The workload implications of haptic displays in multi-display environments such as the cockpit: Dual-task interference of within-sense haptic inputs (tactile/proprioceptive) and between-sense inputs (tactile/proprioceptive/auditory/visual)

Visual workload demand within the cockpit is reaching saturation, whereas the haptic sense (proprioceptive and tactile sensation) is relatively untapped, despite studies suggesting the benefits of haptic displays. MRT suggests that inputs from haptic displays will not interfere with inputs from visual or auditory displays. MRT is based on the premise that multisensory integration occurs only after unisensory processing. However, recent neuroscientific findings suggest that the distinction between unisensory versus multisensory processing is much more blurred than previously thought. This programme of work had the following two research objectives:

1. To examine whether multiple haptic inputs can be processed at the same time without performance decrement

Study One 2. To examine whether haptic inputs can be processed at the same time as visual or auditory inputs without performance decrement

Study Two In Study One participants performed dual-tasks, consisting of same-sense tasks (tactile or proprioceptive) or different-sense tasks (tactile and proprioceptive). These tasks also varied in terms of processing code, in line with MRT. The results found significantly more performance decrement for the same-sense dual-tasks than for the different-sense dual-tasks, in accordance with MRT, suggesting that performance will suffer if two haptic displays of the same type are used concurrently. An adjustment to the MRT model is suggested to incorporate these results. In Study Two, participants performed different-sense dual-tasks, consisting of auditory or visual tasks with tactile or proprioceptive tasks. The tasks also varied in terms of processing code. Contrary to MRT, the results found that when processing code was different, there was significant performance decrement for all of the dual-tasks, but not when processing code was the same. These results reveal an exception to two key MRT rules, the sensory resource rule and the processing code rule. It is suggested that MRT may be oversimplistic and other factors highlighted by recent neuroscientific research should be taken into account in theories of dual-task performance.