Relevance acquisition through motivational incentives: Modeling the time-course of associative learning and the role of visual features.

Motivational relevance associated with symbolic stimuli impacts both neural and behavioral responses, similar to visual stimuli with inherent emotional valence. However, the specific effects of associated relevance on early sensory stages and lexico-semantic processing of these stimuli remain unclear, particularly considering the role of low-level visual features in relevance acquisition. To address these issues, we employed an associative learning paradigm in which we manipulated visual features, but not the stimuli themselves. The study (N = 48) included a learning phase, where pseudowords were associated with either gain, loss, or neutral outcomes. This was followed by a test phase the next day, involving an old/new decision task, in which stimuli were presented in either the same or a different font. During both phases, pupil responses and event-related brain potentials (P1, Early Posterior Negativity (EPN), Late Positive Complex (LPC), P3) were measured. Stronger pupil responses and increased neural activation in early visual encoding (P1) and lexico-semantic processing (EPN) were observed during relevance acquisition, particularly for loss associations. After relevance acquisition, the most substantial effect on modulating lexico-semantic processing was observed for gain associations, as evidenced by both behavioral responses and neural activity. During the test phase, exposure to incongruent visual features of the stimuli influenced the same processes that were observed during relevance acquisition. Notably, these effects of visual feature congruence were independent of those of associated motivational relevance. These results highlight the dynamic nature of motivational relevance effects, revealing differential effects observed during acquisition and the test phase, as well as between earlier perceptual processing and later neural and behavioral responses.