Asymmetric bias in perception of facial affect among Roman and Arabic script readers.

The asymmetric chimeric faces test is used frequently as an indicator of right hemisphere involvement in the perception of facial affect, as the test is considered free of linguistic elements. Much of the original research with the asymmetric chimeric faces test was conducted with subjects reading left-to-right Roman script, i.e., English. As readers of right-to-left scripts, such as Arabic, demonstrated a mixed or weak rightward bias in judgements of facial affect, the influence of habitual scanning direction was thought to intersect with laterality. We administered the asymmetric chimeric faces test to 1239 adults who represented a range of script experience, i.e., Roman script readers (English and French), Arabic readers, bidirectional readers of Roman and Arabic scripts, and illiterates. Our findings supported the hypothesis that the bias in facial affect judgement is rooted in laterality, but can be influenced by script direction. Specifically, right-handed readers of Roman script demonstrated the greatest mean leftward score, and mixed-handed Arabic script readers demonstrated the greatest mean rightward score. Biliterates showed a gradual shift in asymmetric perception, as their scores fell between those of Roman and Arabic script readers, basically distributed in the order expected by their handedness and most often used script. Illiterates, whose only directional influence was laterality, showed a slight leftward bias.