One face or two? Contrasting different versions of the chimeric faces test.

The chimeric faces test is a frequently used behavioural test of lateralisation; however the methodologies used vary considerably. In this experiment the one- and two-face versions of the test, using neutral/happy chimeras, were compared to see whether the laterality biases found are correlated. Both versions showed a significant left visual field (or half face) bias, indicating that both reflect the underlying right hemisphere superiority for processing positive facial emotion. Furthermore, the laterality bias was significantly correlated in both versions although reliability was higher for the two-face version.