A unified bottleneck in our brains limits our attention

It has been a common assumption that different tasks requiring our attention, like making perception distinctions or making action choices are limited by brain areas most associated with those function. Tombu et al. now find a unified attentional bottleneck, including the inferior frontal junction, superior medial frontal cortex, and bilateral insula.

Human information processing is characterized by bottlenecks that constrain throughput. These bottlenecks limit both what we can perceive and what we can act on in multitask settings. Although perceptual and response limitations are often attributed to independent information processing bottlenecks, it has recently been suggested that a common attentional limitation may be responsible for both. To date, however, evidence supporting the existence of such a “unified” bottleneck has been mixed. Here, we tested the unified bottleneck hypothesis using time-resolved fMRI. The first experiment isolated brain regions involved in the response selection bottleneck that limits speeded dual-task performance. These same brain regions were not only engaged by a perceptual encoding task in a second experiment, their activity also tracked delays to a speeded decision-making task caused by concurrent perceptual encoding in a third experiment. We conclude that a unified attentional bottleneck, including the inferior frontal junction, superior medial frontal cortex, and bilateral insula, temporally limits operations as diverse as perceptual encoding and decision-making.