Tinkelpaugh (1928) was a student of Tolman's in the Psychology Department at Berkeley (California). Monkeys saw a piece of banana or a piece of lettuce being hidden in a bucket shaped container. A few minutes later they were allowed to take the food item out of the container and eat it. The key to the experiment was that on occasional test trials the experimenter (unseen by the monkey) removed hidden banana and substituted lettuce. The animals reactions when they removed the lettuce were filmed. Their facial expressions and searching activities suggested that they were in some way "expecting" banana.

A drawing made from one of Tinkelpaugh's photographs is reproduced on page 126 of Shettleworth (1998)

She notes that Watanabe (1996) gave monkeys similar behavioural tests, and was able to record distinct patterns of cortical activity corresponding to the animals' expectations of raisin, apple, grape and many other foods.

There are many other confirmations of Watanabe's result (e.g. Holland and Gallaher, 2004), and so there is now considerable neurophysiological weight added to Tinkelpaugh's behavioural observations.


Baxter, M. G., & Murray, E. A. (2002). The amygdala and reward. Nature Reviews Neuroscience, 3(7), 563-573.

Gold, J. I. (2003). Linking reward expectation to behavior in the basal ganglia. Trends in Neurosciences, 26(1), 12-14.

Holland, P. C., & Gallagher, M. (2004). Amygdala-frontal interactions and reward expectancy. Current Opinion in Neurobiology, 14(2), 148-155.

Recent evidence indicates that networks including the amygdala and prefrontal cortex provide a key interface between affect and cognition. Converging evidence from rodents, humans, and non-human primates indicates that interconnections between the basolateral complex of the amygdala and the orbitofrontal cortex are crucial to the formation and use of expectancies of reinforcers in the guidance of goal-directed behavior.gif html version of this paper (log on first for access outside the College.)

Shettleworth, S.J. (1998) Cognition, Evolution, and Behavior. Oxford: Oxford University Press 591.5 SHE in Bk lib

Tinkelpaugh, O.L. (1928) An experimental study of representative factors in monkeys. Journal of Comparative Psychology, 8, 197-236.

Tremblay, L., & Schultz, W. (1999). Relative reward preference in primate orbitofrontal cortex. Nature, 398(6729), 704-708.

Watanabe, M. (1996). Reward expectancy in primate prefrontal neurons. Nature, 382(6592), 629-632.