Basic Processes Involved in Organization of Semantic Knowledge

• In Event: The Development of Memory Organization: Converging Insight From Multiple Perspectives

Abstract

The contents of our memories are vast. We have a wealth of episodic memories as well as a warehouse full of world knowledge (semantic memories). Both memory types accumulate over time. Yet semantic memory in particular is not organized temporally but in terms of related facts and concepts. This presentation describes research that informs how facts come to be organized in this way, even when that is not how they were experienced.

To illustrate the challenge—consider that at an aquarium, you learn “dolphins talk by clicking and squeaking.” Later, reading a book, you learn “dolphins live in groups called pods.” The facts were learned at different times yet for knowledge of dolphins to accumulate, they must be integrated with one another. Our research informs the basic processes in this manner of organization: reactivation of an earlier episode upon experience of a related episode, and integration of them. The outcome of these processes is revealed through self-derivation of new knowledge based on the integrated representation: pods talk by clicking and squeaking.

Study 1: The basic process of integration occurs when Episodes 1 and 2 (aquarium and book) are brought into memory simultaneously and a new, overlapping representation is formed. Using eye-gaze, we tested integration in 7-9-year-old children and adults. As in Figure 1, participants learned Fact 1 accompanied by two images (AB). After a buffer, they learned Fact 2 with two images, one overlapping with Fact 1 (BC). They then were shown one of the non-overlapping images (A) and given the option of looking at the related image (C) vs. distractors. Longer looking at the related image indicates integration. On trials on which they subsequently self-derived new knowledge, both groups integrated Facts 1 and 2. Self-derivation was strongly associated with eye-gaze indications of integration (OR=7.00 and 13.66, for adults and children, respectively; Bauer et al. in press).

Study 2: Preliminary to integration is the basic process of reactivation, which occurs when Episode 1 is brought into memory upon experience of related Episode 2, based on overlapping elements (dolphins). Using eye-gaze, we tested reactivation in 7-9-year-olds and adults. As in Figure 2, participants learned Fact 1 accompanied by a single image (B). After a buffer, they learned Fact 2 accompanied by a pair of images, one overlapping Fact 1 (BC). Immediately thereafter, they were given the option of looking at the previously unseen image associated with Fact 1 (A) vs. distractors. Longer looking at the image from Fact 1 is indicative of its reactivation. On trials on which they subsequently self-derived new knowledge, both groups reactivated Fact 1 upon experience of Fact 2. Self-derivation was strongly associated with eye-gaze indications of reactivation (OR=4.09); the relation was stronger for adults than children (OR=3.45; Miller et al. 2020).

These studies illustrate developmental differences in the likelihood of reactivation and integration, basic processes involved in the organization of semantic knowledge. They provide insights into how information experienced serially gets organized in terms of related facts and concepts.

Author

• Patricia J Bauer, Emory University
  Presenting Author