Fig 1.
An example of a typical Multiple Object Tracking (MOT) task.
The targets to be tracked are indicated during the cue phase, e.g., by flashing red for 1.5 seconds. The cues disappear and all objects begin moving independently during the tracking phase for a limited time, e.g., 6 seconds. Finally, during the response phase, the observer is prompted to indicate the location of the targets. In this example one object is probed and a ‘yes’ or ‘no’ response would be made. The square boundaries are shown only for illustrative purposes; the stimuli are usually bounded by the screen dimensions.
Fig 2.
A diagram of the stimuli used in all Experiments.
A) In Experiment 1a the memory array of the visual working memory (VWM) task was displayed first, followed by a brief blank period before the multiple object tracking (MOT) task began. The MOT cue phase began with the discs stationary for 1 second, and then moving for 2 seconds. The tracking phase proceeded for 5 seconds, followed by the MOT probe phase, and finally the response phase. On 50% of trials the MOT response would be requested, and on the other 50% of trials the VWM response would be requested. B) In Experiment 1b the full array of stimuli was displayed during the VWM response phase, not the single probe item that was displayed in Experiment 1a. C) In Experiment 2 both the MOT and VWM components of the display were presented concurrently throughout the trial.
Fig 3.
Experiment 1a: Individual and group performance.
Mean accuracy in each condition for the multiple object tracking (MOT) task shown in the top panel, and for the visual working memory (VWM) task in the bottom panel. Group analysis, to the far right in each panel, is consistent with previous research, however individual performance shows substantial variation, particularly in the MOT task. Error bars represent 95% confidence intervals.
Table 1.
Repeated measures ANOVA comparing of MOT performance between conditions for each observer.
Table 2.
Repeated measures ANOVA comparing of VWM performance between conditions for each observer.
Fig 4.
Experiment 1b: Individual and group performance when both tasks were calibrated separately for each individual.
Mean accuracy in each condition for the multiple object tracking (MOT) task shown in the top panel, and for the visual working memory (VWM) task in the bottom panel. Group analysis to the far right in each panel. Error bars represent 95% confidence intervals.
Table 3.
Repeated measures ANOVA comparing of VWM performance between conditions for each observer.
Fig 5.
Experiment 2: Mean accuracy in each condition.
Single-task and dual-task performance for each observer for the multiple object tracking (MOT) and visual working memory (VWM) tasks. Group analysis to the far right. Error bars represent 95% confidence intervals.
Table 4.
Comparison of single- and dual-task performance for MOT and VWM tasks for each observer.