Theory and Decision

, Volume 54, Issue 4, pp 287–314 | Cite as

Verbal and Behavioral Learning in a Probability Compounding Task

  • Daniel John Zizzo


The conjunction fallacy occurs whenever probability compounds are thought of as more likely than its component probabilities alone. In the experiment we present, subjects chose between simple and compound lotteries after some practice. Depending on the condition, they were given more or less information about the nature of probability compounds. The conjunction fallacy was surprisingly robust. There was, however, a puzzling dissociation between verbal and behavioral learning: verbal responses were sensitive, but actual choices entirely insensitive, to the amount of verbal instructions being provided. This might reflect a dichotomy between implicit and explicit learning. Caution must be exercised in generalizing results from what people say to what people do.

conjunction fallacy heuristics learning probability compounding 


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  1. Abelson, R.P., Leddo, J. and Gross, P.H. (1987), The strength of conjunctive explanations, Personality and Social Psychology Bulletin 13(2), 141–155.Google Scholar
  2. Fantino, E. and Savastano, H. (1996), Humans' responses to novel stimulus compounds and the effects of training, Psychonomic Bulletin and Review 3(2), 204–207.Google Scholar
  3. Fantino, E., Kulik, J., Stolarz-Fantino, S. and Wright, W. (1997), The conjunction fallacy: A test of averaging hypotheses. Psychonomic Bulletin and Review 4(1), 96–101.Google Scholar
  4. Friedman, M. (1953), Essays in Positive Economics. Chicago: Irwin.Google Scholar
  5. Hertwig, R. and Gigerenzer, G. (1999), The ‘conjunction fallacy’ revisited: How intelligent inferences look like reasoning errors, Journal of Behavioral Decision Making 12(4), 275–305.Google Scholar
  6. Hoel, P.G. (1984), An Introduction to Mathematical Statistics. New York, Wiley.Google Scholar
  7. Massaro, D.W. (1994), A pattern recognition account of decision making, Memory and Cognition 22(5), 616–627.Google Scholar
  8. Mellers, B., Hertwig, R. and Kahneman, D. (2001), Dofrequency representations eliminate conjunction effects? An exercise in adversarial collaboration, Psychological Science 12(6), 269–275.Google Scholar
  9. Mulford, M. and Dawes, R.M. (1999), Subadditivity in memory for personal events, Psychological Science 10(1), 47–51.Google Scholar
  10. Shanks, D.R. and St. John, M.F. (1994), Characteristics of dissociable human learning systems, Behavioral and Brain Sciences 17(3), 367–447.Google Scholar
  11. Tversky, A. and Kahneman, D. (1982), Judgements of and by representativeness, In: Kahneman, D. Slovic, P. and Tversky A. (eds.), Judgement Under Uncertainty: Heuristics and Biases. New York: Cambridge University Press.Google Scholar
  12. Tversky, A. and Kahneman, D. (1983), Extensional versus intuitive reasoning: the conjunction fallacy in probability judgement, Psychological Review 90(4), 239–315.Google Scholar
  13. Zizzo, D.J. (2000), Implicit learning of (boundedly) rational behaviour, Behavioral and Brain Sciences 23(5), 700–701.Google Scholar
  14. Zizzo, D.J. (2001), Choices Between Simple and Compound Lotteries: Experimental Evidence and Neural Network Modelling, Discussion Paper no. 57. Department of Economics, Oxford: University of Oxford.Google Scholar
  15. Zizzo, D.J. (2002), Probability Compounding in Words and in Practice. Discussion Paper no. 88. Department of Economics, Oxford: University of Oxford.Google Scholar
  16. Zizzo, D.J., Stolarz-Fantino, S., Wen, J. and Fantino, E. (2000), A violation of the monotonicity axiom: Experimental evidence on the conjunction fallacy, Journal of Economic Behavior and Organization 41(3), 263–276.Google Scholar

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • Daniel John Zizzo
    • 1
  1. 1.Department of EconomicsUniversity of OxfordOxfordUnited Kingdom

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