Combination rules in multiple-cue probability learning : II, performance, confidence and development of rules

Armelius, B-Å., and Armelius, K. Combination rules in multiple-cue probability learning. II. Performance, confidence and development of rules. Umeå Psychological Reports No. 101, 1976. - Subjects' use of combination rules was studied in five two-cue multiple-cue probability learning tasks with varying degrees of predictability. Subjects were asked to state how they made their predictions at different times during the experiment. 70 % of the subjects formulated systematic and consistent combination rules, while the remaining 30 % formur lated rules that were incomplete or inconsistent. The verbal statements were found to account for the subject's actual judgments in 86 % of the cases. About 50 % of the rules were single rules, with one rule coveming the complete cue matrix and the rest were multiple rules with different rules being used for different parts of the cue matrix. Performance and confidence were higher for subjects who had formulated systematic combination rules. The results of the experiment were analyzed in terms of a two-stage model for inference behavior. According to this model subjects sample their first combination rule from a hierarchy of hypotheses about relations between cues and criterion. Frequent hypotheses in that hierarchy seem to be average, sum and difference of the two cue values. In the second stage subjects test their hypotheses or develop them through their experience with the task. In the present experiment there was some evidence that subjects using multiple rules construct their rules on the basis of their experience with the task, especially in tasks with high predictability.digitalisering@um