Unilateral vibrotactile stimulation induces emotional biases in cognition and performance.

We administered 24 min of unilateral vibrotactile stimulation to the left or right ventral forearm of experimental participants. A separate control group did not receive stimulation but completed all experimental tasks. Participants who received right-side stimulation persisted more in attempting to solve insoluble puzzles and also made more positive judgments about an emotionally neutral film compared to participants who received left-side stimulation. The performance of the control group was intermediate to that of the stimulation groups, but was significantly different only from the right stimulation group. The absence of a significant left-side stimulation effect is not readily interpretable because floor effects may have limited the attenuating effects of left-side stimulation on persistence in problem solving. Emotional biases in cognition and performance resulting from unilateral vibrotactile stimulation can be explained with reference to activation of structures involved in the processing of emotion within the contralateral cerebral hemisphere, and by the laterality of emotion specified in the Valence Hypothesis. These results support the contention that similar biases elicited by unilateral muscle contractions result from their sensory consequences.