Changes in immediate memory strategy under induced muscle tension and with time of day

It is suggested that the influence of arousal on immediate memory may, at least in part, be mediated by changes in strategy, such that subjects are less likely to rely on cumulative subvocal rehearsal of the items under high arousal. Experiment I found a detrimental effect of induced muscle tension on immediate memory, but only when subjects were free to engage in such rehearsal, and not under either enforced vocalisation or articulatory suppression. Experiment II manipulated strategy by instruction, and compared immediate memory at 10.30 (low arousal) with that at 19.30 (high arousal). A 10.30 superiority in immediate memory was found when no specific instructions as to how to either encode/store, or recall, the items were given. This superiority disappeared under four of the five alternative types of instruction where subjects were told to group and rehearse the items during presentation, or to recall the items in a specific order, or both. It is concluded that manipulations commonly held to affect arousal level may indeed influence the type of strategy that subjects spontaneously adopt. This may be responsible for some of the inconsistencies in the arousal and memory literature.