Posted May 25, 2008

The Construct Validity of Memory Span as a Measure of Intelligence

A Presentation at the North Carolina Cognition Conference

Chapel Hill, NC

March 2007

Bruce L. Bachelder, PhD

Independent Practice of Psychology, Retired

Morganton, NC 28655


Presentation Slides


One point of view in working memory research is that memory span measures merely storage, not intelligence. That interpretation, however, is challenged by a century of research data and intelligence assessment. Limited storage capacity is only one of several interpretations of memory span  (Bachelder, 2005). Memory span is more closely related to intelligence than is commonly thought (Bachelder & Denny, 1977a, b; Jensen, 1970). As a measure of intelligence, memory span has poor face validity, but excellent construct validity.

This presentation:
(1) summarized competing interpretations of memory span as due to a limit on storage, attention, or the ability to cope with span load (“complex stimulus control”);
(2) reviewed the psychometric concepts of face and construct validity;
(3) presented the empirical features of memory span which parallel the characteristics of intelligence; and
(4) discussed how a prominent point of view could conflict so sharply with a century of data and practice.


Bachelder, B. L. (2005). The spans question: Challenges to the memory interpretation of the "memory" span test. Paper presented at the Annual North
    Carolina Cognition Conference.
Bachelder, B. L. and Denny, M. R. (1977). A theory of intelligence: I. Span and the complexity of stimulus control. Intelligence, 1(2), 127-150.
Bachelder, B. L. and Denny, M. R. (1977). A theory of intelligence: II. The role of span in a variety of intellectual tasks. Intelligence, 1(3), 237-256.
Jensen, A. R. (1970). A theory of primary and secondary familial mental retardation. In N. R. Ellis. (Ed.), International review of research in mental
    retardation. New York, Academic Press.