Decision-making Debunked

December 2013

What guides the decisions we make? Past research indicates that our choices, both voluntary and involuntary, are separate processes in the brain. But, according to a study by Sarah Shomstein and recently published in Psychological Science, the processes are linked and decisions are ultimately made based on the perception of a reward.

“Think about when you’re at the supermarket, picking out fruit,” said Shomstein, an associate professor of cognitive neuroscience in Columbian College’s Department of Psychology. “You will most likely refrain from picking out a mango if you got food poisoning after eating a mango salad the week before; however, you will not hesitate to choose a fruit that has not led to any recent discomfort.”

Through her research, Shomstein found that in making choices, such as which fruit to buy, there are two types of interwoven processes at work. For example, in the scenario outlined above, the active avoidance of mangos unfolds by way of voluntary attentional control, but other fruit selections may be guided by involuntary attention and influenced by physical properties of the fruits, such as bright colors, shapes, or accessibility.

“When viewing the world around us, our perceptual system is bombarded by a large amount of sensory information that our brains simply cannot process all at once,” said Shomstein. “To understand the environment, the brain’s perceptual system has to select a subset of information for further processing. The critical question is how the brain chooses what to process first.”

In her study—funded by the National Science Foundation and the National Institutes of Health, and co-authored by Jacoba Johnson, a clinical psychology graduate student at Bryn Mawr —Shomstein developed several experiments to determine factors that influenced choice. To test whether a reward-based choice is a separate cognitive process from an involuntary or attentional choice, she presented identical visual stimuli to observers and manipulated what targets or objects were rewarded and the type of reward—money or points—were received. She found that reward, not the objects, guided attentional selection and predicted behavior.

The results led to two important conclusions, which are in stark contrast to previous research: Not all attentional selection is automatic and involuntary; and some involuntary behaviors are fully determined by reward.

“While reward is the primary factor that determines voluntary behavioral choices, reward also strongly influences involuntary attentional control,” explained Shomstein. “In other words, the fruit that ends up on your kitchen counter was largely determined by a perceived reward.”

Something to think about the next time we unpack our grocery bags. 



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