How Animals Understand Probabilities


The “Monty Hall Dilemma” (MHD) is a well known probability puzzle in which a player tries to guess which of three doors conceals a desirable prize. After an initial choice is made, one of the remaining doors is opened, revealing no prize. The player is then given the option of staying with their initial guess or switching to the other unopened door. Most people opt to stay with their initial guess, despite the fact that switching doubles the probability of winning. A series of experiments investigated whether pigeons (Columba livia), like most humans, would fail to maximize their expected winnings in a version of the MHD. Birds completed multiple trials of a standard MHD, with the three response keys in an operant chamber serving as the three doors and access to mixed grain as the prize. Across experiments, the probability of gaining reinforcement for switching and staying was manipulated, and birds adjusted their probability of switching and staying to approximate the optimal strategy. Replication of the procedure with human participants showed that humans failed to adopt optimal strategies, even with extensive training.

Introduction (Via Whitman)

Animals are frequently presented with choices where the outcomes associated with each option are ambiguous and probabilistically determined. A classic example is the decision of where to forage for food: a location that has the signs of being food-rich might recently have been picked clean, and a location that appears to be food-poor might contain an unseen cache. Thus, an animal cannot be absolutely certain of the outcome of its choice. A low-probability or “bad” choice might yield a favorable outcome, and a high-probability or “good” choice might produce disastrous results. However, even if the chooser cannot be absolutely certain, many of these choices are associated with a particular probability of success.

Finding (via whitman)

This finding is consistent with other investigations of suboptimal choice behaviors. For example, Langer and Imber (1979) have shown that overpractice can produce a seemingly paradoxical decrement in performance. They characterize the decrement as a negative consequence of the otherwise adaptive tendency for overlearning to free up limited attentional resources. Thus, the benefits that come with extensive education may partly be due to the acquisition of heuristics that while efficient, can interfere with some kinds of performance, perhaps including the MHD.

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27. February 2010 by Miguel Barbosa
Categories: Curated Readings, Risk & Uncertainty | Leave a comment

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