TY - JOUR

T1 - Visual crowding in pure alexia and acquired prosopagnosia

AU - Sand, Katrine

AU - Robotham, Ro Julia

AU - Martelli, Marialuisa

AU - Starrfelt, Randi

PY - 2018/10/3

Y1 - 2018/10/3

N2 - Visual crowding is a phenomenon that impairs object recognition when the features of an object are positioned too closely together. Crowding limits recognition in normal peripheral vision and it has been suggested to be the core deficit in visual agnosia, leading to a domain-general deficit in object recognition. Using a recently developed tool, we test whether crowding is the underlying deficit in four patients with category specific agnosias: Two with pure alexia and two with acquired prosopagnosia. We expected all patients to show abnormal crowding. We find that the two patients with acquired prosopagnosia show abnormal crowding effects in foveal vision, while the pure alexic patients do not, and that this constitutes a significant dissociation. Thus, abnormal crowding cannot explain all cases of visual agnosia. Much recent work has focused on similarities between pure alexia and acquired prosopagnosia. Here we show a difference in a basic visual mechanism—visual crowding.

AB - Visual crowding is a phenomenon that impairs object recognition when the features of an object are positioned too closely together. Crowding limits recognition in normal peripheral vision and it has been suggested to be the core deficit in visual agnosia, leading to a domain-general deficit in object recognition. Using a recently developed tool, we test whether crowding is the underlying deficit in four patients with category specific agnosias: Two with pure alexia and two with acquired prosopagnosia. We expected all patients to show abnormal crowding. We find that the two patients with acquired prosopagnosia show abnormal crowding effects in foveal vision, while the pure alexic patients do not, and that this constitutes a significant dissociation. Thus, abnormal crowding cannot explain all cases of visual agnosia. Much recent work has focused on similarities between pure alexia and acquired prosopagnosia. Here we show a difference in a basic visual mechanism—visual crowding.

KW - acquired prosopagnosia

KW - Crowding

KW - pure alexia

KW - visual agnosia

U2 - 10.1080/02643294.2018.1483325

DO - 10.1080/02643294.2018.1483325

M3 - Journal article

C2 - 29902952

AN - SCOPUS:85053899957

VL - 35

SP - 361

EP - 370

JO - Cognitive Neuropsychology

JF - Cognitive Neuropsychology

SN - 0264-3294

IS - 7

ER -