A simple example of having your reading interrupted by a fire alarm illustrates a fundamental aspect of attention - what ultimately reaches our awareness and guides our behaviour depends on the interaction between goal-directed and stimulus-driven attention. For coherent behaviour to emerge, you need these two forms of attention to be coordinated, say the scientists. Now they have found a brain area, the inferior frontal junction, that may play a primary role in coordinating these two forms of attention.
The researchers were also interested in what happens to us when our attention is captured by an unexpected event, and they found that when shown a surprise stimulus, we are temporarily blinded to subsequent events.
In their study, the research team asked individuals to detect the letter "X" in a stream of letters appearing on a screen while their brain activity was being monitored using functional magnetic resonance imaging, or fMRI. Occasionally, an image of a face would unexpectedly interrupt the stream. The surprise caused the subject to completely miss the "X" the first couple of times, despite the fact they were staring directly at the part of the screen on which it appeared. They were eventually able to identify it as successfully as when there was no surprise. Later, using fMRI, the researchers found that the inferior frontal junction, a region of the lateral prefrontal cortex, was involved in both the original task and in the reaction to the surprise.
Scientists say that what might be happening is that this brain area is coordinating different attention systems - it has a response both when you are controlling your attention and when you feel as though your attention is jerked away.
Surprise stimuli trigger what is known as the orienting response in which the heart rate increases, the nervous system is more aroused and we pay intense attention to a new item in our environment. The orienting response allows one to determine if a new item is a good thing, such as food, or a threat, such as a predator, and to react accordingly.
The researchers hypothesize that we may be temporarily blinded by surprise because the surprise stimulus and subsequent response occupies so much of our processing ability. The idea is that we can't attend to everything at once and it seems that the inferior frontal junction is involved in this limitation in attention.
The new research supports previous work that found the interior frontal junction plays the role of an attentional bottleneck - limiting our ability to multitask and attend to many things at once.
These new findings in addition to the previous findings suggest that this area is centrally involved in the control of attention and may limit our attentional capacities, say the researchers; and it is a very exciting convergence of findings across our studies. They're still conducting studies to demonstrate whether in fact disruption of activity in this brain region leads to loss of control of attention.
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