The Scanpaths of Subjects with Developmental Prosopagnosia during a Face Memory Task

Abstract

The scanpaths of healthy subjects show biases towards the upper face, the eyes and the center of the face, which suggests that their fixations are guided by a feature hierarchy towards the regions most informative for face identification. However, subjects with developmental prosopagnosia have a lifelong impairment in face processing. Whether this is reflected in the loss of normal face-scanning strategies is not known. The goal of this study was to determine if subjects with developmental prosopagnosia showed anomalous scanning biases as they processed the identity of faces. We recorded the fixations of 10 subjects with developmental prosopagnosia as they performed a face memorization and recognition task, for comparison with 8 subjects with acquired prosopagnosia (four with anterior temporal lesions and four with occipitotemporal lesions) and 20 control subjects. The scanning of healthy subjects confirmed a bias to fixate the upper over the lower face, the eyes over the mouth, and the central over the peripheral face. Subjects with acquired prosopagnosia from occipitotemporal lesions had more dispersed fixations and a trend to fixate less informative facial regions. Subjects with developmental prosopagnosia did not differ from the controls. At a single-subject level, some developmental subjects performed abnormally, but none consistently across all metrics. Scanning distributions were not related to scores on perceptual or memory tests for faces. We conclude that despite lifelong difficulty with faces, subjects with developmental prosopagnosia still have an internal facial schema that guides their scanning behavior.

Search for Face Identity or Expression: Set Size Effects in Developmental Prosopagnosia

“…This led the authors to speculate that prosopagnosia may be characterized by both impaired face perception from damage to the right fusiform face network, as well as inability to attend to facial regions useful for identification, such as the eyes, which may be mediated by the left frontal network. Indeed, other studies of acquired prosopagnosia have found a failure to process eye information, particularly under attentionally demanding conditions (Pancaroglu et al, 2016;Caldara et al, 2005), whereas some but not all studies of developmental prosopagnosia have shown reduced scanning of the eyes (Lee, Corrow, Pancaroglu, & Barton, 2019;Bobak, Parris, Gregory, Bennetts, & Bate, 2017).…”

Face Feature Change Detection Ability in Developmental Prosopagnosia and Super-Recognisers

“…This was also found in another study examining the ability of DPs and controls to detect changes in “critical” features and “non-critical” features, where DPs showed similar patterns of response to controls [ 32 ]. One study which used eye tracking to measure scan paths during a face memory task showed no difference in scan paths of faces in DPs and controls, with both groups showing a bias towards the eyes over the mouth [ 52 ] (for different findings, see [ 31 ]). Taken together with our results, this suggests that DPs may be impaired in detecting changes to all internal facial features rather than having a specific or pronounced deficit for the eye region.…”

Facing the Best in Handling Prosopagnosia

“…Remedial strategies aim to train more general skills that can be applied to any face, with the idea to facilitate more effective "normal" processing strategies. Typically, these techniques are used in patients with prosopagnosia due to impaired non-perceptual mechanisms that would be difficult to achieve otherwise (Young & Ellis, 1989) games or tasks to establish correct face scanning paths (Lee et al, 2019). Internal feature training focuses on the ability to distinguish different facial features, such as lip shape, eye colour, or distances between facial features, such as the spacing between the eyes and brows or the nose and mouth (DeGutis et al, 2007;Ding & Martinez, 2010).…”