The timecourse of expert and novice visual object encoding

Face processing experiences a temporal advantage relative to that of other categories; electrophysiological responses in categorization tasks suggest that processing begins 25ms earlier for faces than objects (e.g., Caldara et al., 2003). This advantage appears to be specific to upright faces (Rossion et al., 2000). It has been argued that identity-level representations are available for faces and objects of expertise earlier than for other categories (Tanaka & Taylor, 1991; Tanaka, 2001), although this claim has been challenged (Grill-Spector & Kanwisher, 2005). Here, we attempt to measure more precisely a possible temporal advantage for encoding upright, relative to inverted, faces, in the context of identification judgments. We also investigate the same question with non-face objects of expertise. Experiment 1 compared the timecourse of upright and inverted unfamiliar face processing using a backward masking identity-matching paradigm with a range of stimulus-mask onset asynchronies (12ms–1000ms). Matching performance for upright faces rose above chance at around 40ms, approximately 70ms earlier than that for inverted faces. Experiment 2 compared the processing timecourse for car identity matching among car experts and novices. Notably, car experts' performance demonstrated an initial ‘head-start’ of approximately 40ms over novices' performance, also rising above chance at around 40ms. Our results are consistent with faster access to the subordinate-level by experts observed in studies with coarser temporal resolution (e.g.,Tanaka, 2001). This early advantage could reflect a difference in processing strategies (e.g., holistic vs. part-based) or the benefits of the automatic weighing of diagnostic features for very familiar categories.