More is more, or is there more to it? Frequency moderations in evaluative conditioning depend on variation in the unconditioned stimuli

Evaluative conditioning (EC) is an experimental paradigm that models the acquisition of attitudes based on co-occurrences between conditioned stimuli (CSs) and unconditioned stimuli (USs). It has been noted that EC effects can be mediated by different forms of representations. Whereas stimulus-stimulus (S S) representations bring about an evaluative response via the CS's link to the specific US that it co-occurred with at learning, stimulus-valence (S V) representations entail a direct link between the CS and the valence category the US belongs to. The prevalence of these representations depends on US variability: S S representations are facilitated by procedures that repeat the same US at each presentation of the CS, S V representations are facilitated when a new US occurs at each pairing instance. The present research investigates whether EC effects develop differently depending on the variability of USs. Specifically, S S representations should emerge rapidly, whereas the abstraction underlying S V representations should benefit from repeated pairing instances. Across four experiments, we observed robust, largely valence-symmetric frequency moderations when a new US was shown at each pairing instance. In contrast, frequency moderations were generally absent when the same US was repeated, except in a procedure that intermixed same-US and different-USs pairings. These findings indicate that frequency and variability jointly shape EC effects and that such effects are mediated by the active construal of CS–US relations. This framework integrates previously inconsistent findings and underscores the theoretical importance of ecological variables and representational format for evaluative learning outcomes.