Thomas Graeber

Photo Thomas Graeber I am an Assistant Professor at Harvard Business School.
My research is in behavioral and experimental economics.

Please find my [CV here]. Contact me at [tgraeber@hbs.edu].




Research


Cognitive Uncertainty
with Benjamin Enke
[abstract]   [pdf]   [coverage: The Economist  ·  VoxEU]
Because many economic decisions are difficult, people may exhibit cognitive uncertainty: subjective uncertainty about what the optimal action is. In the presence of such cognitive uncertainty, people implicitly compress objective probabilities towards a cognitive default of 50:50. By experimentally measuring and exogenously manipulating cognitive uncertainty, this idea brings together and partially explains a set of striking similarities in well-known behavioral anomalies in choice under risk, choice under ambiguity, belief updating, and survey forecasts of economic variables. Structural estimations show that the pronounced inverse S-shaped response patterns that pervade these literatures result from how cognitive uncertainty varies with objective probabilities.


Inattentive Inference
[abstract]   [pdf]   [additional material]
This paper studies how people make inference about a state of the world when the information structure includes additional, payoff-irrelevant states. For example, learning about effort from observed performance may require accounting for the otherwise irrelevant role of luck. This creates an attribution problem that is common to information structures with multiple causes. We report controlled experimental evidence for pervasive overinference about states that affect utility given an action, providing an explanation for a collection of well-known but previously unconnected misattribution patterns. In studying why systematic misattribution arises, we consistently find that errors are not due to excessive task complexity or deliberate effort avoidance. Instead, people form incomplete mental models of the information structure and fail to notice the need to account for alternative causes. These mental models are not stable but context-dependent: misattribution responds to a variety of attentional manipulations, but not to changes in the costs of inattention.


Heterogeneity of Gain-Loss Attitudes and Expectations-Based Reference Points
with Lorenz Goette, Alex Kellogg and Charles Sprenger
[abstract]   [pdf]
This project examines the role of heterogeneity in gain-loss attitudes for identifying models of expectations-based reference dependence (Kőszegi and Rabin, 2006, 2007) (KR). Different gain-loss attitudes lead to different signs for KR comparative statics. Failure to account for the known heterogeneity in gain-loss attitudes is a central confounding factor challenging prior tests of the KR model conducted under the assumption of universal loss aversion. We document heterogeneous treatment effects over gain-loss types in both an initial experiment and an exact replication. Recognizing heterogeneity over types allows us to both recover the KR model’s central predictions, and account for inconsistency across prior empirical tests.


Bayesian signatures of confidence and central tendency in perceptual judgment
with Yang Xiang, Benjamin Enke and Samuel Gershman
[abstract]   [pdf]
Despite a surge of interest in theoretical models of Bayesian cognition, direct empirical evidence for their validity remains limited. This paper studies Bayesian signatures in perceptual judgment, focusing on the central tendency effect: perceptual judgments are consistently biased towards the center of the stimulus distribution. Based on a formal Bayesian framework, we show that lower subjective confidence as a measure of posterior uncertainty about a judgment predicts (i) a lower sensitivity of magnitude estimates to objective stimuli; (ii) a higher sensitivity to the mean of the stimulus distribution; (iii) a stronger central tendency effect at higher stimulus magnitudes; and (iv) higher response variability. To test these predictions, we collect a tailored large-scale experimental data set and additionally re-analyze perceptual judgment data from several previous experiments. Across data sets, subjective confidence is strongly predictive of the central tendency effect and response variability, both correlationally and when we exogenously manipulate the magnitude of sensory noise. Our results lend support to Bayesian explanations of both confidence and the central tendency effect.


Delayed Negative Effects of Prosocial Spending on Happiness
with Armin Falk   (Proceedings of the National Academy of Sciences, 2020, vol. 117 (12), pp. 6463-6468)
[abstract]   [pdf]   [coverage: CNN  ·  Deutschlandfunk  ·  Frankfurter Allgemeine WOCHE  ·  la Repubblica]
Does prosocial behavior promote happiness? We test this longstanding hypothesis in a behavioral experiment that extends the scope of previous research. In our Saving a Life paradigm, every participant either saved one human life in expectation by triggering a targeted donation of 350 euros or received an amount of 100 euros. Using a choice paradigm between two binary lotteries with different chances of saving a life, we observed subjects’ intentions at the same time as creating random variation in prosocial outcomes. We repeatedly measured happiness at various delays. Our data weakly replicate the positive effect identified in previous research but only for the very short run. One month later, the sign of the effect reversed, and prosocial behavior led to significantly lower happiness than obtaining the money. Notably, even those subjects who chose prosocially were ultimately happier if they ended up getting the money for themselves. Our findings revealed a more nuanced causal relationship than previously suggested, providing an explanation for the apparent absence of universal prosocial behavior.