Masking and visual field effects on a lateralized rod-and-frame test.

The rod-and-frame test (RFT) has been widely used in the study of sex differences in spatial abilities. However, laterality studies involving this test are very scarce. An experiment was conducted to investigate whether laterality effects would be affected by post-stimulus masking. Ninety-six subjects participated in the experiment. For half the subjects, stimuli were followed by a blank screen, while for the other half, stimuli were followed by a mask. An overall left visual field advantage (LVFA) was found in the task. An interaction of sex of subjects, masking conditions, and frame tilt was also found. Further analyses showed that the sex by angle of frame interaction was significant when a mask was presented after the stimuli, but not when no mask followed the stimuli. Data tended to confirm the hypothesis that the LVFA was only significant when a mask was presented after the stimuli. These findings demonstrate the usefulness of a masking procedure in visual field studies, whereas the right hemisphere advantage found on the RFT is consistent with previous findings with visuo-spatial tasks.