Anchoring

We submitted the “african countries problem” from Tversky and Kahneman (1974) to 152 workers (61.2% women, mean age = 35.4). Participants were paid $0.05 for a HIT that comprised other unrelated brief tasks. Approximately half of the participants was asked the following question:

Do you think there are more or less than 65 African countries in the United Nations?

The other half was asked the following question:

Do you think there are more or less than 12 African countries in the United Nations?

Both the groups were then asked to estimate the number of African countries in the United Nations.

As expected, participants exposed to the large anchor (65) provided higher estimates than participants exposed to the small anchor (12), F(1,150) = 55.99, p < .001. Therefore, we were able to replicate a classic anchoring effect –  our participants’ judgments are biased toward the implicitly suggested reference points. It should be noted that means in our data (42.6 and 18.5 respectively) are very similar to those recently published by Stanovich and West (2008; 42.6 and 14.9 respectively).

References

Stanovich, K. E., West. R. F. (2008). On the relative independence of thinking biases and cognitive ability. Journal of Personality and Social Psychology, 94, 672-695.

Tversky, A., Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185, 1124-1131.