| Prospective memory (PM) is a concept with respect to retrospective memory, and refers to the processes associated with remembering to perform an intended action at some time in the future. According to the different stimuli cues, two types of PM have been distinguished: event-based PM and time-based PM. The present investigation focused on the latter one. A key procedural feature of all PM paradigms is that they require the self-initiated execution of the intended action when the cues turn out, while being engaged in an ongoing activity, which is considered by the participants as the main task. Empirically, this requirement is paralleled in the laboratory by involving participants in an attentionally demanding task in which the PM events are embedded as apparently normal ongoing task items. While, by now, this requirement is acknowledged as a standard feature of PM paradigms across all areas of PM research, surprisingly, one major aspect of the general empirical procedure varies across paradigms applied: whether or not the participant has to refrain from dealing with the ongoing activity coincidently with the PM event and immediately switch to the prospective action. In other words, some PM paradigms are instructed as dual-task procedures: here, the participant has to work on both tasks simultaneously. In contrast, other PM paradigms are instructed as task-switch procedures: here, the participant has to immediately stop working on the ongoing task as soon as they encounter a PM cue and directly perform the prospective action. Interestingly, in reviewing the literature, many studies either do not clearly specify the route they took in the methods descriptions or explicitly leave it to the participant to decide how to perform the task.For investigating whether working memory load affects the execution of event-based PM and what the effect is in both dual-task and task-switch procedures, three experiments were carried out.Experiment 1 was designed as a one-factorial study with the between-subject factor of task version (ongoing task only, dual-task and task-switch), aiming to indicate whether there was interference effect of inhibition when participants were acquired to accomplish the task-switch procedure, relative to the dual-task procedure.Experiment 2 was a two-factorial study design with the factors of task version (dual-task and task-switch, between-subject) and working memory load (WM load=0,1,3, within- subject), so as to figure out whether the cause of interference effect changed, as WM load moved on.To sum up, two cognitive processes have been involved, which are ongoing activity and prospective activity, and one conclusion has been figured out: it is increasing WM load that enhanced the occupation of cognitive resource. What would have happened, however, if WM load of PM was raised? To answer this question, experiment 3 was implemented, which was a two-factorial study design with the factors of the number of cues (1 or 3, between- subject) and working memory load of ongoing task (WM load=1or3, between-subject).The conclusion is: 1) when the WM load of ongoing activity is low, there is interference effect of inhibition in task-switch, which results in delay of reaction time in task-switch procedure, relative to that in dual-task procedure; 2) when the WM load of ongoing activity is high, the mentioned inhibition is weakened relatively, meanwhile, the lack of cognitive recourse is highlighted by the high load, which primarily cause the delay; 3) a negative effect is observed both when the WM load of ongoing task is enhanced and so do the WM load of PM, nevertheless, the latter effect is not outstanding; 4) consistent with bi-process theory, both automatic and strategic process are involved in the process of intention retrieval, and which one is adopted lies on the working memory load of not only ongoing activity but prospective activity.
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