Monetary significance of the affiliative smile: A case for reciprocal altruism


Whether smiling could accrue monetary returns was tested. Two degrees of smiling to single men and women (N = 96) by a waitress in a cocktail lounge was evaluated in terms of number of drinks ordered, size of tip, and whether the customers smiled upon departure. A broad smile reaped more money than a minimal smile and more from men than from women patrons. The results are discussed in terms of reciprocal altruism.


  1. Chapman, A. J., & Chapman, W. A. Responsiveness to humor: Its dependency upon a companion’s humorous smiling and laughter. Journal of Psychology, 1974, 88, 245–252.

    Article  Google Scholar 

  2. Davis, J. N., & Farina, A. Humor appreciation as a social communication. Journal of Personality and Social Psychology, 1970, 15, 175–178.

    Article  Google Scholar 

  3. Ekman, P. Universals and cultural differences in facial expressions of emotion. Nebraska Symposium on Motivation, 1971, 207–283.

  4. Lockard, J. S., Fahrenbruch, C. E., Smith, J. L., & Morgan, C. J. Smiling and laughter: Different phyletic origins. Bulletin of the Psychonomic Society, 1977, 10, 183–186.

    Google Scholar 

  5. Lockard, J. S., McVittie, R. I., & Isaac, L. M. Functional significance of the affiliative smile. Bulletin of the Psychonomic Society, 1977, 9, 367–370.

    Article  Google Scholar 

  6. Pedersen, D. M., & Heaston, A. B. The effects of sex of approaching person, of the subject, and angle of approach upon personal space. Journal of Psychology, 1972, 82, 277–286.

    Article  Google Scholar 

  7. Sroufe, L. A., & Waters, E. The ontogenesis of smiling and laughter: A perspective on the organization of development in infancy. Psychological Review, 1976, 83, 173–189.

    PubMed  Article  Google Scholar 

  8. Trivers, R. L. The evolution of reciprocal altruism. Quarterly Review of Biology, 1971, 46, 35–57.

    Article  Google Scholar 

  9. Wilson, E. O. Sociobiology. Cambridge, Mass: Belknap Press of Harvard University Press, 1975.

    Google Scholar 

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Correspondence to Kathi L. Tidd.

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Tidd, K.L., Lockard, J.S. Monetary significance of the affiliative smile: A case for reciprocal altruism. Bull. Psychon. Soc. 11, 344–346 (1978).

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  • Personal Space
  • Monetary Benefit
  • Monetary Return
  • Reciprocal Altruism
  • Mouth Corner