I combine theory and methodology from economics, psychology, and neuroscience to understand how people decide, why they make wrong decisions, and how to make them better choosers. My research focused on how economic preferences change over the lifespan and contexts, including how thirst, being observed, outdoor luminance, as well as the structure of current and past choice affect behavior.
I have been awarded over $33 million in grants as a Chief Investigator, including ARC Centre of Excellence, DECRA, Discovery, and Linkage grants. In 2017 I received the Award from the Society for Neuroeconomics for my contributions to our understanding of decision-making.
Tymula A., Wang X., Imaizumi Y., Kawai T., Kunimatsu J., Matsumoto M. and Yamada H. (2023) Dynamic prospect theory – two core decision theories coexist in the gambling behavior of monkeys and humans Science Advances, 9(20)
Glimcher P. W. and Tymula A. (2023) Expected Subjective Value Theory (ESVT): A representation of decision under risk and certainty, Journal of Economic Behavior and Organization, 207: 110-128
Kettlewell N., Rijsdijk F., Siribaddana S., Sumathipala A., Tymula A., Zavos H., Glozier N. (2023) The impact of war and tsunami on risk aversion: Evidence from Sri Lankan twins, accepted at Applied Economics
Imaizumi Y., Tymula A., Tsubo Y., Matsumoto M. and Yamada H. (2022) A neuronal prospect theory model in the brain reward circuitry, Nature Communications, 13(5855)
Berger A. and Tymula A. (2022) Controlling ambiguity: The illusion of control in decision-making under risk and ambiguity [short poster presentation] Journal of Risk and Uncertainty 10.1007/s11166-022-09399-4
Cheung S. L., Tymula A., Wang X. (2022) Present Bias for Monetary and Dietary Rewards: Evidence from Chinese Teenagers, Experimental Economics, 25: 1202–1233
Kettlewell N. and Tymula A. (2021) The Australian Twins Economic Preferences Survey, Twin Research and Human Genetics
Guo J. and Tymula A. (2021) Waterfall illusion in risky choice, European Economic Review, 139
Heger S., Slonim R., Taush F. and Tymula A. (2021) Altruism among Consumers as Donors, Journal of Economic Behavior and Organization, 189: 611-622
Tymula A. and Wang X. (2021) Increased risk-taking, not loss tolerance, drives adolescents’ propensity to gamble more under peer observation, [supplement], Journal of Economic Behaviour and Organization, 188:439-457
Gainsbury S. M., Black N., Blaszczynski A., Callaghan S., Clancey G., Starcevic V., Tymula A. (2020) Reducing Internet gambling harms using behavioural science: A stakeholder framework, Frontiers in Psychiatry, section Addictive Disorders 11:598589
Weinrabe A., Chung H., Tymula A., Tranand J., Hickie I. (2020) Economic Rationality in Young People with Emerging Mood Disorder, Journal of Neuroscience, Economics, and Psychology
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
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
Rosato A. and Tymula A. (2019) Loss Aversion and Competition in Vickrey Auctions: Money Ain’t No Good, Games and Economic Behavior, 115: 188-208
Tymula, A. and Whitehair, J. (2018) Young adults gamble less when observed by peers, Journal of Economic Psychology, 68:1-15
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
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
Tymula, A. (2017) Competitive Screening of Heterogenous Labor Force and Corporate Teamwork Attitude. Journal of Institutional and Theoretical Economics, 173(3), 523-547
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
Tymula, A., Plassmann, H. (2016) Context-dependency in valuation. Current Opinion in Neurobiology, 40: 59-65
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, 9(2):65-77.
Gilaie-Dotan, S.,+ Tymula, A.,+ Cooper, N., Kable, J., Glimcher, P.W., Levy, I. (2014) Neuroanatomy predicts individual risk attitudes. Journal of Neuroscience, 34(37) (+shared first author, featured article)
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, 110(42)
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, 110(39) (+shared first author)
Großer, J., Reuben, E., Tymula, A. (2013) Political quid pro quo agreements: An experimental study. American Journal of Political Science, 57(3):582-597
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):17135-17140 (+ shared first author)
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
Kuhnen, C., and Tymula, A. (2012) Feedback, self-esteem and performance in organizations. Management Science, 58(1):94-113
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
Tymula A. (2017) Tolerance for ambiguity. In Moghaddam F.M. (Ed.) The SAGE Encyclopaedia of Political Behavior, SAGE Publications, Thousand Oaks CA
Tymula A. and Wang X. (2021) The years of living dangerously: can adolescents be encouraged away from risky behaviour? Sydney Business Insights
Tymula A. (2016) Financial gamble? My brain made me do it. The Conversation
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.
- 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
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
Papers under review
Cheung S., Tymula A., Wang X. (2021) Quasi-hyperbolic present bias: A meta-analysis [short poster presentation] revision requested from Management Science
Quasi-hyperbolic discounting is one of the most well-known and widely-used models to capture self-control problems in the economics literature. The underlying assumption of this model is that agents have a “present bias” toward current consumption such that all future rewards are downweighed relative to rewards in the present (in addition to standard exponential discounting for the length of delay). We report a meta-analytic dataset of estimates of the present bias parameter based on searches of all major research databases (62 papers with 81 estimates in total). We find that the literature shows that people are on average present biased for both monetary rewards (beta=0.82, 95% confidence interval of [0.74, 0.90]) and non-monetary rewards (beta=0.66, 95% confidence interval of [0.51, 0.85]) but that substantial heterogeneity exists across studies. The source of this heterogeneity comes from the subject pool, elicitation methodology, geographical location, payment method, mode of data collection (e.g. laboratory or field), and reward type. There is evidence of selective reporting and publication bias in the direction of overestimating the strength of present-bias (making estimates smaller), but present bias still exists after correcting for these issues (for money beta=0.87 with 95% confidence interval of [0.82, 0.92] after correcting for selective reporting).
Pastore C., Schurer S., Tymula A., Fuller N, Caterson I. (2023) Economic Preferences and Obesity: Evidence from a Clinical Lab-in-Field Experiment, revision requested from Health Economics
Many studies which describe the relationship between obesity and economic preference rely on healthy, clinically-irrelevant populations. Instead, we study economic decision-making of a clinically-relevant population of 299 people with obesity who participated in a six-months RCT in two Sydney-based hospitals to prevent diabetes onset. To elicit preferences, we use incentive-compatible experimental tasks that participants completed during their medical screening examination. In this population, we find that participants are risk averse, show no evidence of present bias, and have impatience levels comparable to healthy samples described in the international literature. Variations in present bias and impatience are not significantly associated with variations in markers of obesity. We find however a statistically significant negative association between risk tolerance and markers of obesity for women. Importantly, impatience moderates the link between risk tolerance and obesity, a finding which we are able to replicate in nationally-representative survey data. We discuss explanations for why our findings deviate markedly from the literature for this understudied but highly policy-relevant population. One explanation is that our specific population consists of forward-looking, well-educated individuals, who are willing to participate in an intensive health intervention. Hence, other factors may be at play for why these individuals live with obesity.
Kettlewell N. and Tymula A. (2023) Heritability across different domains of trust revision requested from the Journal of Economic Behavior and Organization
Using a large sample of 1,120 twins and the multivariate ACE-Cholesky model, we estimated the heritability of trust using four distinct measures of trust – domain-specific political trust, general self-reported trust, and incentivized behavioral trust and trustworthiness. Across the different measures of trust we consider, our estimates for heritability differ substantially, from 1% to 37%. Furthermore, the environmental correlates of trust also vary across the different measures with political trust having the largest set of environmental covariates. To reconcile the substantial differences in the estimated heritability of trust in the literature, we provide a meta-analysis of the heritability of behavioral and stated trust.
Kettlewell N., Levy J., Tymula A., Wang X. (2023) The gender reference point gap
Studies have frequently found that women are more risk averse than men. In this paper, we depart from usual practice in economics that treats risk attitude as a primitive, and instead adopt a neuroeconomic approach where risk attitude is determined by the reference point which can be easily estimated using standard econometric methods. We then evaluate whether there is a gender difference in the reference point, explaining the gender difference in risk aversion observed using traditional approaches. In our study, women make riskier choices less frequently than men. Compared to men, we find that women on average have a significantly lower reference point. By acknowledging the reference point as a potential source of gender inequality, we can begin a new discussion on how to address this important issue.
Rosato A. and Tymula A. (2021) A novel experimental test of truthful bidding in second-price auctions with real objects
We present experimental evidence on bidding in second-price auctions with real objects. Our novel design, combining a second-price auction with an individual-specific binary-choice task based on the outcome of the auction, allows us to directly identify over-and under-bidding. We analyze bidding in real-object and induced-value auctions, and find significant deviations from truthful bidding in both. Overall, under-bidding is somewhat more prevalent than over-bidding; yet, the latter has a bigger magnitude, especially with induced values. At the individual level, we nd no relation between the tendency to deviate from truthful bidding in induced-value vs. real-object auctions.
Less – 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