Just as how watching a pile of notes "pop up" dollar signs in Uncle Scrooge's, a comic book character, eyes, thinking about money lights up visual areas of human brains too, Say's the report of a new research.
Led by John Serences, assistant professor of psychology and head of the Perception and Cognition Lab at UC San Diego, the study is published in the Dec. 26 issue of the Cell Press journal Neuron.
Past rewards influence how humans (and other animals) make decisions. We've known about that for a long time, said Serences - through day-to-day experience as well as the numerous experiments of economists and cognitive psychologists.
Though more and more research is looking into it, little is known about how rewards affect the way the brain processes incoming sensory information, specifically as it relates to vision.
Serences examined how value affects visual processing with functional magnetic resonance imaging (fMRI), a brain-scanning technique that indirectly measures neural activity.
The brain activity of subjects was recorded as they chose between red and green targets that varied in value across the experiment. Selecting a target might yield 10 cents or nothing, potentially earning subjects making the "right" choices 10 dollars.
Analysis revealed that rewards altered neural activation in many areas of the human visual system, including the very first visually responsive region of the brain, the area of the cortex known as "V1," which is associated with representing basic features such as edge orientations and color.
"When a target had been valuable in the past - if selecting it had paid off with money- the visual system represented it more strongly," Serences said.
"Rewards affected information processing not just at a high level of cognitive function but right from the get-go."
"Though it is too early to say how this relates to perception," said Serences, "it raises the intriguing possibility that we see things we value more clearly - much like the way the brain responds to a bright object versus a dimly lit one."
Interestingly, changes in neural activity were better associated with the reward history of the red/green targets than with self-reported estimates of value: "It's as if the visual system is telling you how valuable something has been to you in the past," Serences said, "and telling it to you like it is, even though you can't consciously identify it."
The study also found activation in the frontal and parietal regions of the brain previously implicated in anticipating and tracking rewards. These areas were very active when one choice was much more valuable than the other, suggesting, Serences said, that these regions may provide signals to bias visual processing and so have a greater impact on decision-making and behavior.