On Prospective memory (PM) and interruption/distraction

• abstract: age-related PM decrements often dramatic when retrieval was facile; when initial retrieval difficult, older adults showed no forgetting over retention interval

• intro: researchers have found reliable and even substantial age differences in retrieve-execute type of PM task (REPM)
• one variable that seems to affect magnitude of age differences on PM task is demands of background task (BT); resource demands of BT can sig. affect PM, especially for older adults
• age-related deficits in remembering to perform an action could be due to older adults having fewer resources available for the PM task and not to an inherent deficit in retrieving PMs
• when retrieval cue is salient, an automatic retrieval process is stimulated that obligatorily delivers intended action to consciousness
• unclear what to expect when one has to delay execution of intention after retrieval (retrieve-delay PM task / RDPM)
• purpose of present research to examine RDPM performance
• reasonable to propose that reformulating a plan while performing an ongoing task and strategically maintaining an intention would be heavily dependent on working-memory resources
• consistent evidence that increasing working-memory demands of BT decreases PM performance, especially for older adults; relation b/w WM and PM - very little evidence for an association between the two;

• experiment 1: created a delay of 30-39s b/w occurrence of PM target and when it was appropriate to perform intended action; also measured WM capacity; varied presence or absence of secondary digit-detection task;
• highly salient targets used; given possible similarities and differences b/w REPM and RDPM, we could anticipate absence or presence of age-related deficits
• to equate conditions, needed to present the older adults with less material and at a slower rate;
• design was 2 (age) x 2 (delay/no delay) x 2 (attentional demands, WS); reading 3-sentence paragraphs, followed by reading-comprehension questions, two trivia questions; had interest in ability to remember to perform future actions; if they encountered a target word on any of the 3 sentences, they were to immediately press the F1 key (REPM), or to delay until the trivia phase (RDPM); those in divided attention condition given digit-monitoring task, see [Einstein 97];
• 20 paragraphs presented either w/ or w/o digit monitoring task, counterbalanced in each exp. condition, first prospective target appeared in 3rd paragraph, PM targets not presented in consecutive paragraphs; target words always appeared in 2nd sentence of a paragraphs; following this, subjects given vocab. test and WM memory span test;
• results: introducing a delay significantly lowered PM performance in no-delay and delay conditions; in no-delay condition, main effect of age was marginally significant; PM performance not affected by divided attention, no interaction b/w age and divided attention; highly salient target -> near perfect performance in no-delay condition regardless of age and divided attention;
• in delay condition, main effect of age: younger participants had higher PM than older participants, PM performance sig. worse in divide attention, decrement more pronounced for older adults (but no interaction); highly salient targets for REPM to not depend on availability of attentional resources, RDPM tasks poses special difficulties for older adults;
• smaller working memory spans for older adults; WM resources related to maintaining a PM intention over delay interval; WM likely a major factor in mediating relation b/w age and PM; analyses suggest age-related effect in PM primarily associated w/ WM processes;
• other measures: dividing attention interfered w/ comprehension, younger adults had higher scores than older adults, older adults more difficulty w/ digit monitoring

• experiment 2: important purpose of second experiment was to examine reliability of this rapid loss of PM and age-related differences after a delay; under these conditions, maintaining intended action in working memory after retrieval would be more critical for successful PM;
• varied demands of delay activity and length of delay (10, 30s) - delays were filled/unfilled w/ synonym questions;
• older adults do not have working memory resources needed to actively maintain intention through rehearsal over retention interval while simultaneously performing BT; performance on RDPM should be affected by demands of BT, during unfilled delays all participants should be affected by demands of the activities occurring during the delay; during unfilled delays all participants should be able to focus their WM resources on task of maintaining intention, performance should be high for older adults and younger adults;
• [Hasher and Zack 88,94]: ageing disrupts efficient functioning of inhibitory processes, perhaps more distractible, difficulty inhibiting thoughts unrelated to the cognitive demands of maintaining an intention until it is performed; older adults may show large amounts of forgetting even with unfilled delays;
• pilot work indicated that older adults had great difficulty reading items, generating answers, circling answer within allotted time; called out answers instead to experimenter
• 2 (young/old) x 2 (delay, WS) x 2 (filled/unfilled delay, WS) mixed factorial design; delay was synonym task or break for 10 or 30 s; target always occurred in last sentence of paragraph, thus delays b/w offset of sentence containing target and occurrence of target phase were wither 10 or 30s; each participant received 5 short-unfilled, 5 short-filled, 5 long-unfilled, and 5 long-filled delay periods, 4 counterbalanced orderings, equal # of participants assigned to each delay order;
• given WM operation span test afterwards to establish more general support for relation b/w WM and performance on RDPM tasks;