A lateral masking effect in tactile and blurred visual letter recognition

In a letter recognition task in which the letters were presented temporally across two columns of a vibrotactile array, the masking effects of added columns of steady vibrotactile stimulation were investigated. The primary variable studied was the spatial separation between the masking columns and the letter-carrying columns. The results indicate a spatially dependent masking effect which is independent of the tactile masking associated with mask onset. A comparable masking effect was obtained with visual letter recognition using the same relative stimulus configurations viewed under conditions of optical blurring. An interpretation of the tactile masking is offered in terms of the limited spatial resolution of the cutaneous sense.