The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 17 No. 4 • May 2014

A Recent Study Cleverly Shows How Excessive Optimism Bias Works in Birds

The recognition that people are prone to an optimism bias, expecting more positive outcomes than what objective data would suggest, resulted in a fascinating study of certain birds that was described in The Optimism Bias: A Tour of the Irrationally Positive Brain by Tali Sharot (a scientist who has done considerable original research in this field), Pantheon Books, 2011.

In this experiment,1 the researchers wanted to see whether birds would have an optimism bias like people often do. Naturally it required a cleverly designed experiment since they couldn’t just ASK the birds. They got the information by this ingenious approach: They trained birds to press a blue lever whenever they heard a short tone (2 seconds) and the birds would receive an immediate food reward after pressing the blue lever. They also trained the birds to press a red lever when they heard a long tone (10 seconds), which would result in a food reward following a delay. The birds were not happy waiting for the food during the delay and associated the long tone with a negative outcome.

The birds had to get their response right. If they pressed the wrong lever, they didn’t get any food. The big question was how the birds would respond to a tone that was neither short nor long but ambiguously somewhere in the middle. The researchers wondered whether they would be “optimistic” by pressing the blue lever or “pessimistic” by pressing the red lever. In fact, the ambiguous tone tended to result in the birds pressing the blue lever, in the absence of anything that would tell them what the outcome would be. And, the real eye opener was that only birds living in the larger, cleaner cages with toys and continuous reliable access to food, water, and baths were “optimistic.” Birds living in smaller, less clean cages with unreliable access to these comforts tended to be more “realistic” and to have more accurate expectations. The researchers interpreted this as a “depressive realism” derived from living in more difficult conditions

The experiment very skillfully permitted the researchers to perceive the birds’ future expectations and how remarkably similar to the human optimism bias it was. We can extrapolate from that to the unrealistically optimistic view of government programs that we so frequently see inexplicably (it would seem) from those with higher incomes and educational attainment. The larger houses with the enriched environments that such people live in appears to have a similar effect (excessively optimistic bias) to that of the birds living in the larger, more enriched cages.


  1. pp. 37 & 38, book cited above. Original study: Matheson, Asher, and Bateson. Larger, enriched cages are associated with ‘optimistic’ response biases in captive European starlings (Sturnus vulgaris). Appl Anim Behav Sci. 109:374-83 (2008).

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