Abstract
Purpose: Numerous studies reported that observer could track 4 or 5 moving targets among identical moving distractors. Pylyshyn (1988) proposed the existence of individuating indexes that were assigned to tracked objects. While Yantis (1992) claimed that the importance of grouping processes for tracked objects. We showed that the processing of distractors in multiple object tracking (MOT) was also important, using contextual cueing procedure (Chun & Jiang, 1998). Method: Ten white circles were presented and five of these circles were flashed, designating them as the target objects. Then all objects began to move independently in random directions. Seventeen naïve observers were asked to track five moving target objects for 5 s and indicate the five targets using the mouse after the tracking. The two main variables were spatio-temporal pattern (Consistent vs Distractor-Variable vs All-Variable) and epoch (1–5). The Consistent set of motion pattern consisted of 5 randomly generated patterns in which the trajectories of the all objects were consistent through the experiment, presented once per block. The Distractor-Variable (DV) set consisted of 5 different patterns which only the target trajectory were repeated. The All-Variable (AV) set consisted of 5 different patterns that were newly generated for each block. Each pattern for Consistent and DV was repeated 15 times through the entire experiment. After MOT session, observers asked to perform the recognition task for consistent motion pattern. Result: The MOT performance showed significant contextual cueing effect, which was greater for consistent patterns than DV patterns. Besides the performance in the recognition task did not show any significant difference from chance level. Conclusion: The spatio-temporal information of distractors served as the implicit contextual information and facilitated tracking performance. This suggests the importance of the information that was not explicitly processed during MOT.
This research was supported by Grants of the MEXT and the NEDO.