Study finds conscious perception occurs outside the visual system

A recent study has found that the conscious perception (global neural networks) of visual location occurs in the frontal lobes of the brain, rather than in the visual system in the back of the brain.

The findings are published in Current Biology.

According to Sirui Liu, a graduate student of psychological and brain sciences at Dartmouth, "Our study provides clear evidence that the visual system is not representing what we see but is representing the physical world."

"What we see emerges later in the processing hierarchy, in the frontal areas of the brain that are not usually associated with visual processing," said the lead author.

To examine how the perception of position occurs in the brain, participants were presented with visual stimuli and asked to complete a series of behavioural tasks while in a functional magnetic resonance imaging (fMRI) scanner.

For one of the tasks, participants were asked to stare at a fixed black dot on the left side of the computer screen inside the scanner while a dot that flickered between black and white, known as a Gabor patch, moved in the periphery. Participants were asked to identify the direction the patch was moving.

The researchers found that while the visual system collects the data, the switch between coding the physical path and coding the perceived path (illusory path) takes place outside of the visual cortex all the way in the frontal areas, which are higher-order brain regions.

According to Patrick Cavanagh, a research professor of psychological and brain sciences at Dartmouth, "Our data firmly support that frontal areas are critical to the emergence of conscious perception."

While previous research has long established the frontal lobes are responsible for functions such as decision-making and thinking, our findings suggest that this area of the brain is also the end step for perceiving where objects are. So, that's kind of radical," he added.