Chimeric faces, visual field bias, and reaction time bias: have we been missing a trick?

The chimeric faces test is a frequently used behavioural test of lateralisation for cognitive processing. Performance on this task is typically quantified in terms of bias towards selecting faces where positive facial emotion is expressed in the viewer's left visual field, indicating right hemisphere dominance for the task. This paper examines an alternative measure that may be extracted from responses to the chimeric faces test: reaction time bias. There was a strong positive correlation between the two asymmetry measures, which remained even after controlling for sex and handedness. The possible uses of reaction time bias in the measurement of cerebral lateralisation are discussed.