Chunking: the critical role of information compression in cognition – CHUNKED

Information compression is an essential aspect of memory and a fundamental building block of cognition. The goal of the present project is to study a crucial cognitive mechanism called chunking, which is a critical ingredient of short-term and long-term memory optimization. This project is twofold: the first part is related to implicit chunking, which shapes our perceptual systems by extracting the statistical regularities that are present in our environment, and the second part focuses on explicit chunking, which helps re-encoding information.

It is generally accepted that individuals have a tendency to group information in order to make it easier to retain by recoding it in chunks. The process of chunking allows the simplification of a memory task by taking advantage of regularities in order to reduce the quantity of information to retain. Chunking using long-term memory is usually thought as an example of an unwanted artifact in memory experiments. Accordingly, most memory span tasks use controlled material to prohibit the processing of the to-be-stored items as chunks. The current project takes an opposite direction, by inviting participants in our experiments to chunk. We developed a series of tasks designed to assess immediate memory capacity, while measuring the compressibility of information likely to allow the formation of chunks. Half of the present project is based on the idea that explicit chunking abilities directly impact individual differences in storage capacity because chunking is an optimization process of storage capacity in immediate memory. Accordingly, we believe that this new paradigm can shake up how the storage and processing components in working memory are conceptualized, and we think it can also potentially offer a better account of memory development and intelligence.

A second goal is to better identify the fundamental principles underpinning the creation of chunks in long-term memory. We think that data compression is a key idea to study the nonsupervised segmentation of complex material. Effectively, chunking is also considered as an implicit key learning mechanism and it has had considerable impact on the study of the structuration of our perceptual and linguistic systems. Since the seminal study by Saffran, Aslin and Newport (1996), several empirical reports have shown that humans (and nonhuman primates) have an innate ability to extract and code the regularities of their environment. Regularities correspond for instance to the repeated co-occurrence of two sources of information A and B. It has been proposed that the systematic co-occurrence of A and B leads to the implicit grouping of these pieces of information. Several theoretical explanations for these results have been proposed so far and chunking frequently appears as a key process in accounting for the empirical evidence. It has also been shown recently that the ability to extract regularities (by chunking) directly impacts individual differences in learning capacity. In these implicit learning situations where transitional probability learning occurs, chunks reflect the statistical regularities of the material to-be-learned and our hypothesis is that implicit chunking can also be studied as an optimization process based on data compression.

The main goal of the present project is to gain a better understanding of these crucial perceptual and conceptual cognitive processes that operate as information compression devices, on the basis of real data collected in human adults, children and nonhuman primates. We also plan on showing that the explicit encoding of information in immediate memory can be detrimental to implicit learning, because attentional processes can be directed away. The central idea of this experimental and modeling project is that chunking is a fundamental cognitive process by which perceptual and conceptual information can be compressed to form rich permanent (or temporary) memory structures.