Stimulus–response learning and expected reward value enhance stimulus cognitive processing: An ERP study

Abstract

Reward affects our attention to stimuli, prioritizing those that lead to high‐value outcomes. Recently, it has been suggested that such reward‐related cognitive prioritization might be associated with the process of learning new stimulus–response (S‐R) associations, because both are acquired through extended reward training, and once established, they are hard to overcome. We used event‐related potentials (ERP) to analyze the contribution of S‐R links to the formation of reward‐related cognitive prioritization during reinforcement learning. Reward‐related cognitive prioritization was measured by comparing the ERP signals for stimuli predicting high‐value and low‐value outcomes. In addition, we compared a strong S‐R link (same stimulus, same response), with a weak S‐R link condition (same stimulus, two different responses). The participants’ performance was more accurate and faster when the procedure allowed for establishing strong S‐R links and for high‐value outcomes. Furthermore, those stimuli associated with strong S‐R links showed a larger P3 amplitude at parietal sites. Value effects (larger ERP activity for those stimuli predicting a high‐value outcome) were obtained at parietal and occipital sites in the P3 time window. However, value effects did not benefit from strong S‐R links in either the P1 or the P3 components. These results suggest that strong S‐R learning is not necessary to develop reward‐related modulations of ERP activity.

Model-free decision making resists improved instructions and is enhanced by stimulus-response associations

“…In other words, this manipulation triggered habitual processes, facilitating the association between specific stimuli and specific motor commands. In agreement with our results, using a different task, but manipulating the consistency of response mappings, Molinero et al (2021) found that reward-related cognitive prioritization was stronger when a constant response pattern was kept. Also, Hardwick, Forrence, Krakauer & Haith (2019) found that habits were produced when specific S-R associations were always executed with the same motor command.…”

“…In their version of the two-stage task, da Silva & Hare (2020) used first- and second-stage options that randomly swapped sides from trial to trial. This aspect of the procedure may prevent the formation of strong associations between these stimuli and specific motor commands (Molinero et al, 2021; Verleger et al, 2016, 2018). This is an aspect that may hinder the execution of habitual responses.…”

Is the habit system altered in individuals with obesity? A systematic review

“…In contrast, it seems that the model-free component of these models can be capturing the formation of incorrect models, rather than the operation of the habit system (da Silva and Hare, 2020). Thus, the standard two-step sequentialdecision task may not be sensitive enough to capture key processes involved in outcomeinsensitive habits, perhaps because participants have to choose between multiple outcomes with varying reward rates (Molinero et al, 2021;Wood and Rünger, 2016).…”

The P300 wave is decomposed into components reflecting response selection and automatic reactivation of stimulus–response links

“…The first hypothetical operation is associated with the reactivation of the established S‐R links (Verleger, 2020). Recent experimental investigations have explicitly tested the reflection of S‐R links in the target P3 waves demonstrating that stronger S‐R links elicit larger P3 amplitude (Molinero et al., 2021; Verleger, 2020). The second hypothetical operation is related to the allocation of perceptual and/or attentional resources (McCarthy & Donchin, 1981).…”

“…Based on the S‐R hypothesis (Molinero et al., 2021; Verleger, 2020), we hypothesize that at least one of P3 subcomponents is closely associated with the strength of S‐R links. Moreover, following the action selection hypothesis (Hillyard & Kutas, 1983; Pritchard et al., 1999) we speculate that at least one of the extracted components is closely associated with GO/NOGO responses.…”