Post by Stephanie Williams
What's the science?
We know from animal studies that reward-related cues like noises (chimes) or visual signals (flashing lights) can influence animals to make risky decisions. It is still unknown if reward-related cues can influence humans in a similar way. It is also unclear how the cues would exert their effects on decision making. This week in the Journal of Neuroscience, Cherkasova and colleagues assessed the effects of reward-associated sensory cues on the promotion of risky decisions in humans.
How did they do it?
The authors randomized 131 human subjects to play two computerized games, either with or without visual (i.e. stacks of bills or coins) and auditory (casino chiming noises) cues, to test whether these cues affected decision making. The first game, the Iowa Gambling Task (IGT), consisted of four decks of cards, and the participant’s goal was to win as much money as possible by selecting cards from the decks. Some decks were more advantageous than others, and each time the participant selected a card, they either won or lost money. To win the maximum amount of money, participants should have chosen cards from the two of the four decks that had low risk/low reward cards (no big wins, but no big losses either). In the second game, the Vancouver Gambling Task (VGT), participants had to choose between a low chance of winning a larger amount of money, and a higher chance of winning a smaller amount of money. Participants were repeatedly presented with various pairs of potential winnings. The researchers used the participant’s choices in this task to create a model of a participants' willingness to take risks.
The authors tracked several physiological measurements including eye movements and pupil dilation, which is related to arousal. Eye tracking data was analyzed to measure time spent looking at probability information (participants were shown pie charts representing probabilities of winning during the VGT task). Pupil size was analyzed from the VGT to see whether the auditory and visual effects were related to pupil dilation, and whether dilation was related with riskier choices.
What did they find?
To understand the effect of the sensory cues on decision making, the authors applied various models that took into account different variables related to their data. They found that the presence of sensory cues did not cause subjects to make a greater number of disadvantageous choices in the IGT task. In contrast, during the VGT task, they found that subjects made riskier choices and spent less time paying attention to probability information when playing the cued task than when playing the uncued VGT task. The authors were able to relate the risk enhancement to subject’s decreased consideration of reward probability when making choices, rather than changes in the subject’s perceived expected value. It is still unclear what mechanism swayed participant's attention away from the probability information.
Several findings emerged from the authors analysis of pupil dilation during the VGT. In both the cued and uncued tasks, subjects showed increased pupil dilation during risky decisions. This was a significant finding, as it provides novel confirmation of a strong association between pupil dilation and risky choice. In the cued task, the authors found that pupil dilation associated with decision-making and anticipation was increased. This finding highlights the effect of the sensory cue in increasing arousal. The authors also found that the risk-promoting and arousal-promoting effects of cues were separate and independent effects.
What's the impact?
This is the first paper to confirm that sensory reward cues promote riskier decisions in humans. Previous studies had shown that reward sensory cues could increase arousal, and change the way people estimate profits, but no one had yet shown that they could directly affect choice. Their findings suggest that the sensory cues in particular environments (ie. Casinos) could affect decision making, which could be used to help explain why individuals suffering from addiction may make risky decisions.
Cherkasova, M. et al., Win-concurrent sensory cues can promote riskier choice. The Journal of Neuroscience (2018). Access the original scientific paper here.