Memory effects of motor activation in subject-performed tasks and sign language.

Research on memory has consistently shown that when a subject-performed task (SPT) is compared with a traditional verbal task (VT), enactment at the encoding of verbal materials (i.e., SPT) yields better memory performance than does nonenactment (i.e. VT). There is some controversy regarding the extent to which motor activation per se might be causing this effect, and whether or not SPTs may be influenced by memory strategies. The purpose of this study was to contribute toward a solution of these questions. The effect of SPT encoding was compared with the effect of encoding by means of a sign language task (SLT). The SLT condition is claimed to be a verbal/linguistic task with a major relevant motor component. The motor activation in SLT is in the present study seen to be the main difference between the SLT and the VT, and the main similarity between the SLT and the SPT. Control conditions were tested in order to evaluate possible effects of translation and imagery in the SLT condition. Subjects in the SLT condition performed similarly to subjects in the SPT condition in free recall. Subjects in both these conditions outperformed subjects in the control conditions. The SPT and SLT superiority is suggested to be caused mainly by relevant motor activation.