Left versus right hand differences in exploratory strategies: facts and relevance to the development of haptic devices

Lacreuse, A., Fagot, J. & Vauclair, J. (1996). Hand differences in haptic exploratory strategies : Facts and implications for the development of haptic devices. ASME, 58, 567-573

 

 

Abstract – The literature provides conflicting results with regards to hand/hemisphere lateralization in haptic perception; while some papers report a left hand advantage for recognizing haptic forms, other studies indicate either a right hand advantage or no hand difference at all. Four experiments with right handed subjects will be presented, in which scanning strategies and performance were investigated when subjects touched nonsense forms by either the left or right hand. The research involved a novel apparatus and composite stimuli made of cubes whose junctions were not haptically discernible. During the inspection of the shape, the location and duration of any hand contact with the cubes comprising the stimulus were recorded, allowing thus an analysis of exploratory strategies. The first experiment implied the inspection of a target stimulus with either the left or right hand. Thereafter, subjects were requested to identify the drawing of the target stimulus displayed among different drawings. No hand differences were obtained in terms of scores. It was found, however, that in men the left hand touched the stimuli more globally than the right. In the second experiment, subjects were requested to inspect in simultaneity two forms with two hands (i.e., dichhaptic task), before recognizing the forms on the visual array. Here, the left hand outperformed the right hand. Moreover, as in the previous experiment, the left hand touched the shape more globally than the right. Results also demonstrated that only 20% of the total exploration time was devoted to a simultaneous inspection of the two forms. The two additional experiments focused on hand performance and exploratory strategies for recognizing the stimuli, instead of learning them. No hand differences were observed in strategy, whatever the mode of exploration (either dichhaptic or monohaptic). By contrast, recognition achieved by the left hand was better than that of the right hand, but this effect was restricted to dichhaptic recognition only. Overall, we conclude that this series of experiments demonstrates the reality of hand/hemispheric differences in the processing of haptic information by men. We argue, moreover, that these findings are of particular relevance for the development and use of haptic devices that are designed to display haptic information on body segments (e.g., tactile or force feedback devices). Firstly, they suggest a serious consideration of the laterality factor for stimulating subjects, in order to enhance pattern recognition. Secondly, they suggest that information presented to the left hand would be more easily processed if it was displayed globally, whereas information presented to the right hand would be more easily and efficiently processed when made available in a sequential manner. Finally, the results show a limited capacity to process two distinct sources of haptic information at the same time.