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Expectations regarding future events enable preparatory processes and allow for faster responses to expected stimuli compared to unexpected stimuli. Expectations can have internal sources or follow external cues. While many studies on expectation effects use some form of cueing, a direct comparison with self-generated expectations involving behavioral and psychophysiological measures is lacking. In the present study we compare cue-induced expectations with self-generated expectations that are both expressed verbally in a within-subjects design, measuring behavioral performance, and event-related brain potentials (ERPs). Response time benefits for expected stimuli are much larger when expectations are self-generated as compared to externally cued. Increased amplitudes in both the N2 and P3 components for violations of self-generated expectations suggest that this advantage can at least partially be ascribed to greater perceptual preparation. This goes along with a missing benefit for stimuli matching the expected response only and is mirrored in the lateralized readiness potential (LRP). Taken together, behavioral and ERP findings indicate that self-generated expectations lead to increased premotoric preparation compared to cue-induced expectations. Underlying cognitive or neuronal functional differences between these types of expectation remain a subject for future studies.

The role of expectations in sequential adaptation to cognitive conflict has been debated controversially in prior studies. On the one hand, a sequential congruency effect (SCE) has been reported for trials in which participants expect a repetition of conflict level. On the other hand, conflict level expectations vs. the SCE have been shown to develop differentially across runs of trials with the same conflict level, arguing against the theory that the SCE is purely driven by expectation. The current verbal Stroop experiment addresses this controversy by two means. First, we tested which specific type of expectation (cue-induced expectations vs. self-generated predictions) might affect the SCE. Second, we assessed the impact of expectation on the SCE as well as the development of SCE and expectation with congruency level run length in one design. We observed a dissociation between expectations and SCE, demonstrating that the SCE is not exclusively driven by expectations. At the same time, we found evidence that (self-generated) expectations do have an impact on the SCE. Our data document especially high performance for one specific combination of task events: congruent trial accompanied by congruent prediction and conflict level repetition. Our results are in line with theories attributing conflict adaptation effects to the "adaption to the lack of conflict". We discuss our results in a broader context of theories about conflict monitoring.

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