Skill and hemispheric specialization in detecting featural differences in visual images.

Visual asymmetry patterns related to skill were examined during a target-probe matching task in 24 skilled medical technologists and 24 matched controls. On each of 240 test trials, digitized replicas of specimens commonly encountered in medical laboratory diagnostics were shown centrally for 500 msec. Each target was immediately followed by a lateralized probe item for 120 msec that was either an exact copy (positive probe) or a distorted version (negative probe) of the target. Difficulty level of target-probe matching was manipulated on negative probe trials; half of the negative items consisted of difficult discriminations which were selected to assess the effects of domain-specific experience on detecting small differences in salient morphological features. Medical technologists exhibited a right visual field advantage, but were not different from the control subjects in speed or accuracy to positive probes or to easy negative probes. The observed left-hemisphere advantage in skilled visual processing is attributed to the beneficial effects of experience on the development of domain-specific visual analysis skills.