Ian Krajbich • UCLA Department of Psychology

June 15, 2023

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Associate Professor
Primary Area: Cognitive Psychology
Secondary Area(s): Social and Affective Neuroscience
Email: krajbich@ucla.edu
Lab Website: https://krajbichlab.psych.ucla.edu

Research and Teaching Interests:

When people make decisions, they don’t immediately know what to choose. Instead, they evaluate their options over time, gathering and comparing evidence in their support. This choice process relies on visual attention, memory, reward associations, goal alignment, strategic considerations, etc. When it’s less obvious which option to choose, people take longer to decide and shift their attention back and forth between the options.

In the Krajbich lab, we study the choice process to better understand people’s preferences. We develop and test mathematical models of the choice process, drawing on insights from economics, psychology, neuroscience, and marketing. These models incorporate choice-process measures like response times, eye tracking, mouse tracking, and brain imaging, to better predict people’s choices. We study all types of choices, but mostly ones having to do with preferences. These decisions range from choosing between snack foods in the lab, to bargaining over goods on eBay. A key insight from our work is that decision-making is a continuously evolving, noisy process, and so can yield systematically different choices over time. This challenges the standard notion that people have stable preferences, but also the behavioral notion that people use heuristics or rules to make their decisions.

Biography:

Ian obtained his B.S. in Physics and Business Economics & Management at Caltech, then stayed at Caltech do his M.Sc. in Social Sciences and Ph.D. in Behavioral and Social Neuroscience under the guidance of Antonio Rangel, Colin Camerer, Ralph Adolphs and John Ledyard. After leaving Caltech, he spent 2011-2013 in Switzerland at the University of Zurich doing a postdoc with Ernst Fehr. From 2013-2023, he was a faculty member at The Ohio State University (OSU) in the Department of Psychology and the Department of Economics. From 2019-2023 he also served as the Director of OSU’s Decision Sciences Collaborative.

Curriculum Vitae

Representative Publications:

Shevlin, B., Smith, S.M., Hausfeld, J., Krajbich, I. (2022) High-value decisions are fast and accurate, inconsistent with diminishing value sensitivity. Proceedings of the National Academy of Sciences of the USA, doi.org/10.1073/pnas.2101508119
Yang, X. & Krajbich, I. (2022) A dynamic computational model of gaze and choice in multi-attribute decisions. Psychological Review, doi.org/10.1037/rev0000350
Desai, N. & Krajbich, I. (2021) Decomposing preferences into predispositions and evaluations. Journal of Experimental Psychology: General, doi.org/10.1037/xge0001162
Frydman, C. & Krajbich, I. (2021) Using response times to infer others’ private information: An application to information cascades. Management Science, doi/10.1287/mnsc.2021.3994
Thomas, A.W., Molter, F., Krajbich, I. (2021) Uncovering the computational mechanisms underlying many-alternative choice. eLife, 10:e57012
Stillman, P.E., Krajbich, I., Ferguson, M.J. (2020) Using dynamic monitoring of choices to predict and understand risk preferences. Proceedings of the National Academy of Sciences of the USA, 117(50): 31738-31747.
Konovalov, A. & Krajbich, I. (2020) Mouse tracking reveals structure knowledge in the absence of model-based choice
Nature Communications, 11: 1893
Krajbich, I. (2019) Accounting for attention in sequential sampling models of decision making Current Opinion in Psychology, 29: 6-11
Smith, S. & Krajbich, I. (2019) Gaze amplifies value in decision making Psychological Science, 30(1): 116-128
Chen, F., & Krajbich, I. (2018) Biased sequential sampling underlies the effects of time pressure and delay in social decision making Nature Communications, 9:3557
Konovalov, A. & Krajbich, I. (2018) Neurocomputational Dynamics of Sequence Learning. Neuron, 98, 1-12
Krajbich, I., Hare, T., Bartling, B., Morishima, Y., & Fehr, E. (2015). A common mechanism underlying food choice and social decisions. PLoS Computational Biology, 11(10): e1004371
Krajbich, I., Bartling, B., Hare, T., & Fehr, E. (2015). Rethinking fast and slow based on a critique of reaction-time reverse inference. Nature Communications, 6:7455
Krajbich, I., Oud, B., Fehr, E. (2014). Benefits of neuroeconomics modeling: New policy interventions and predictors of preference. American Economic Review: Papers & Proceedings, 104(5), 501-506
Krajbich, I., Rangel, A. (2011). Multialternative drift-diffusion model predicts the relationship between visual fixations and choice in value-based choice. Proceedings of the National Academy of Sciences, 108(33), 13852-13857
Krajbich, I., Armel, C., Rangel, A. (2010). Visual fixations and the computation and comparison of value in simple choice. Nature Neuroscience, 13(10), 1292-1298
Krajbich, I., Camerer, C., Ledyard, J., Rangel, A. (2009). Using neural measures of economic value to solve the public goods free-rider problem. Science, 326(5952), 596-599