Poster D121, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Lower visual field advantage as a default setting for processing facial and non-facial stimuli : evidence from a combined EEG and Eye-tracking study.
Sandra Guerreiro Jacinto1,2, Edwige Taniga1, Anthony Hosein1, Boutheina Jemel1,2; 1Hôpital Rivière des Prairies, 2Université de Montréal
Several studies have consistently shown that the human visual perception displays a low visual field (LVF) advantage, with stimuli presented in LVF being processed more efficiently than those in the higher VF (HVF). In addition, photoreceptors’ distribution is denser in the upper half of the retina. Face research literature has outlined that the most relevant information is located in the upper part of the face (eyes), which triggers the largest brain electrical signal known as the face-sensitive N170 ERP. Furthermore, Zerouali et al. (2013) showed that fixating the top of a face stimulus elicits the highest N170 amplitude, whether the face is presented upright or inverted, suggesting that the observed upper-fixation bias is independent of the eye-region location but is rather a consequence of LVF advantage. To follow up on this conclusion, EEG and eye-tracking measurements were recorded and monitored simultaneously to allow an accurate sampling of electrical brain signals from fixated image regions, while participants viewed face photographs, face-like phase-scrambled images and face-like checkerboards. ERPs were averaged by gaze location (upper, mid and lower). Our results revealed a similar pattern between the three types of stimuli. We observed an optimal fixation position (i.e., eliciting the largest N170s) located on the upper-visual field, with N170 decreasing amplitude from the upper to the lower fixations. Such results suggest that N170 amplitude modulations arise from a general retinotopic visual setting enhancing visual information located in the LVF of facial and non-facial stimuli.
Topic Area: PERCEPTION & ACTION: Vision