Abstract
Asymmetries between left and right as well as upper and lower visual hemifield were investigated using a visual detection task with face stimuli. Participants had to detect a face with a gaze direction different from the remaining faces. Gaze was either direct (looking straight ahead) or indirect (looking sideways). The gaze singleton was either a direct gaze among faces with indirect gaze or an indirect gaze among faces with direct gaze. Participants were faster to respond when targets were presented in the upper left quadrant of the visual field compared to the other quadrants. This finding is in line with the literature. As participants have to process faces we expected them to use holistic processing, which is known to be better in the right hemisphere and should therefore lead to an advantage in the left hemifield. The upper visual field advantage was also expected because high-level processing such as object recognition or face processing is better in the upper visual field (Quek & Finkbeiner, 2015). Further, the left hemifield advantage disappeared when the same face stimuli were presented upside-down which confirms that the laterality effect is related to holistic processing of faces rather than to low-level stimulus characteristics. Additionally, the advantage of the upper visual field disappeared when the visual search task was made easier by presenting nontargets with closed eyes. In sum, our findings show that both laterality and elevation affect reaction times in search for a face singleton.
Meeting abstract presented at VSS 2016