Effects of sequential and non-sequential presentation conditions of multiple-stem facts on memory integration and cognitive resource allocation.

What limits the self-generation of new knowledge in the memory integration process? One striking contender is the amount of necessary pieces of information that are dispersed. Specifically, when essential information is scattered across multiple sources/places, it becomes challenging to effectively integrate and generate new knowledge. Most of the studies on memory integration have focused on the study of paired stem facts, but have neglected the exploration of multiple-stem facts. The present study examined college students' performance on memory integration under different conditions of three stem facts. In Experiment 1, participants were exposed to a series of novel, authentic stem facts in which every three relevant ones could be integrated to generate new knowledge. The results of Experiment 1 found that college students could spontaneously generate a new piece of information by integrating two or three separate but related facts. The integration can occur in at least two distinct types due to the different presentation orders of the learning materials: sequential recursive integration and non-recursive integration. College students performed better in sequential recursive integration than in non-sequential recursive integration, and this difference in integration performance is not caused by differences in memory for the stem facts. Based on Experiment 1, Experiment 2 used eye-tracking technology to explore the allocation of internal cognitive resources across different conditions of three stem facts. We found that in non-sequential recursive integration, college students had the longest visual duration and the highest number of fixations on the second stem fact. In sequential recursive integration, there were no other significant differences in the number and duration of visual fixations for the three stem facts. College students paid longer fixations to the second stem fact and the third stem fact in the non-sequential recursive condition than in the sequential recursive condition. Our study suggests that when information is related but cannot be integrated, longer fixation indicates stumbling when dealing with an unresolvable difficulty. When knowledge is presented in a stepwise manner (such as in the sequential recursive integration condition), it results in better semantic memory extension.