Behavioural lateralization of tactile performance in the rat.

Ten rats were assessed for behavioural lateralization using two different tests: paw preference and tail-suspension test. It was found that animals, at an individual level, tended to have a behavioural preference which was polarized either to the left side or the right side. Animals were then randomly assigned to two groups. One group had whiskers trimmed ipsilateral, and the other group had whisker trimmed contralateral, to their lateralized behavioural preference. Over 10 days the rats were trained on a roughness discrimination task. It was found that animals with whiskers trimmed on the contralateral side performed better (p<.05) than those with whiskers trimmed on the ipsilateral side. This finding was associated with a large effect size (partial eta(2)) of .474. The side of whisker trimming (right versus left) per se had no effect on performance (p=.26). These results indicate that motor lateralization at the individual level is associated with lateralization in the efficacy of whisker use.