Abstract
Evidence suggests that the perception of facial appearance is driven more by one side of the face than the other. A left-side bias for face perception has been shown using a chimeric face matching task, in which observers tend to judge a face composed of the two left halves of a face (the side of the face in the left visual field of the observer, here termed the LL face), to more closely resemble the original face than the RR face. This effect is thought to arise from right hemisphere specialization for faces. Here, we examined the effect of reading direction on this facial bias in a large group of subjects proficient either in English, Arabic (read from right to left) or both languages. Observers performed the chimeric face matching task whilst their eye movements were measured, and an additional group of observers performed the task online. To evaluate whether the bias was specific to the side of the face in the left visual field or the physical half of the face, the target face was presented as originally photographed and as its mirror-reversed version (on separate trials). The results confirm a left-side bias for face perception, both in choice responses and in eye movements, consistent with previous work. The bias was modulated by language proficiency: observers more proficient in Arabic than in English showed a smaller bias, which was reversed in sign in certain conditions, and their eye movements were more symmetrically distributed across the target face than English-reading observers. Unexpectedly, the bias was smaller for the mirror-reversed target faces than the original faces for all groups. We interpret the results overall as an effect of visual experience, here, habitual scanning of text, on a putatively hard-wired perceptual bias.