Abstract
Although human adults can learn to individualize novel 3D multiparts objects, there is little evidence that their visual representations are modified following learning. To address this issue, we developed 3D objects where the global structure, parts and their configuration, as well as the texture can be parametrically manipulated to create large sets of stimuli with individual variations. Importantly, parts are configured so that stimuli appear as “face-like” in one orientation. We trained two groups of 11 subjects to become experts at individuating 26 novel object exemplars, either in face-like or non-face-like orientation. Importantly, non-face-like oriented stimuli were not perceived as faces. Training consisted of 14 sessions (~20 hrs) during two weeks, where novel objects were seen from different viewpoints in a variety of tasks. Pre and post training, we measured electrophysiological discrimination responses using a fast oddball periodic visual stimulation providing robust and objective (i.e. at a predefined frequency) visual discrimination responses (1Liu-Shuang et al., 2014). In each of only 4 trials per condition, an identical object picture (unseen at training) was presented at 6 Hz for 60 seconds, and different individual objects appeared at regular intervals (1/5, i.e. at 1.2 Hz). Following training, a discrimination response at 1.2 Hz and its harmonics (e.g., 2.4 Hz, etc.) over lateral occipital sites increased significantly for face-like configurations. Strikingly, despite equivalent amount of training for both configurations, there was no such increase of the EEG visual discrimination response for non-face-like configurations. These results indicate that visual representations of novel objects are modified following training, and suggest that a face-like configuration is essential to observe these effects. 1Liu-Shuang, J., Norcia, A.M., Rossion, B. (2014). An objective index of individual face discrimination in the right occipito-temporal cortex by means of fast periodic oddball stimulation. Neuropsychologia, 52, 57-72.
Meeting abstract presented at VSS 2015