Tracking while counting

The multiple object tracking task introduced by Pylyshyn more than 30 years ago has changed our understanding of attention and its functions. In one study George Alvarez and I found that subjects could manage two simultaneous tracking tasks with little cost if they were in separate, left and right hemifields. This challenged the idea that attention was a central, monolithic resource suggesting that it might be something more peripheral that could be split up (Alvarez & Cavanagh, 2005 PDF). George then came up with a demonstration in defense of the centrality of the attention required for tracking. Below is a standard tracking task, Three disks will flash orange to indicate which targets to track. Keep following them with attention until the end when they again turn orange so you can see how well you did.

Fine, that is the baseline. Now to test how much this task overlaps with central processes, repeat the same tracking task — just run the video again — but now while counting out loud backwards by 3s from 97. The counting task is not visual and yet you may find that your performance suffers.

Well, it might if you are unilingual. In her honors thesis at Glendon in 2018, Ana Janic, supervised by Josée Rivest, ran this tracking and counting task on 35 monolinguals and 36 bilinguals (with some speaking 3 or more languages). The results showed that the baseline tracking performance was the same for monolinguals and bilinguals but once the counting was added, monolingual tracking performance dropped dramatically and significantly more than for bilinguals. So being bilingual helps you multitask. You can download a pdf of the VSS 2019 poster by clicking

Multiple Object Tracking
The three orange flashing disks you see after it starts are your targets. Follow them. How well did you do?
Then repeat the trial while counting backwards, out loud, by 3s, from 97.