Event Abstract Back to Event Understanding high-level visual discrimination by means of fast periodic oddball stimulation Joan Liu-Shuang1*, Anthony Norcia2 and Bruno Rossion1 1 University of Louvain, Belgium 2 Stanford University, United States The perceptual mechanisms underlying human observers’ ability to discriminate complex visual objects remain unresolved. This is especially true for faces, which human observers can efficiently individualise despite their high similarity. Previous studies have used classic adaptation paradigms to investigate the sensitivity of the visual system to face identity (i.e., 1; 2). In contrast to this approach, which measures sensitivity by comparing levels of adaptation between conditions containing same and different faces, here we propose a novel paradigm using fast periodic oddball stimulation that quantifies the discrimination response as an independent unit. We recorded 128-channel EEG in 20 observers presented with 60-second sequences of face stimuli shown at a constant frequency of 5.88 Hz. A “base face” (A) was repeated throughout each sequence with face size randomly varying at every cycle. Different faces (B, C, D…) were introduced at fixed intervals (every 4 stimuli, or 5.88 Hz/5 = 1.18 Hz), resulting in the following sequence structure: AAAABAAAAC... The presence of a response at 1.18 Hz is taken as an index of face discrimination, independently of the response at the main stimulation frequency of 5.88 Hz. To ensure that signal at 1.18 Hz truly reflected high-level face processing, we manipulated orientation (upright vs. inverted, Experiment 1) and contrast (normal contrast vs. contrast-reversed, Experiment 2). Both experiments showed significant increases of EEG amplitude at 1.18 Hz and its harmonics (2F = 2.35 Hz, 3F = 3.53 Hz…), with peak values in the right occipito-temporal channels. While the basic 5.88 Hz response was large for inverted and contrast-reversed faces, responses at 1.18 Hz and its harmonics – corresponding to face discrimination – were minimal in these conditions. Given these findings, the signal at the specific frequency of identity-change can be interpreted as an objective measure of face individualisation. In line with a recent study (3) highlighting the efficiency of periodic visual stimulation in investigating high-level visual processing, the current results underline the interest of the fast periodic oddball paradigm to explore fine-grained visual discrimination. References (1) Grill-Spector, K., & Malach, R. (2001). fMR-adaptation: a tool for studying the functional properties of human cortical neurons. Acta Psychologica, 107, 293–321. (2) Jacques, C., d’Arripe, O., & Rossion, B. (2007). The time course of the inversion effect during individual face discrimination. Journal of Vision, 7, 1–9. (3) Rossion, B., & Boremanse, A. (2011). Robust sensitivity to facial identity in the right human occipito-temporal cortex as revealed by steady-state visual-evoked potentials. Journal of Vision, 11, 1–21. Keywords: face processing, fast periodic stimulation, steady state visually evoked potentials (ssVEP), visual discrimination, EEG Conference: Belgian Brain Council, Liège, Belgium, 27 Oct - 27 Oct, 2012. Presentation Type: Poster Presentation Topic: Other basic/clinical neurosciences topic Citation: Liu-Shuang J, Norcia A and Rossion B (2012). Understanding high-level visual discrimination by means of fast periodic oddball stimulation. Conference Abstract: Belgian Brain Council. doi: 10.3389/conf.fnhum.2012.210.00005 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 07 Sep 2012; Published Online: 12 Sep 2012. * Correspondence: Ms. Joan Liu-Shuang, University of Louvain, Louvain-la-Neuve, Belgium, joan.liu@uclouvain.be Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Joan Liu-Shuang Anthony Norcia Bruno Rossion Google Joan Liu-Shuang Anthony Norcia Bruno Rossion Google Scholar Joan Liu-Shuang Anthony Norcia Bruno Rossion PubMed Joan Liu-Shuang Anthony Norcia Bruno Rossion Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.