Abstract
At VSS09, we presented experiments in which participants saw an initial face for 3500 ms, a brief probe face (120 ms), and made same/different identity judgments. Inversion of the left eye in probes (initially projected to the right hemiphere) resulted in lengthened same judgment RTs compared to when probes were unaltered, while inversion of the right eye (initially projected to the left hemisphere) did not result in lengthened RTs relative to unaltered conditions. We took these results to show RH sensitivity to manipulations of face configuration. The present experiments used this same technique. First we created a set of highly standardized faces (identical face shape and eyebrow “frames,” with internal features swapped to create identities). We made 5 pixel movements of each eye alone and each eye plus eyebrow to the outside of the face (horizontal) and downward (vertical) to uncover potential differential hemispheric sensitivity to horizontal and vertical displacements. We reduced initial face duration to 400 ms. Movements of eye plus eyebrow were more disruptive to same judgment RTs than movements of the eye alone, and horizontal movements were more disruptive than vertical movements. Unlike our previous work, effects of the side of manipulation were weak. We found some evidence that the LH was more negatively affected by eye plus eyebrow movements than eye alone movements but the RH was not. Horizontal movements of the eye plus brow were more disruptive than eye alone horizontal movements, but there was no difference in same judgment RTs for vertical eye plus brow and eye alone vertical movements. In another experiment we lengthened the initial display to investigate “memorial” vs. “perceptual” contributions to hemispheric effects. We relate our results to inversion effect studies revealing a configurational anisotropy of horizontal and vertical displacements of facial features (Goffaux and Rossion, 2007).