers: almost no further decrease of performance when only one feature at a time is available (foveal window condition), but a very large impairment when the fixated feature is masked (mask condition), forcing holistic perception (Van Belle et al., JOV 2009: http://www.journalofvision.org/content/9/8/541; Neuropsychologia, 2010). Here we extend these latter observations to two cases of acquired prosopagnosia with unilateral right hemisphere damage: GG (Busigny et al., Neuropsychologia, 2010; lingual, fusiform and parahippocampal damage) and LR (Bukach et al., J. Cogn. Neurosci., 2006; anterior pole damage). Both patients also present with impairment in visual recognition limited to faces. They were tested in a delayed face matching task with a full view, gaze contingent window, and gaze contingent mask condition. Similar to PS and contrary to normal observers, both patients were significantly more impaired with a mask than with a window, demonstrating problems with holistic face perception. These observations support a generalized account of acquired prosopagnosia as a selective impairment of holistic face perception, and imply that holistic perception is a key element of normal human face recognition. Furthermore, the similar behavioral pattern of all three patients despite their very different lesion locations supports a distributed network view of the neural face processing structures, meaning that the key function of face perception requires the activity of several brain areas of the right hemisphere and their mutual connectivity.

Bruno Rossion, Goedele Van Belle and Thomas Busigny were supported by the Belgian National Fund for Scientific Research (Fonds Nationale de la Recherche Scientifique FNRS). Philippe Lefère was supported by the Fonds National de la Recherche Scientifique, the Fondation pour la Recherche Scientifique Medicale, the European Space Agency (ESA,European Union), and Prodex grant C90232 from Belspo (Belgian Science Policy).