Disposed to distraction: genetic variation in the cholinergic system influences distractibility but not time-on-task effects

Abstract

Both the passage of time and external distraction make it difficult to keep attention on the task at hand. We tested the hypothesis that time-on-task and external distraction pose independent challenges to attention and that the brain's cholinergic system selectively modulates our ability to resist distraction. Participants with a polymorphism limiting cholinergic capacity (Ile89Val variant [rs1013940] of the choline transporter gene SLC5A7) and matched controls completed self-report measures of attention and a laboratory task that measured decrements in sustained attention with and without distraction. We found evidence that distraction and time-on-task effects are independent and that the cholinergic system is strongly linked to greater vulnerability to distraction. Ile89Val participants reported more distraction during everyday life than controls, and their task performance was more severely impacted by the presence of an ecologically valid video distractor (similar to a television playing in the background). These results are the first to demonstrate a specific impairment in cognitive control associated with the Ile89Val polymorphism and add to behavioral and cognitive neuroscience studies indicating the cholinergic system's critical role in overcoming distraction.

Figure 1. CTET with video distractor

As shown in (a) each trial consisted of a black and white grid made up of squares divided into triangles. At the end of the trial, the triangles rotated (90,180, or 270 degrees, chosen randomly) to start the next trial. The participant’s task was to press the spacebar when they realized that the grid had taken longer than usual (1070 ms rather than the standard 800 ms) to rotate. (b) The distractor manipulation was implemented using a laptop oriented 32° to the left of the main task computer. In the No Distractor condition, the laptop was silent and displayed a gray screen. In the Distractor condition, it played video clips with sound.

Figure 2. CTET performance with and without video distractor

Markers represent mean proportion of hits for each minute; error bars represent standard error of the mean. Both groups exhibit time-on-task and distraction effects that do not interact, and the distractor effect is larger for IIeVal89 participants.

Figure 3. Correlations between distractor-related performance declines in the CTET, self-rated “trait” distractibility measured using the PAC, self-rated “state” distractibility measured using the post-task questionnaire, and performance on the post-task quiz for memory of the content of the distracting videos

Larger numbers indicate greater distractibility. If the data from the control subject in the lower left corner are excluded, the correlations remain in the same direction as indicated in the main text at reduced effect size (r = .20 for trait distraction, r = .22 for state distraction, and r = .29 for distractor memory).