Handedness and the mental rotation of perceived patterns

The present experiment investigated the effect of hemispheric dominance, as indicated by handedness, and perceptual processing. Displays containing two visual patterns were presented to right- and left-handed subjects who classified the two patterns as being the same or different. Also the two patterns in a display were in either an identical orientation or nonidentical orientations. Overall, left handers were faster than right handers at the "same-different" judgement. Additionally, latency increased with the angular discrepancy in orientation between patterns for both handedness groups but this increase was smaller for left handers than for right handers. Apparently, left handers evaluate overall perceptual similarity faster than right handers and they also mentally rotate perceived patterns of discrepant orientations faster than right handers. These findings contradict previous generalizations that left handers are deficient perceptually. Moreover, the present results support the position that left handers should be faster at global perceptual tasks because left handers have less neural distance than right handers mediating the transmission of information between the locus of perception and the locus of dominance.