The capacity and cognitive processing of vibrotactile working memory for frequency

A hallmark of working memory (WM) is its limited capacity. While visual and verbal domains of WM are able to store multiple items, the capacity of parametric vibrotactile WM (vtWM) has not yet been established for supra-threshold, one-dimensional sensory vibrotactile frequencies. The present study extends the standard delayed match-to-sample vibrotactile discrimination task to determine the capacity of the vtWM and its cognitive mechanism. Here, by presenting subjects with 2 to 6 vibratory frequencies sequentially in each trial, the present study demonstrates that it is possible to retain about only two vibrotactile frequencies information in vtWM. The results also showed that the capacity of vtWM does not depend on whether sequentially presented vibrotactile frequencies are delivered to the same or to different fingers. At the same time, the rate of correct report depends on sequence length and when in the sequence the stimuli are presented, suggesting the dynamic updating of vtWM similar to that of visual WM.