What is working memory capacity, and how can we measure it?

Oliver Wilhelm,Klaus Oberauer,Andrea Hildebrandt

doi:10.3389/fpsyg.2013.00433

Abstract

A latent variable study examined whether different classes of working-memory tasks measure the same general construct of working-memory capacity (WMC). Data from 270 subjects were used to examine the relationship between Binding, Updating, Recall-N-back, and Complex Span tasks, and the relations of WMC with secondary memory measures, indicators of cognitive control from two response-conflict paradigms (Simon task and Eriksen flanker task), and fluid intelligence. Confirmatory factor analyses support the concept of a general WMC factor. Results from structural-equation modeling show negligible relations of WMC with response-conflict resolution, and very strong relations of WMC with secondary memory and fluid intelligence. The findings support the hypothesis that individual differences in WMC reflect the ability to build, maintain and update arbitrary bindings.

Highlights

In the first section we investigate the scope of the working-memory capacity (WMC) construct and show that WMC encompasses both complex-span and updating tasks
In the final section we investigate the relation of WMC and secondary memory (SM) to fluid intelligence
WORKING MEMORY CAPACITY AND SECONDARY MEMORY We address the relation between the general WMC factor established in Model 2 and SM

Summary

METHODS

In the verbal RNb task, letters were presented one by one in 1 to 3 boxes, depending on the load level of the trial; see Table A1 for details. In the letter-color binding task, each trial involved sequential presentation of a short list of letter-color pairs that participants had to remember. This was followed immediately by a recall test, probing each pair in a random order. In a second step of initial data screening, we estimated a confirmatory factor model for the core constructs investigated in the present study and inspected Mahalanobis distances of participants as a measure of deviance in the multivariate distribution. Regardless of sample size the CFI values should be 0.95 or higher, RMSEA values should be 0.06 or smaller, and SRMR values should be 0.08 or smaller (Hu and Bentler, 1995)

RESULTS

DISCUSSION

CONCLUSIONS