Abstract
Purpose: In this study, we explored whether the selective processing of randomly moving objects is affected by unattended information in multiple object tracking (MOT). We examined the effect of the trajectories of distractors and the effect of global pattern, using priming paradigm.
Methods: Ten white circles ware presented and five of these circles were flashed, designating them as the target objects. Then all objects began to move independently in random directions. Thirty-nine observers asked to track five target objects for 5 s and indicate five targets with a mouse. Experimental trials were paired so that a “prime” trial was followed by a “test” trial. There were five experimental conditions. In positive-all condition, the trajectories of both target and distractor items in the prime trial were repeated in the test trial. In positive-target condition, only trajectories of target items were repeated, but those of distractor items were changed in the prime and the test trial. In negative-all condition, the trajectories of all items were repeated, but assignment of targets and distractors was reversed, so that both targets and distractors in the test trials were negatively primed. In negative-target condition, the trajectories of distractors in the prime trial were presented as targets in the test trial. Those of distractors in the test trial were reproduced. Therefore, only target items were primed in the test trial. In control condition, the trajectories of all items were changed between the test and the prime trial. The number of correctly tracked items was analyzed.
Results & Conclusion: We observed significant positive priming effect in positive-all condition. More importantly, there was negative priming effect in negative-all condition. No priming effect was observed in both positive-half and negative-half condition. These results suggest implicit encoding of target identities based on the global spatiotemporal information in MOT.