Face Processing In Prosopagnosia Research Articles

Gaze-contingent techniques reveal impairment of holistic face processing in acquired prosopagnosia

Normal observers process individual faces holistically, meaning that facial features are processed simultaneously over a face-wide perceptual span and that the face is represented as a single perceptual unit. Acquired prosopagnosia, an impairment of face recognition following brain damage is thought to be caused by a problem with holistic processing of faces (Sergent & Villlemure, 1989). However, previous studies have only demonstrated an impairment of interactive processing of features in patients who, in addition, present general visual integrative agnosia (e.g., Boutsen & Humphreys, 2002; Levine & Calvanio, 1989), so that direct evidence for a deficit in holistic face processing in prosopagnosia is lacking. In an experiment with a brain damaged case of prosopagnosia (PS, Rossion et al., 2003), we used two gaze-contingent techniques allowing manipulation of the amount of information that was simultaneously available. First, a gaze-contingent foveal mask, prevented the use of foveal, high resolution information, necessary for detailed investigation of the facial features, but allowed holistic processing based on lower resolution peripheral information. Second, a gaze-contingent foveal window covering all peripheral information, prevented the simultaneous use of several facial features, but allowed detailed investigation of each feature individually. In a face matching task, normal control participants showed increased errors and RTs with a foveal window in comparison to conditions with a foveal mask or with a full face. PS, on the contrary, was almost unimpaired by a foveal window relative to a full face, while she had major difficulties recognizing faces with a foveal mask. Moreover, the eye movement data confirmed the findings from previous studies, that for face recognition, PS mainly relies on the mouth region, while normal observers attend to the region just below the eyes. These data provide direct evidence for impairment of holistic face processing in acquired prosopagnosia.

Facial attraction: a study of the aesthetic dimension of face processing in prosopagnosia

Facial attraction: a study of the aesthetic dimension of face processing in prosopagnosia

The effects of rotation and inversion on face processing in prosopagnosia

The current study investigated the sensitivity of face recognition to two changes of the stimulus, a rotation in depth and an inversion, by comparing the performance of two prosopagnosic patients, RN and CR, with non-neurological control subjects on a face-matching task. The control subjects showed an effect of depth rotation, with errors and reaction times increasing systematically with rotation angle, and the traditional inversion effect, with errors and reaction times increasing under inverted conditions. In contrast, RN showed no effect of rotation or inversion on his error data but did show a less sensitively graded effect of rotation and the traditional inversion effect on reaction times. CR did not show a graded effect of rotation on his errors or reaction times. Although CR showed the traditional inversion effect on his error data, he displayed an inversion superiority effect on his reaction time data, which supports the claim that the damaged holistic processing systems continue to dominate face processing in prosopagnosia even though they are malfunctioning. These results suggest that the damage that occurs to the ventral temporal cortex in prosopagnosia may have forced the patients to rely on sources of information that are not dependent on the view of the face and, moreover, cannot be adapted to deal with rotated faces under both upright and inverted conditions.

Activation of brain areas related to face processing in prosopagnosia

Activation of brain areas related to face processing in prosopagnosia