Active touch does not improve sequential processing in a counting task

Abstract

Active touch involves tactile and proprioceptive sensory inputs, activation of the motor system and executive functions. It has been shown by the previous literature that active touch facilitates shape recognition. Since both active and passive exploration requires sequential presentation of the tactile inputs, this facilitation may be due to the improvement of the sequentialprocessing mechanism. The effects of active and passive touch on the sequential processing of tactile inputs were tested at different stimuluspresentation rates in a counting task. Active touch did not improve the performance, which shows that the additional sensory and motor information conveyed by active exploration are not utilized by the sequential-processing mechanism. Therefore, the results cannot be explained by the feature-specific theory of sequential processing. On the other hand, the counting errors were higher than those predicted by the limitation of the minimal inter-stimulus interval, which is suggested by the central-timing theory. Consequently, it is proposed that a mechanism based on the central-timing theory may contribute to tactile sequential processing, but the bottleneck at high presentation rates is probably due to short-term memory. Correspondence should be addressed to B. Güçlü, Email: burak.guclu@boun.edu.tr