Normal acquisition of expertise with greebles in two cases of acquired prosopagnosia

Abstract

Face recognition is generally thought to rely on different neurocognitive mechanisms than most types of objects, but the specificity of these mechanisms is debated. One account suggests the mechanisms are specific to upright faces, whereas the expertise view proposes the mechanisms operate on objects of high withinclass similarity with which an observer has become proficient at rapid individuation. Much of the evidence cited in support of the expertise view comes from laboratory-based training experiments involving computer-generated objects called greebles that are designed to place face-like demands on recognition mechanisms. A fundamental prediction of the expertise hypothesis is that recognition deficits with faces will be accompanied by deficits with objects of expertise. Here we present two cases of acquired prosopagnosia, Herschel and Florence, who violate this prediction: Both show normal performance in a standard greeble training procedure, along with severe deficits on a matched face training procedure. Herschel and Florence also meet several response time criteria that advocates of the expertise view suggest signal successful acquisition of greeble expertise. Furthermore, Herschel's results show that greeble learning can occur without normal functioning of the right fusiform face area, an area proposed to mediate greeble expertise. The marked dissociation between face and greeble expertise undermines greeble-based claims challenging face-specificity and indicates face recognition mechanisms are not necessary for object recognition after laboratorybased training.

A Revised Neural Framework for Face Processing

“…These broad effects are consistent with accounts proposing that increased responses for objects of expertise result from increased attention (Harel et al 2010). Further evidence inconsistent with the expertise account comes from neuropsychological cases showing a dissociation between faces and objects of expertise (Sergent & Signoret 1992, Moscovitch et al 1997, Susilo et al 2013, Rezlescu et al 2014). More generally, the existence of brain areas that respond selectively to human bodies (Downing et al 2001), places (Epstein & Kanwisher 1998), and words (Cohen et al 2000, Baker et al 2007b, as well as that of other face-selective areas, raises the issue of why the expertise debate has focused solely on the FFA.…”

What is special about expertise? Visual expertise reveals the interactive nature of real-world object recognition

“…cars, birds, chess displays) were suggested to be processed by face network regions, particularly the Fusiform Face Area (Bilalić et al, 2011;Gauthier et al, 2000;Xu, 2005). Further, training studies with prosopagnosic patients reported pronounced difficulties in their ability to acquire a new type of visual expertise, in line with the idea that faces and objects of expertise share common perceptual and neural resources Bukach et al, 2012; but see Duchaine et al, 2004;Rezlescu et al, 2014).…”

Dynamic neural architecture for social knowledge retrieval

“…Eight distinct faces were generated by FaceGen Modeler 3.5, which allowed us to control low-level visual features such as color, brightness, and illumination. Eight artificial names were adapted from a previous study (69). The attractiveness and likeability of these artificial faces and names were carefully controlled by asking a different group of 20 participants to assign ratings.…”