关键词: 真实场景搜索, 视空工作记忆, 目标模板, 视觉混乱度, 眼动

Abstract:

Many theories of attention have proposed that visuo-spatial working memory plays an important role in visual search. Previous studies have examined the involvement of visuo-spatial working memory in visual search using dual-task paradigm in which participants performed a visual search task concurrently with either a spatial working memory task or an object working memory task. It has been found that the presence of spatial working memory load adds a delay to the concurrent visual search reaction times and impairs the efficiency of a concurrent visual search task. In addition, the object working memory load prolongs the concurrent visual search reaction times and impairs the efficiency of a concurrent visual search task only when the target identity varies constantly from trial to trial. The present article extended traditional visual search to real-world scene search and investigated how the spatial and object working memory affected the real-world scene search performance (search reaction time, accuracy and search efficiency) by employing dual task paradigm. Meanwhile, the mediations of target template specification and visual clutter of search scene picture on these effect were considered. In the present study, 96 participants’ eye movement were monitored using an EyeLink 1000 when they were performing a single task or dual tasks. In the single task, participants searched for a specific target object cued by an abstract cue (a word) or a specific cue (an exact matching picture of the target); in the dual tasks, they performed a real-world scene search task during the delay interval of a visual working memory task (remember four color squares or four spatial locations). The four-factor mixed design was employed, with memory loads (non-load, object load and spatial load) and target type (change and constant) being the between-subjects variables, and visual clutter (high vs. low) and target template (word cue: a word identifying the target vs. picture cue: an exactly matching picture of the target) being the within-subject variables. The main findings were as follows: (1) Compared to the non-load condition, adding a spatial load slowed the search reaction times and decreased search accuracy and adding an object load only decreased accuracy of search. Adding an object load delayed the durations of scanning epoch when the target was cued by picture of it and adding spatial load prolonged the durations of scanning epoch and verification epoch and increased the fixation number during scanning epoch, mediated by specification of target template. (2) Compared to the non-load condition, adding a spatial load decreased scene search efficiency and this effect was mediated by visual clutter of the scene picture. However, the object load did not influence the scene search efficiency. These findings suggest that the effects of spatial working memory and object working memory on the real-world scene search were not same as their effects on the traditional visual search. The spatial working memory load can affect the reaction time, search accuracy and scanning epoch and verification epoch and the object working memory load can affect the search accuracy and scaning epoch and these effects was mediated by specification of target template. The effect of spatial memory load on the scene search efficiency was mediated by visual clutter of the scene picture.

Key words: visuo-spatial working memory, visual search, target template, visual clutter, eye movement