The left side of gestures: left perceptual bias for meaningless hand gestures recognition is independent from handedness

The "Left Perceptual Bias" (LPB) is the effect for which the left side of a picture such as a face is used to a greater extent than its right side as shown in a wide variety of experimental tasks. This effect has been observed for faces, body parts and objects. The present work investigated the presence of a LPB in recognizing hand gestures in two experiments. The role of the side of stimuli presentation (left /right), stimuli orientation (palm/back), participants' handedness and gender were analyzed. Participants were presented with images of meaningless gestures performed by an actor with the right or left hand, from a palm or a back view. Immediately afterward, participants were shown a drawing and had to discriminate whether it represented the same gesture or not. In the first experiment, the task was administered to a sample of right-handed participants, half males. Results showed shorter response times for stimuli presented on the left side and for those shown from the palm. No gender differences were observed. The second experiment included a sample of left-handed participants and the LPB was replicated. Taken together, our results suggest an interpretation of the bias in terms of asymmetries in perceptual processing rather than the involvement of motor representations.