Acquiring favorable attitudes based on aversive affective cues: Examining the spontaneity and efficiency of propositional evaluative conditioning

Most research in evaluative conditioning (EC) documents that a target object (conditioned stimulus, CS) acquires the same valence as a co-occurring affective cue (unconditioned stimulus, US). Some recent studies in EC have found that a CS may acquire the opposite valence as a US when people process a negational relation between the CS and the US, supporting a propositional learning mechanism for EC. However, these prior studies involved explicitly instructing respondents to assume that the CS opposes (e.g., “prevents”) the presented US. The present studies investigate whether and when people will spontaneously process an implied negational relation between co-occurring stimuli (e.g., CS = a flu-vaccine brand, US = sickness cue) in the absence of instructions. Across four studies examining the effects of aversive cues in ads promoting vaccine products, we find that using aversive cues can enhance attitudes towards a co-occurring vaccine brand even when there is no explicit instruction that directs people to assume a negational relation between co-occurring stimuli, reflecting the spontaneity of propositional evaluative learning. However, these positive effects of aversive cues on brand attitudes occurred only when people were under a low attentional load. When load was high, aversive cues were ineffective for enhancing (and even showed a more negative impact than neutral cues on) attitudes towards a vaccine brand, indicating the relative inefficiency of propositional learning of a negational relation.