Evidence for Asymmetrical Hemispheric Priming Using Known and Unknown Warning Stimuli in Two Language-Trained Chimpanzees (Pan troglodytes)

In this article results are reported from 3 warning stimulus-printing experiments that assessed hemisphere-specific activation and lateralization in 2 language-trained chimpanzees (Pan troglodytes). Results from Experiment 1 indicated a right visual field advantage in priming for meaningful warning stimuli presented in blocks of 36 trials. In Experiments 2 and 3, randomized presentations of meaningful, familiar, and meaningless stimuli resulted in right visual field advantages for meaningful warning stimuli. No visual half-field differences were found for familiar or meaningless warning stimuli. The findings are similar to those found in human subjects using known-unknown symbol paradigms; they suggest that basic phylogenetic neuropsychological systems related to activation and priming processes may link nonhuman primate and human studies of lateralization.