Helping Hands : Motion and integration in action memory

Verbal information has predominantly been the to-be-remembered materials in human memory research for more than a century. In recent years some interesting deviations from the established rules of verbal memory have been observed in subjects who have been asked to motorically self-perform (enact) action sentences at the encoding phase of the memory task, instead of only hearing or reading them as in a traditional verbal task (VT). Marked enhancements in recall were also consistently demonstrated in such studies and the effect was named the subject-performed task (SPT) effect. Presently, the body of SPT research is large but little agreement has been reached regarding the mechanism at work in producing the SPT phenomenon. The present thesis addresses two major issues in SPT research. The enhancement of associative information and the significance of the motor component are evaluated. In Study A, the SPT effect was studied in two cued-recall tasks that relied on item-specific association and relational association, respectively. The results showed that SPT encoding interacts with item-specific associative cues at recall to produce a larger SPT effect as compared to free recall. This supports the notion that part of the SPT effect is due to enhanced item-specific association. In Study B, the associative effect in SPT was studied amongst age cohorts comprised of subjects between 40 and 85 years old. Normal age-related decline in episodic memory has elsewhere been suggested to be caused mainly by associative deficits connected with ageing. The results of Study B indicate that the item-specific associative effect in SPT was more age sensitive than recall of VT and the relational associative effect in SPT. In Study C, the question over whether the SPT effect is dependent on motor modality or not was addressed. Self-produced sign language encoding was argued to be qualitatively the same as self-produced oral/verbal encoding, with the motor modality component being the only exception. It was also argued that the motor modality component was the main similarity to performing SPT. Since the signing subjects performed at the same level as the SPT condition at recall, and better than the control conditions (e.g., VT), the conclusion was made that motor activation per se can contribute to memory enhancement in SPT. Whether SPT encoding results in qualitatively different memory traces is discussed as well as the effect of SPT on other types of associative information. The results are also briefly related to other controversies in SPT research. It is concluded, finally, that enactment produces differential effects on different types of associations. The association between verb and noun is clearly enhanced by SPT encoding. Moreover, it is concluded that overt motor activation is necessary for obtaining a full SPT effect. To explore these interactions further and to build upon these conclusions, an increased focus on motor processes and their relation to verbal processes is called for in future cognitive research