Highlighting Faculty Member Ian Krajbich


Date published: 04/01/24

When we make decisions, we often don’t immediately know what to choose. What is the process by which we evaluate and compare our options? My work combines choice-process data and computational modeling to understand how we gather and process information while making preference-based decisions. 

Much of my research is based on the drift-diffusion model (DDM) idea that the decision process involves an accumulation of relative evidence or support for each alternative. That process is influenced by limited attention, the ability to access subjective values/attitudes, and prior information about the options. The process can be studied from its physical manifestations in the form of hand movements (via mouse tracking), eye movements (via eye tracking) and brain activity (via brain imaging), as well as more traditional measures such as choice probabilities and reaction times (RT). As one notable example, our research shows that gaze amplifies value information, increasing reward and decision signals in the prefrontal cortex, and biasing choice.

In addition to providing a basic understanding of how people make many of their decisions, our lab’s approach allows us to quantitatively predict choice and RT across domains, to understand the effects of time pressure on behavior, to predict the effects of attention manipulations on choice, to use RT and mouse tracking to quickly infer people’s preferences, to understand how nudges really affect behavior, and so on.   

I also have research in reinforcement-learning and Bayesian updating, because I am interested in how people learn what they like (or don’t like), and how they detect patterns in the world, allowing them to more efficiently attend to relevant information. Currently I am interested in how people learn information from others, how well they use others’ non-verbal cues to infer confidence or preference strength, and how they might strategically manipulate those signals to fool others. Our lab studies this both in the lab and in real markets like eBay. 

Bio: Ian was born in Toronto but mostly grew up in Portland (Oregon).  He 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 studying the dynamics of social preferences. 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. He moved to UCLA in the summer of 2023. Outside of the lab, he enjoys biking along the beach, hiking and skiing in the mountains, attending rock concerts, and exploring the craft beer and food scenes.    

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