Mirror-image matching and mental rotation problem solving by baboons (Papio papio): unilateral input enhances performance.

Three experiments, using a matching-to-sample procedure, were conducted to examine hemispheric specialization in mirror-image discrimination and mental rotation in baboons (Papio papio). In Experiment 1, no significant difference was found in discrimination of mirror-image and asymmetric pattern stimuli. In Experiment 2, orientation discrimination was assessed within the left (LVF) and right (RVF) visual half-fields. An RVF advantage was found in accuracy for asymmetric patterns, whereas an LVF advantage was found for discrimination of mirror-image stimuli. No significant relation was found between angular disparity of the stimuli and response time. Experiment 3 examined the effect of bilateral visual input on accuracy and response time. Significantly lower accuracy and longer response times were found for bilateral compared with unilateral visual input.