Francis W. Irwin

Effects of probabilistic independent outcomes upon predictions

Ss won or lost 10 cents for correct and incorrect predictions of draws from binary packs. The draws also had independent outcome values (IO’s) that depended upon the cards drawn but not upon the predictions. These IO’s were probabilistic, with expected values ranging from 10 cents to −10 cents. Cards with positive IO were predicted significantly more often than cards with negative IO, with objective probability constant.

Buying insurance in an urn-scheme experiment

The Ss drew from urns containing 50, 74, or 99 blue balls and one yellow ball and gained money unless they drew the yellow ball before completing 50 draws. Insurance of zero expected value against the yellow ball was bought increasingly as draws from an urn proceeded.

Effects of independent outcome-values of past events upon subsequent choices

Choices made by human Ss in two experiments showed that their beliefs as to which of two alternative outcomes of a probabilistic event had occurred in the past were affected by the preference values that these outcomes possessed prior to the occurrence of the event.