The redundancy effect is related to a lack of conditioned inhibition: Evidence from a task in which excitation and inhibition are symmetrical

Rescorla and Wagner’s model of learning describes excitation and inhibition as symmetrical opposites. However, tasks used in human causal learning experiments, such as the allergist task, generally involve learning about cues leading to the presence or absence of the outcome, which may not reflect this assumption. This is important when considering learning effects which provide a challenge to this model, such as the redundancy effect. The redundancy effect describes higher causal ratings for the blocked cue X than for the uncorrelated cue Y in the design A+/AX+/BY+/CY–, the opposite pattern to that predicted by the Rescorla–Wagner model, which predicts higher associative strength for Y than for X. Crucially, this prediction depends on cue C gaining some inhibitory associative strength. In this article, we used a task in which cues could have independent inhibitory effects on the outcome, to investigate whether a lack of inhibition was related to the redundancy effect. In Experiment 1, inhibition for C was not detected in the allergist task, supporting this possibility. Three further experiments using the alternative task showed that a lack of inhibition was related to the redundancy effect: the redundancy effect was smaller when C was rated as inhibitory. Individual variation in the strength of inhibition for C also determined the size of the redundancy effect. Given that weak inhibition was detected in the alternative scenario but not in the allergist task, we recommend carefully choosing the type of task used to investigate associative learning phenomena, as it may influence results.

The redundancy effect in human causal learning: No evidence for changes in selective attention

Several recent papers have reported a difference in associative learning for two kinds of redundant cues, such that a blocked cue (e.g., X in A+ AX+) apparently forms a stronger association with the outcome than an uncorrelated cue (e.g., Y in BY+ CY-). This difference is referred to as the redundancy effect, and is of interest because it is contrary to the predictions of a number of popular learning models. One way of reconciling these models with the redundancy effect is to assume that the amount of attention paid to redundant cues changes as a result of experience, and that these changes in attention influence subsequent learning. Here, we present two experiments designed to evaluate this idea, in which we measured overt attention using an eye tracker while participants completed a learning task that elicited the redundancy effect. In both experiments, gaze duration was longer for uncorrelated cues than for blocked cues, but this difference disappeared when we divided gaze durations by trial durations. In Experiment 2, we failed to observe any difference in gaze duration when blocked and uncorrelated cues were subsequently presented together. While the observed difference in gaze duration for the two types of redundant cue may contribute to differences in learning during initial training, we suggest that the principal causes of the redundancy effect are likely to lie elsewhere.