Face identity matching is selectively impaired in developmental prosopagnosia

Abstract

Individuals with developmental prosopagnosia (DP) have severe face recognition deficits, but the mechanisms that are responsible for these deficits have not yet been fully identified. We assessed whether the activation of visual working memory for individual faces is selectively impaired in DP. Twelve DPs and twelve age-matched control participants were tested in a task where they reported whether successively presented faces showed the same or two different individuals, and another task where they judged whether the faces showed the same or different facial expressions. Repetitions versus changes of the other currently irrelevant attribute were varied independently. DPs showed impaired performance in the identity task, but performed at the same level as controls in the expression task. An electrophysiological marker for the activation of visual face memory by identity matches (N250r component) was strongly attenuated in the DP group, and the size of this attenuation was correlated with poor performance in a standardized face recognition test. Results demonstrate an identity-specific deficit of visual face memory in DPs. Their reduced sensitivity to identity matches in the presence of other image changes could result from earlier deficits in the perceptual extraction of image-invariant visual identity cues from face images.

Holistic face perception is impaired in developmental prosopagnosia

“…In contrast to a previous study (Fisher et al, 2017), N250r amplitudes on full face repetition trials were not correlated with CFMT performance in the DP group (see also Wirth, Fisher, Towler, & Eimer, 2015, for a link between N250r components and CFMT scores in unimpaired participants). This difference may simply reflect variability between different relatively small samples of DPs.…”

“…Confirming previous observations (Fisher et al, 2017), we found substantial differences between individual DPs in the size of their N250r amplitudes to full face repetitions versus changes, with some DPs showing reliable N250r components in the normal range ( Figure 5, top panel). A similar pattern was also found for the superadditivity of N250r components for full versus partial feature repetitions ( Figure 5, bottom panel).…”

“…The analysis of N250r components to full face repetitions in the DP group confirmed previous observations (Fisher et al, 2017) that DPs have significant but strongly reduced N250r components as compared to age-matched control participants without face processing impairments. Individuals with DP showed reliable N250r components not only in response to full face repetitions versus changes, but also to partial repetitions of both internal and external features.…”

“…Previous research has shown that individuals with DP have disproportionate difficulties in face identity matching when the sample and test images visually vary more substantially (for example, the same person posing different facial expressions as compared to a similar expression; e.g. Fisher et al, 2017;White, Rivolta, Burton, Al-Janabi, & Palermo, 2017). This suggests that face recognition deficits in DP arise at the stage of forming image-invariant face identity representations.…”

“…Based on this distribution, the reliability of an empirically observed ERP difference between conditions was determined for individual participants. If the probability of obtaining the observed difference by chance is below 5%, it is accepted as statistically significant (see Dalrymple et al, 2011;Oruc et al, 2011;Fisher et al, 2016Fisher et al, , 2017, for previous applications of this procedure in ERP studies of prosopagnosia). In the present experiment, this bootstrap procedure was based on EEG mean amplitudes obtained between 230 and 280 ms after S2 onset on full repetition and full change trials (collapsed the eight lateral posterior electrodes over the left and right hemisphere).…”