Skin potential response in letter recognition task as an alternative communication channel for individuals with severe motor disability

Objectives: Skin potential responses (SPRs) to target and non-target stimuli in letter recognition tasks were studied to evaluate their potential as communication channels for individuals with severe motor disability. Methods: SPRs were recorded from the palm or sole of 5 subjects with cerebral palsy and 6 healthy subjects. Subjects discriminated target letters from non-target ones in a random sequence of single letters. In Task 1, subjects made a behavioral response upon presentation of the target. In Task 2, the target letters were presented as ‘go’ or ‘nogo’ signals. Results: For target letters, irrespective of behavioral requirements (‘go’ or ‘nogo’), skin potential waves frequently occurred with latency consistent with the sympathetic skin response (SSR) latency, and were regarded as SPRs evoked by target stimuli. In Task 1, the occurrence rate of the SPR was 47% for target, and 4% for non-target stimuli. In Task 2, the SPR occurred in 34% of ‘go’ target, 29% of ‘nogo’ target, and 2% of non-target stimuli. Conclusions: SPRs with SSR latency are potentially useful in controlling signals of communication tools for individuals with severe motor disability.