The influence of element type and crossed relation on the difficulty of chunk decomposition

The involvement of decomposition and composition processes in restructuring during problem solving

Decomposition of chunks has been widely accepted as a critical proxy of restructuring, but the role of composition in forming new representations has been largely neglected. This study aims to investigate the roles of both decomposition and composition processes in chunk restructuring, as well as their relationships with "aha" experiences during problem-solving. Participants were asked to move a part of a character to another character to create two new characters. Across three experiments, the characters to be decomposed or composed were varied in terms of tight or loose chunks. The results showed that decomposition or composition of tight chunks led to lower success rates, longer response times, and significantly stronger "Aha!" emotional experiences (mainly in terms of surprise and suddenness). This study provides evidence for the contribution of both decomposition and composition processes to restructuring in creative insight.

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.

Left-hemispheric predominance on appropriateness evaluation of restructuring during chunk decomposition problem solving

Restructuring refers to achieving satisfactory solutions by breaking obstacles or forming novel associations in problem-solving. One critical question arises regarding how an appropriate solution is processed in our brain during the restructuring of problem representations. This study aims to explore the electrophysiological correlates of appropriateness evaluation of restructuring by employing a chunk decomposition task. During loose or tight chunk decomposition, participants needed to assess whether they could get a valid solution after probe removal from a source character chunk. As reflected by the late positive complex, the processing of appropriateness exhibited the greatest effect (appropriate vs. inappropriate) in left parietal regions for tight chunk decomposition, but exhibited insignificant differences across most brain regions for loose chunk decomposition. This study provides the first primary electrophysiological evidence that both hemispheres contribute to and the left hemisphere plays a predominant role in evaluating the appropriateness of restructuring in problem solving.

The late parietal event-related potential component is hierarchically sensitive to chunk tightness during chunk decomposition

The current study analyzed event-related potentials (ERPs) associated with visuo-spatial transformation in order to examine how "chunk tightness" affects the difficulty of chunk decomposition problems. Participants completed a Chinese character decomposition task in three conditions according to the tightness of the to-be-decomposed chunk (tight vs. medium vs. loose). Behavioral data showed that performance became worse (longer reaction time, lower accuracy) as chunk tightness increased. ERP data showed that, as chunk tightness increased, the LPC exhibited a significant decrease at posterior electrode sites. The results indicate that chunk tightness might exert its primary effect on chunk decomposition difficulty by increasing the difficulty of visuo-spatial transformation, a process linked to the parietal LPC.

Unconditional Perseveration of the Short-Term Mental Set in Chunk Decomposition

A mental set generally refers to the brain's tendency to stick with the most familiar solution to a problem and stubbornly ignore alternatives. This tendency is likely driven by previous knowledge (the long-term mental set) or is a temporary by-product of procedural learning (the short-term mental set). A similar problem situation is considered the factor required for perseveration of the long-term mental set, which may not be essential for the short-term mental set. To reveal the boundary conditions for perseveration of the short-term mental set, this study adopted a Chinese character decomposition task. Participants were asked to perform a practice problem that could be solved by a familiar loose chunk decomposition (loose solution) followed by a test problem, or they were asked to repeatedly perform 5-8practice problems followed by a test problem; the former is the base-set condition, and the latter is the enhanced-set condition. In Experiment 1, the test problem situation appeared to be similar to the practice problem and could be solved using the reinforced loose solution and also an unfamiliar tight chunk decomposition (tight solution) (a 2-solution problem). In Experiment 2, the test problem situation differed from the practice problem and could only be solved using an unfamiliar tight solution (a 1-solution problem). The results showed that, when comparing the enhanced-set and base-set conditions, both the accuracy rate and the response times for solving the test problem with a tight solution were worse in Experiment 1, whereas the response times were worse in Experiment 2. We concluded that perseveration of the short-term mental set was independent of the similarity between problem situations and discuss the differences in perseveration between two types of fixation.