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Monday, July 20 • 7:00pm - 8:00pm
P215: Loss aversion and outcome-value encoding: A negative association between posterior insula activity and loss aversion coefficient

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Link to Google Meeting: https://meet.google.com/ona-iwxv-ugf

Update 19Jul2020: A different version of poster is uploaded for better readability. 

Ka Chun Wu
, Isaac Ip, Fiona Ching, Heytou Chiu, Rosa Chan, Savio Wong

In prospect theory, loss aversion is one important parameter that modulates one's decision in involving risk. Previous studies find that amygdala activity is related to the degree of loss aversion during the action-selection processes. However, there is little if any study that look into the reaction to outcome that could affect the reinforcement learning process. In this study, we examine the brain response associated with decision outcome and how that varies across subjects with different degrees of loss aversion. We expect that people with high loss aversion experience stronger emotional impact when receiving a negative outcome after taking risk. We hypothesize a person’s degree of loss aversion could be reflected by the BOLD contrast across decision outcomes.

To test this hypothesis, we recorded and analysed the fMRI data of twenty-three participants (10 males and 13 females; Mage = 17.78 ± 0.52) during the Loss Aversion Task (LAT) [1]. The LAT was implemented with a rapid event-related design in which participants were given two options: NoGamble option with a guaranteed outcome and Gamble with 50% chance of getting a better-than-NoGamble outcome and 50% chance of getting a worse-than-NoGamble outcome (Fig. 1A). The utility of the two options varied so that one option has higher or equal utility respect to another. Participants were presented with a feedback indicating the outcome. Loss aversion coefficient (lambda; ƛ= −beta loss / beta gain) is estimated by fitting the behavioural responses to the logistic function. A higher lambda value indicates stronger loss aversion, with ƛ = 1 meaning equal weight for gain and loss.

We find significantly stronger activation at nucleus accumbens (NAcc) for gambling outcome (win or loss) than guaranteed outcome, but find no significant difference among the valence of feedback (gain verse loss). Condition contrasts reveal that the activity of the left posterior insular cortex [2], an area found to be related to emotional salience and memory, during gambling outcome relative to guaranteed outcome is negatively correlated with participants’ lambda (Fig. 1B). Although it is unclear about the causal relationship, we propose that gambling outcome is more salient in those subject with weaker loss aversion, which reflect a higher chance of it influencing their future decision [3]. In contrast, people with strong loss aversion are weaker in differentiating gambling outcome and guaranteed outcome in terms of their salience, and thus lead to relatively higher utility for the safe option in a long run.  In conclusion, the individual difference in loss aversion could be capture by condition contrasts in a LAT and gives insight to the model of outcome-value encoding.

References
1. Tom SM, Fox CR, Trepel C, Poldrack RA. The neural basis of loss aversion in decision-making under risk. Science. 2007; 315(5811): 515-518.
2. Menon V, Uddin LQ. Saliency, switching, attention and control: a network model of insula function. Brain Structure and Function, 2010, 214; 655-667.
3. Canessa N, et al. Neural markers of loss aversion in resting-state brain activity. NeuroImage. 2017;146: 257-265.


Speakers
KC

Ka Chun Wu

MPhil student, Department of Educational Psychology, The Chinese University of Hong Kong



Monday July 20, 2020 7:00pm - 8:00pm CEST
Slot 02