Processing fluency: An inevitable side effect of evaluative conditioning

- The procedure of evaluative conditioning increases processing fluency of stimuli.
- The conditioned valence and the affectively positive fluency shape overall liking.
- The positive fluency experience amplifies the effect of positive conditioning.
- The positive fluency experience mitigates the effect of negative conditioning.
- Finding explains observed valence asymmetries and has implications for extinction.

Human preferences can be shaped by evaluative conditioning (EC), which describes observed changes in liking of an initially neutral stimulus (conditioned stimulus) due to repeated paired presentations with an inherently positive or negative stimulus (unconditioned stimulus). The experimental procedure of EC implies that participants are repeatedly exposed to the conditioned stimulus. Prior research suggests that repeated exposure to stimuli facilitates their processing. Furthermore, the resulting experience of processing fluency is known to shape human preferences through its inherent positive valence. Surprisingly, however, the role of processing fluency due to repeated stimulus exposure has never been directly investigated within the context of EC. The present research extends current conceptualizations of EC by incorporating processing fluency. In particular, it presents the first study that differentiates between a direct effect of stimulus pairing and a fluency-mediated effect of stimulus repetition on liking in a standard EC procedure. This approach helps to answer the open theoretical questions of why negative EC (i.e., EC applying negative unconditioned stimuli) tends to produce smaller effects than positive EC (i.e., EC applying positive unconditioned stimuli), and why positive EC is less susceptible to extinction than negative EC. On this basis, we strongly recommend considering processing fluency in theoretical models and empirical studies on EC and other forms of evaluative learning.