You look familiar, but I don’t care: Lure rejection in hybrid visual and memory search is not based on familiarity

In “hybrid” search tasks, observers hold multiple possible targets in memory while searching for those targets amongst distractor items in visual displays. Wolfe (2012) found that, if the target set is held constant over a block of trials, RTs in such tasks were a linear function of the number of items in the visual display and a linear function of the log of the number of items held in memory. However, in such tasks, the targets can become far more familiar than the distractors. Does this “familiarity” – operationalized here as the frequency and recency with which an item has appeared – influence performance in hybrid tasks In Experiment 1, we compared searches where distractors appeared with the same frequency as the targets to searches where all distractors were novel. Distractor familiarity did not have any reliable effect on search. In Experiment 2, most distractors were novel but some critical distractors were as common as the targets while others were 4× more common. Familiar distractors did not produce false alarm errors, though they did slightly increase response times (RTs). In Experiment 3, observers successfully searched for the new, unfamiliar item among distractors that, in many cases, had been seen only once before. We conclude that when the memory set is held constant for many trials, item familiarity alone does not cause observers to mistakenly confuse target with distractors.