Labelling memory set sizes in older and younger adults

In previous visual and memory search (hybrid search) experiments, we have found that older adults (OA) are slower and less accurate than younger adults (YA) to reject distractors that belong to the same basic category as the targets. Distractors of the target category should evoke “category-related” noise that should remain distinct enough from targets’ signal to be quickly rejected. It may be possible that OA do not rely on this distinction and engage in an exhaustive memory search to reject distractors. OA may recollect the entire target set just to confirm that the distractor does not belong to the targets, resulting in a process akin to a recollection-to-reject, resulting in a longer (and sometimes ineffective) memory search. In this experiment younger and older observers will learn 2 sets of items (8 items per set) that belong to the same basic category (e.g. cats). We have chosen a memory load of 8 items as in our previous work we have described the memory costs from switching from learning 2 items to 8 items in both YA and OA. Each set will be associated with a specific label (e.g., “These cats were seen in Auckland” vs “These cats were seen in Wellington”). After ensuring memorization and good discrimination between both sets, participants will be shown a visual array of 4 items and asked to report if a member of a specific set (e.g., a cat from Wellington) is present. The distractors items will include cats from the other memorized set (cats from Auckland), as well as novel items from the same basic category (non-label cats), and distractors of a similar (e.g. dogs) or different basic category (e.g. beds). In addition, we will use a control condition with four different distractors to ensure our participants engage in the task. By assigning distinct labels to the target set and one distractor set, we aim to provide a recollection-based cue that may facilitate rejection of labeled distractors, particularly in older adults who may otherwise rely on a less efficient exhaustive memory search. Simultaneously, including a non-labeled distractor set will allow us to isolate the contribution of familiarity signals to distractor rejection. With this design we aim to dissociate the differential contributions of recollection and familiarity-based processes in younger and older adults in hybrid search.