Abstract:

Multiple Object Tracking (MOT) developed by Pylyshyn and Storm (1988) has been widely used in the study of capacity-limited and object-based attention. Many researchers interested in finding out whether or not the tracking processes in MOT occupy attentional resource and what type of resource is used. The typical paradigm used in this line of research is dual-task paradigm. Participants were asked to perform a visual or auditory task and the MOT task simultaneously. MOT performance was interfered by both the visual and the auditory task. However, the interference of visual task and auditory task with MOT occurred at different levels. The previous studies demonstrated that the MOT task and visual task occupy visual attention resources. Although the MOT task and auditory task don’t occupy visual attention resources, they share more central attention resources (such as executive function). Multiple Identity Tracking (MIT) is a variant of MOT, in which each object carries a unique identity. The previous studies also included both visual or auditory task and MIT task, but those studies have not examined how the visual/auditory task affects the MIT task when the two tasks shared the same properties. The current study included 3 experiments and aimed to investigate the influence of a visual or auditory task on either MOT or MIT task. The first two experiments manipulated participants’ eye movement to compare the different effects of visual task and auditory task on MOT performance. The result of experiment 1A showed that the auditory task interfered more with MOT than did the visual task when eyes were fixated at the center of the screen. However, the auditory task yielded less interference with MOT when there was no eye movement control in experiment 1B. The results indicated that the tracking processes in MOT not only occupy visual attention resources, but also occupy central attention resources (such as executive function). The experiment 2 applied visual and auditory digit judgment task and MIT task. When the object identity (marked by a digit) was identical to the number in the digit judgment, the MIT performance was facilitated by both the visual and auditory task. It is possible that the process of digit activated the target identities (the same digits) that was stored in visual working memory during tracking.

Key words: Multiple Object Tracking, dual-task, visual attention resources, central attention resources