Effects of induced chunking on temporal aspects of serial recitation.

Abstract

Ss learned serial lists composed of random orders of 24 letters of the English alphabet. The main independent variable was stimulus grouping, where the letters were presented either 1, 3, 4, 6, or 8 letters at a time. After reaching the criterion of 1 perfect recitation, Ss were required to recite the serial list backward. Time intervals between the letters during the criterion and backward recitations were analyzed to show the induced chunking produced by the stimulus grouping.

Functional Coupling of Human Prefrontal and Premotor Areas during Cognitive Manipulation

“…From another perspective, both types of recognition may involve attentional selection to a certain extent (Miller, 1999;Rowe et al, 2000;Rowe and Passingham, 2001). However, ACROSS recognition requires more demanding selection than WITHIN recognition because the central executive needs not only to identify the chunk labels but also to select chunk contents (McLean and Gregg, 1967;Ericcson et al, 1980). Therefore, the main effects of recognition (ACROSS minus WITHIN) were hypothesized to reflect cognitive costs for the segmenting operation.…”

“…The subjects were allowed to participate in fMRI experiments only after confirmation of immediate and perfect recitation of all of the standard sequences and SUPs. Based on previous evidence (McLean and Gregg, 1967), the six standard sequences were hypothesized to form distinct chunks, each consisting of four codes. Strong association among these four codes was the first prerequisite of the experiment.…”

“…The present study was designed so that chunk structures within LTM influenced cognitive manipulation of WM items. Therefore, before the imaging experiment, the formation of hierarchical chunks was experimentally controlled through learning (McLean and Gregg, 1967). All of the subjects underwent a two-staged training session for a period of 2 months.…”

“…Attentional selection is required in both WITHIN and ACROSS recognition conditions, in that subjects must select a four-code sequence from an eight-code sequence maintained within memory buffer. However, the ACROSS recognition would cost higher load than the WITHIN recognition, because it should be difficult for the central executive to directly retrieve a segment crossing a chunk boundary (McLean and Gregg, 1967;Ericcson et al, 1980). The DLPFC has been associated with high-level executive processes (Miller, 1999).…”

“…The hierarchical structure prevents the central executive from retrieving elements crossing a chunk boundary directly. To do so, subjects first located the chunks to which the elements belonged and then recited the entire chunks or further examined their contents (McLean and Gregg, 1967;Ericcson et al, 1980). These stepwise procedures should induce temporary reorganization of chunk representations within WM.…”