Abstract
Previous research has found that inhibition-of-return (IOR) is a task-specific strategy, where participants are significantly slower to return to previously fixated locations in a search task compared to in a non-search task, where facilitation-of-return (FOR) is observed (Dodd et al., 2009). In these contexts, IOR and FOR reflect a differential influence of memory on attention as a function of task demands. Moreover, task set influences the spatial and temporal characteristics of eye movements, such as the rate of change in fixation duration (Mills et al., 2011). In these tasks, search is generally participant-directed, meaning participants have no expectation regarding where the target will appear and can search however they choose. Many real world search tasks, however, are constrained by top-down knowledge regarding a target's expected location, which can be replicated in the laboratory via experimenter-directed search (participants receive explicit direction where to search).. The purpose of the current study was to examine the influence of task set (search, memorize, evaluate) and search type (experimenter-directed vs. participant-directed) on oculomotor behavior. Participants were presented with a series of scenes that pictured common real-world environments (e.g., kitchens) and either a) searched for an embedded N or Z, b) memorized the scene, or c) rated the pleasantness of the scene. Task type could be blocked or mixed and participants were either provided with specific direction as to where targets were likely to appear or were told the target could appear anywhere. Critically, whereas participant-directed search yielded IOR, experimenter-directed search yielded FOR in both mixed and blocked conditions. The rate of change and magnitude of fixation durations was also impacted by search instruction. These results demonstrate an important dissociation between the facilitatory and inhibitory effects of memory on attention and eye movements as a function of search type.
Meeting abstract presented at VSS 2014