Normal and abnormal category-effects in visual object recognition: A legacy of Glyn W. Humphreys

Abstract

ABSTRACTAre all categories of objects recognized in the same manner visually? Evidence from neuropsychology suggests they are not, as some brain injured patients are more impaired in recognizing natural objects than artefacts while others show the opposite impairment. In an attempt to explain category-specific deficits for natural objects Glyn Humphreys and colleagues suggested that natural objects are harder to perceptually differentiate than artefacts because natural objects are more structurally similar than artefacts. This explanation was proposed in the context of the Cascade model of visual object naming. While this model has been successful in accounting for a number of observations concerning category-specificity in both patients with brain injury and normal subjects, it has also become clear that there are many important aspects of category-specificity that the model cannot accommodate. These limitations have led to the development of a new model of category-effects at pre-semantic stages in visual object processing, which can be considered a further development of the Cascade model: the Pre-semantic Account of Category-Effects (PACE). Here I give a slightly historical, but primarily integrative, account of this development including recent studies which address important aspects of both the Cascade and the PACE models.