Abstract:

The Multiple Object Tracking (MOT) task was initially designed by Pylyshyn and Storm (1988) and has been widely used to study the visual attentional mechanisms people use when viewing dynamic scenes. Previous research has usually used this task to explore participants’ abilities to track multiple moving objects in a static reference frame. But more recently, some researchers have started to investigate observers’ tracking performance in nonstable scenes. However, few studies have explored the effects of field dependent-independent cognitive style on tracking tasks from the point of view of individual differences. Previous research has revealed that field dependent-independent cognitive style affects people’s ways of perceiving and thinking. Field-independent individuals rely on an internal reference frame and tend to perceive objects separately from the background, while field-dependent individuals are more likely to rely on an external reference frame and perceive objects as a whole. We tested the effects of field dependent-independent cognitive style and abrupt rotation of the reference frame on tracking performance in the MOT task.
This study included two experiments. Experiment 1 compared performance differences between field- independent individuals and field-dependent individuals in the MOT task. Nineteen participants who scored ≥15 in the Embedded Figures Test (EFT) were classified as the extreme field-independent group, and twenty-three participants who scored ≤11 were classified as extreme field-dependent group. The two groups of participants were required to track 3, 4, or 5 targets in a static reference frame. Experiment 2 explored the tracking differences of the two groups in a nonstable reference frame with four targets. The procedure of Experiment 2 was the same as Experiment 1, except that after the motion of 6s in each trial, the reference frame abruptly changed 0°, 20°, or 40°. Meanwhile, the participants still needed to keep track of the targets.
The two experiments found significant differences between field-independent individuals and field-dependent individuals. In the low-difficulty conditions (stable reference frame, 3 and 4 targets) and the medium-difficulty condition (reference frame abruptly changed 20°, 4 targets), the field-independent group performed significantly better than the field-dependent group. But in the high-difficulty conditions (stable reference frame, 5 targets and reference frame abruptly changed 40°, 4 targets), the performance of the field-independent group did not significantly differ from the field-dependent group. The results revealed that the tracking differences between the two groups of participants were influenced by task difficulty. In addition, participants’ tracking accuracy significantly decreased along with increases in the number of targets and the abrupt rotation of the reference frame. We speculate that the increased cognitive load and discontinuous scene made it more difficult for participants to track the targets, which contributed to the significant decline of tracking accuracy.
In general, by using the MOT task and changing the motion reference frame, we explored the different performances of field dependent-independent individuals in the classic MOT task and an MOT task with a changing reference frame. This study offers an explanation for the different characteristic of field dependent- independent cognitive style from the perspective of multiple object tracking. In addition, changing the MOT to include rotation of the reference frame allows us to study tracking in a situation that is similar to shifts of perspective in the real world, which provides some evidence for how people deploy attention while processing in dynamic scenes.

Key words: multiple object tracking, field dependence-independence, reference frame, scene rotation