Effects of trial order on contingency judgments: A comparison of associative and probabilistic contrast accounts

Four experiments examined trial sequencing effects in human contingency judgment. In Experiments 1-3, ratings of contingency between a target cue and outcome were affected by the presentation order of a series of trials distributed in 2 distinct blocks and showed a recency bias. Experiment 4 replicated this effect when the trials were partly intermixed. These recency effects are predicted by an associative learning model that computes associative strengths trial by trial and incorporates configural coding of cues but are problematic for probabilistic contrast accounts, which currently have no provision in the contingency computation for the differential weighting of trials as a function of their order of presentation.