I am a neuroeconomist and experimental economist and study how individuals make decisions. I am particularly fascinated by people sometimes making seemingly irrational decisions. I believe that many of these irrationalities can be rationally explained as a direct consequence of the limitations placed on our nervous system. I hope to understand how to minimise such irrationalities with smart choice architecture. My ultimate goal is to relate insights from my research to applied work, especially in the area of policy interventions, optimal organizational and incentives design, finance, political economics, and marketing.
Tymula (2019) Adolescents are more impatient and inconsistent, not more risk-taking when observed by peers – a comprehensive study of adolescent behavior under peer observation, Journal of Economic Behavior and Organisation, 166:735-750, October 2019 [full text]
Chung, H., Glimcher. P.W., Tymula, A. (2019) An Experimental Comparison of Risky and Riskless Choice – Limitations of Prospect Theory and Expected Utility Theory, American Economic Journal: Micro, 11(3):34-67, August 2019 [full text]
Rosato A. and Tymula A. (2019) Loss Aversion and Competition in Vickrey Auctions: Money Ain’t No Good, Games and Economic Behavior, 115, May 2019, 188-208 [full text]
Tymula, A. and Whitehair, J. (2018) Young adults gamble less when observed by peers, Journal of Economic Psychology, 68:1-15, October 2018 [full text]
Yamada H., Louie K., Tymula A. and Glimcher P.W. (2018) Free choice shapes normalized value signals in medial orbitofrontal cortex, Nature Communications, 9(1):162, January 2018 [full text]
Chung H., Tymula A., Glimcher P. (2017) The Reduction of Ventrolateral Prefrontal Cortex Grey Matter Volume Correlates with Loss of Economic Rationality in Aging, Journal of Neuroscience
Glimcher, P.W. and Tymula, A. (2017) Let the sunshine in? The effects of luminance on economic preferences, choice consistency and dominance violations. PLoS ONE, 12(8): e0181112, August 2017 [full text]
Tymula, A. (2017) Competitive Screening of Heterogenous Labor Force and Corporate Teamwork Attitude. Journal of Institutional and Theoretical Economics, 173(3), 523-547, September 2017 [full text]
Grubb M., Tymula A., Gilaie-Dotan S., Glimcher P. and Ifat Levy (2016) Neuroanatomy accounts for age-related changes in risk preferences. Nature Communications, 7, December 2016 [full text]
Tymula, A., Plassmann, H. (2016) Context-dependency in valuation. Current Opinion in Neurobiology, Volume 40, October 2016, p. 59-65 [full text]
Tymula, A., Woelbert, E., Glimcher, P.W. (2016) Flexible Valuations for Consumer Goods as Measured by the Becker-DeGroot-Marschak Mechanism. Journal of Neuroscience, Psychology, and Economics, Volume 9(2), June 2016, p.65-77. [full text]
Gilaie-Dotan, S.,+ Tymula, A.,+ Cooper, N., Kable, J., Glimcher, P.W., Levy, I. (2014) Neuroanatomy predicts individual risk attitudes. Journal of Neuroscience, Volume 34, Number 37, September 10, 2014 (+shared first author, featured article) [full text]
Tymula, A., Rosenberg Belmaker, L.A., Ruderman, L., Glimcher, P.W., Levy, I. (2013) Like cognitive function, decision-making across the lifespan shows profound age-related changes. Proceedings of the National Academy of Sciences, Volume 110, Number 42, October 15, 2013 [full text]
Yamada, H.+, Tymula, A.+, Louie, K., Glimcher, P.W. (2013) Thirst-dependent risk preferences in monkeys identify a primitive form of wealth. Proceedings of the National Academy of Sciences, Volume 110, Number 39, September 24, 2013 (+shared first author) [full text]
Großer, J., Reuben, E., Tymula, A. (2013) Political quid pro quo agreements: An experimental study. American Journal of Political Science, Volume 57, Number 3, July 2013, p. 582-597 [full text]
Tymula, A.+, Rosenberg Belmaker, L.A.+, Roy, A., Ruderman, L., Manson, K., Glimcher, P.W., Levy, I. (2012) Adolescents’ risk-taking behavior is driven by tolerance to ambiguity. Proceedings of the National Academy of Sciences 109 (42), October 2012, p. 17135-17140 (+ shared first author) [full text]
Levy, I., Rosenberg-Belmaker, L.A., Manson, K., Tymula, A., Glimcher, P.W. (2012) Measuring the subjective value of risky and ambiguous options using experimental economics and functional MRI methods. Journal of Visualized Experiments (67), September 2012 [full text]
Kuhnen, C., and Tymula, A. (2012) Feedback, self-esteem and performance in organizations. Management Science, 58 (1), January 2012, p. 94-113 [full text]
Published book chapters
Tymula A. (2019). Brain Morphometry for Economists: How do Brain Volume Constraints Affect Our Choices? in Biophysical Measurement in Experimental Social Science Research, Foster (Eds.), ELSEVIER
Tymula A. and Glimcher P.W. (2018). Emotions through the lens of economic theory. In Fox, A. S., Lapate, R. C., Shackman, A. J. & Davidson, R. J. (Eds.), The Nature of Emotion. Fundamental questions (2nd Edition). New York: Oxford University Press [full text]
Tymula A. (2017) Tolerance for ambiguity. In Moghaddam F.M. (Ed.) The SAGE Encyclopaedia of Political Behavior, SAGE Publications, Thousand Oaks CA [full text]
Tymula A. (2016) Financial gamble? My brain made me do it. The Conversation [full text]
Tymula, A. and Glimcher, P.W. (2015) Are adolescents really risk-takers? Most adults say yes, but the science is starting to say no. Frontiers for Young Minds. 3:3. [full text]
- featured on Scientific American Blog Network
- written for the Young Minds of the 2014 USA Science and Engineering Festival
Tymula A. (2014) Explainer: neuroeconomics, where science and economics meet. The Conversation [full text]
Book review of After Phrenology: Neural Reuse and the Interactive Brain, Michael L. Anderson. The MIT Press, Cambridge, MA, USA (2014) in Journal of Economic Psychology, Volume 51, December 2015, p. 279–280
Working papers under review
Robinson T. and Tymula, A. (2019) Divisive normalization of value explains choice-reversals in decision-making under risk [full text]
We present a neuroeconomic model for risky choice that species a utility function that is context-dependent. We demonstrate how and under what conditions the model generates choice (but not preference) reversals. In a laboratory experiment, we test the predictions of our model and compare it against other popular models of context-dependent choice. We nd that divisive normalization captures violations of the independence of irrelevant alternatives that cannot be otherwise explained with salience theory, range normalization, or attraction eect theories. Moreover, we identify a new setting in which the well-established attraction effects do not occur.
The finding that individuals are ambiguity averse in the domain of medium likelihood gains is robust across laboratory studies. We conducted a laboratory experiment to examine whether we can lower this aversion to ambiguity by giving participants an illusion of control over the probability of winning by allowing them to choose the winning color in what objectively are 50-50 gambles. We found that while our illusion of control manipulation does not increase participants’ preference for risky gambles with known probability of winning, it does increase participants’ tolerance for ambiguous gambles with unknown probability of winning. When the illusion of control is absent, the structural model estimates of ambiguity tolerance are 29% lower. Our results highlight the importance of considering the illusion of control in the estimation of ambiguity attitudes.
Glimcher P. W. and Tymula A. (2018) Expected Subjective Value Theory (ESVT): A representation of decision under risk and certainty, r&r [full text]
We present a descriptive model of choice with normative foundations based on how the brain is thought to represent value. An individual’s behavior is fully described by two primitives: an individual’s expectation and one free parameter we call “predisposition’. The model captures the same apparent preference phenomena illustrated by Prospect Theory but unlike Prospect Theory accounts for individual heterogeneity in parameters, employs far fewer parameters than full prospect theory, and retains neurobiological plausibility as a causal model of the choice process. Additionally, our theory makes a series of novel predictions amenable to future testing and includes an alternative explanation for endowment effect.
Guo J. and Tymula A. (2019) Waterfall illusion in risky choice [full text]
Based on recent discoveries in economics and neuroscience, we hypothesize that pure exposure to high-value or low-value rewards can change people’s risk attitudes and confirm this hypothesis in a laboratory experiment. We find that we can manipulate an individual’s valuation of a gamble through a prior brief and payoff-irrelevant exposure to low-value or high-value rewards. In particular, participants provide higher valuations for the same gambles after they have been exposed to low-value rewards than after they have been exposed to high-value rewards within the same experimental session. These results are consistent with the current understanding of how the nervous system encodes rewards and imply that even brief experiences that do not change wealth can impact individual risk attitudes.
Kettlewell N., Rijsdijk F., Siribaddana S., Sumathipala A., Tymula A., Zavos H., Glozier N. (2019) The impact of war and tsunami on risk aversion: Evidence from Sri Lankan twins [full text]
We estimate whether risk preferences are affected by traumatic events by using a unique survey of Sri Lankan twins which contains information on individual’s exposure to the 2004 Indian Ocean Tsunami, participation as a combatant in the civil war, validated measures of mental health and risk preferences, and a rich set of control variables. Our estimation strategy utilises variation in experiences within twin pairs and allows us to explore wealth shocks and/or changes in mental health as mechanisms. We find that both events lead to less risk aversion, a result that is not driven by mental health or wealth changes.
Weinrabe A., Chung H., Tymula A., Tranand J., Hickie I. (2015) Economic Rationality in Young People with Emerging Mood Disorder, r&r at the Journal of Neuroscience, Economics, and Psychology
Cognitive difficulties are common in persons experiencing anxiety or mood disorders. In this paper, we explore the economic concept of rational decision-making in young people with emerging mood disorders by using incentive-compatible experiments involving choices over consumer products. At two time points, separated by six to eight weeks, we measured rational decision-making (defined as lack of violations of the Generalized Axiom of Revealed Preference) concurrently with levels of anxiety and depression levels (using standard scales: Kessler Psychological Distress (K10); Quick Inventory of Depressive Symptomology (QIDS-A17) and Somatic and Psychological Health Report (SPHERE-12)) in 30 persons attending a youth mental health clinic. We then explored correlations between changes in mood and changes in economic rationality. Young people with more severe symptoms demonstrated greater deviations from rational decision-making. These results may have implications for both the diagnosis and treatment of common mood disorders in young people.
Antrobus E., Baranov V., Cobb-Clark D., Mazerolle L. and Tymula A. (2017) The Risk and Time Preferences of Young Truants and Their Parents [full text]
We use an incentivized experiment to measure the risk and time preferences of truant adolescents and their parents. We find that adolescent preferences do not predict school attendance and that a unique police-school partnership program targeting school absences was most effective in reducing the truancy of adolescents with relatively risk-averse parents.
Non – traditional research output
Decision-making and ageing exhibit at the Museum of the National Academy of Sciences in Washington, DC (part of the Life Lab exhibit)
- on display May 2012 – September 2018