Abstract
In hybrid search tasks, observers search the environment for multiple target items they hold in memory (e.g., locating ingredients for a recipe in the supermarket). Previous research showed that search performance deteriorates with the number of targets memorized (Wolfe, 2012). The current studies tested how the familiarity and activation level of memory items affect hybrid search efficiency. In the first two experiments, we contrasted performance for a set of 16 search targets seen once with a set where memory strength was increased by repeating items 8x (Exp. 1) or by repeating and asking questions about the items (e.g., “What is the primary use for this object?”) to encourage deeper processing (Exp. 2). In a third experiment we selected participants based on their self-reported expertise in sports to capitalize on their strong memories for certain sport logos (NFL vs. NHL fans). We then compared search for 16 targets in their domain of expertise with 12 targets from the other sport. In all experiments, after the memorization and memory test phases, participants performed a visual search at small or large set sizes (6 vs 12 or 8 vs 16). Search performance was measured using inverse efficiency scores (IES) to account for speed/accuracy tradeoffs. Across all experiments (overall N=143), IES scores were generally lower for the high strength memory condition than the low strength memory condition. This indicates better search performance for target sets with stronger memory representations, even when the stronger memory list was larger. Broadly, these data contrast with the idea of a simple search through lists of items in memory. They show that differences in memory strength — and therefore differences in how accessible items are — can account for key aspects of memory set size effects in hybrid search.