Temporal expectations mediated the repetition effect in a sequence in two ways.

The repetition priming effect generally refers to facilitated responding in instances where the same stimulus or a very similar stimulus repeats after an initial occurrence. Prior studies showed that the repetition priming effect was greater when repetitive stimuli appeared at expected times than when they appeared at less expected times. However, in addition to the expectation for repetition, the expectation for nonrepetitive stimuli may also arise in a sequence, especially after repetitive stimuli continuously appeared several times. This study was designed to further reveal how these two kinds of expectations influence the repetition effect in a sequence. Participants were asked to solve 3, 4 or 5 repetitive tasks followed by a novel task in the experimental group, a situation where the expectations for repetitive events arise in the first three serial positions but that for nonrepetitive events arise in the fourth, fifth and sixth serial positions, or were asked to continuously solve 3-5 repetitive tasks in the control group, a situation where only the expectation for repetitive events appears. The results showed that the repetition effect appeared steadily in the whole sequence for the control group, whereas the repetition effect appeared in the early serial positions but was reduced in the later serial position for the experimental group. The findings revealed the dual influences of temporal expectations on repetition effects in a sequence.

Cognitive control of invalid predominant ideas in insight-like problem solving.

Predominant ordinary ideas are insufficient for solving insight-like problems; they interfere with subordinate original ideas and can produce a mental impasse. However, how people monitor and control invalid predominant ideas remains largely unknown. In the current study, participants were asked to solve a sequence of several similar practice problems that had the same solution to strengthen a predominant idea; the participants were then presented with an insight-like test problem that could not be solved by the predominant idea. The results showed that if the test problem was similar to the practice problems in which the predominant idea could typically be applied, it elicited greater late sustained potential (LSP) over the whole brain but no conflict-related N2 or N400 components, which suggests that the participants did not experience cognitive conflict and continued to verify the predominant but currently invalid idea. When the test problem differed from the practice problems, the items that participants reported trying to solve elicited greater N2-N400 and LSP over the whole brain, which suggests that the participants experienced cognitive conflict and exerted more reactive control over the invalid predominant idea; in contrast, the items that participants reported thinking about how to solve did not evoke greater conflict-related N2-N400 components and evoked even lower LSP, which likely indicates an ineffective state. These findings demonstrate three kinds of cognitive control toward invalid predominant ideas in situations where they are typically and not typically applied and provide empirical evidence of a mental impasse in insight-like problem-solving behaviors.

Expectations Attenuate the Negative Influence of Neural Adaptation on the Processing of Novel Stimuli: ERP Evidence.

When processing repeated stimuli, the neural response is attenuated (i.e., neural adaptation) and performance seems to be facilitated; however, this neural adaptation negatively influences the subsequent processing of novel stimuli. The present study was designed to test whether and how temporal expectations reduce neural adaptation and attenuate the negative influence of neural adaptation on subsequent novel problem solving. Temporal expectations were experimentally manipulated by asking participants to solve a novel problem following three to five repeated problems, generating the expectation of repeated events in the first three serial positions as well as that of novel events in the fourth to sixth serial positions. Compared to the first occurrence, repeated problems evoked more negative deflections, including greater N1, lower P2 and greater LNC amplitudes, regardless of whether participants expected a repeated or novel event; however, the mean amplitudes of the P2 and LNC were smaller in the latter condition. These results show neural adaptation during processing of repeated stimuli and demonstrate that neural adaptation is reduced when a novel event is expected. Regarding the novel events, the conflict monitoring- and resolution-related N400, P600 and LNC amplitudes decreased with decreased neural adaptation. These results indicate that the expectation of novel events attenuate the negative influence of neural adaptation on the subsequent processing of novel events. This study provides new insight into alleviating the constraints imposed by frequently used knowledge on the processing of novel stimuli.