Sunday, May 31, 2026

Research Alert: Deary on Construct validity and intelligence differences: The murder board, the magic number, and the breadcrumb trail

Quick FYI email research alert post:  This is open access article.👍
 
Construct validity and intelligence differences: The murder board, the magic number, and the breadcrumb trail - ScienceDirect 
https://www.sciencedirect.com/science/article/pii/S0160289626000279?ref=cra_js_challenge&fr=RR-1
 
Abstract

In this piece there is a resume of some of the most-cited (though maybe less-than-closely-read) articles on construct validity, and a rediscovery that they articulate it in various ways, including destroying it. That moves on to considering: whether ideas about construct validity are different from/part of the philosophy of science; whether scientists generally and those, more specifically, working in intelligence, acquaint themselves with these ideas and guide their practice from having done so (and whether it matters if they don't); and whether the relationship between writers about construct validity/philosophy of science and empirical researchers is bite or bark (aka fire or smoke). Then, with attention to the construct/idea/field of individual differences in intelligence, there is an as-honest-as-introspection-affords account of what intelligence is like in this researcher's head: thus, the murder board, the magic number, and the breadcrumb trail. Conclusion: whereas intelligence test scores continue to accrue their impressive empirical regularities and its bio-, psycho-, and social- origins prove hard to divine, and whereas there will continue to be writings about construct validity, maybe most researchers in the field will continue to have their bespoke and more-or-less well-researched and -applied guardrails against bad science.
 
Select quotes:
 
“This preamble is by way of introducing that I thought it might be useful to try to put down how I represent—after more than 40 years of working on it—the construct validity of intelligence in my head. It's an idiographic approach, but it is intended to be an everyman account of the working- day utility that construct validity provides, including any personal wonkiness, vagueness, and inaccuracies.”
 
The best metaphor I have been able to think of for how intelligence- differences-research-is-represented-in-my-brain is the murder board that one sees in TV detective programmes—the rather corny board with photos and post-it notes and other scraps of paper and writing, linked with bits of red tape secured with pins. The metaphor is just a way of representing the kinds of evidence that, to date, have accrued about and afford interpretations of cognitive test scores. The missing centre of the murder board is the culprit, though it might have suspects. With intelligence's murder board, we might have a holding note at the centre of the board with ‘intelligence' written on it. But, don't be fooled, that does not mean it is a thing, like the DNA molecule. Rather, it is a holding term for the load of stuff that surrounds it. For now, let's assume that that note called intelligence means the total score from a diverse battery of cognitive tests that were administered in a standardised way. It's that score, without assumptions about it (some will be thinking that there are always assumptions). The stuff that surrounds the ‘intelligence test score' note at the centre of the board records the empirical regularities found in relation to those scores. We might form a circle round it with notes that summarise phenotypic information; listing just a few examples, we would note the discovery and replication that cognitive tests tend to correlate positively (Carroll, 1993), that different batteries of cognitive tests afford a general cognitive component/factor that ranks people similarly (Johnson et al., 2008), that intelligence has high test- retest reliability and high longitudinal stability (Deary, 2014), that there are well-replicated ageing patterns (which tell us that there is a useful distinction between fluid and crystallised intelligence) (T. A. Salthouse, 2009), and so forth. It's been said many times before, but it's worth stating that intelligence (cognitive test scores) arguably enjoys more and more-robust empirical regularities than maybe anything else in psychology. At the centre of the board, then, we have haloes of well-replicated empirical regularities that surround test scores on diverse types of cognitive capability. Intelligence is a holding term for this (the suspect).”
 
 

Pardon typos and spelling errors-Message may be sent from iPhone and I've always had spelling problems :)