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At any given moment, humans are bombarded with a constant stream of new information. But the brain can take in only a fraction of that information at once. So how does the brain decide what to pay attention to and what to ignore? Many laboratory studies of attention avoid this issue by simply telling participants what to attend to. But in daily life, people rarely receive instructions like that. Instead people must often rely on past experiences to guide their attention. When cycling close to home, for example, a person knows to watch out for the blind junction at the top of the hill and for the large pothole just around the corner.
Günseli and Aly set out to bridge the gap between laboratory studies of attention and real-world experience by asking healthy volunteers to perform two versions of a task while lying inside a brain scanner. The task involved looking at pictures of rooms with different shapes. Each room also contained a different painting. In one version of the task, the volunteers were told to pay attention to either the paintings or to the room shapes. In the other version, the volunteers had to use previously memorized cues to work out for themselves whether they should focus on the paintings or on the shapes.
The brain scans showed that two areas of the brain with roles in memory – the hippocampus and the prefrontal cortex – were involved in the task. Notably, both areas increased their activity when the volunteers used memory to guide their attention, compared to when they received instructions telling them what to focus on. Moreover, patterns of activity within the hippocampus and prefrontal cortex contained information about what the participants were about to focus on next – even before volunteers saw the particular picture that they were supposed to pay attention to. In the hippocampus, this was particularly the case when the volunteers based their decisions on memory.
These results reveal a key way in which humans leverage memories of past experiences to help optimize future behavior. Understanding this process could shed light on why memory impairments make it harder for people to adjust their behavior to achieve specific goals.