Interactions between the elements of an outcome in human associative learning.

When a cue is established as a reliable predictor of an outcome (A–O1), this cue will typically blocklearning between an additional cue and the same outcome if both cues are subsequently trained together(AB–O1). Three experiments sought to explore whether this effect extends to outcomes and wasinvestigated using the food allergist paradigm in human participants. In all 3 experiments, an outcomefacilitation effect was observed. That is, prior learning about an element of an outcome compound(A–O1) facilitated learning about a novel outcome when (A–O2) these outcomes were presented together(A–O1 O2) relative to a control stimulus that first received C–O3 trials prior to C–O1 O2 trials. InExperiment 2, however, participants were also presented with an additional set of control trials, whichwere presented during Stage II only and reliably predicted the outcome compounds. At test, participantsdisplayed more learning about these additional control trials relative to the blocked outcomes, thusdisplaying an outcome blocking effect alongside an outcome facilitation effect. In Experiment 3, aone-trial outcome blocking procedure was used to distinguish theoretical accounts of these findings. Thisprocedure revealed an outcome facilitation effect but not an outcome blocking effect. These results canbe understood in terms of an account derived from Wagner’s (1981) model. The implications of thesefindings are discussed