g (general intelligence) is a hot topic

It is interesting that during the past week (on the IAP CHC listerv) there has been an extended thread regarding the construct of g (general intelligence) and how it is operationalized in different intelligence batteries (click here for post re: this thread and a link to an important set of comments made by John Horn in 1999).

Today there has also been a focus on g on the NASP listserv, this thread dealing with the often reported finding that Gf maybe isomporphic with g.

Given the above, I realized that I've been remiss in reminding people of John "Jack" Carroll's final thoughts regarding the Gf-g relationship and Horn's anti-g position.

Jack's last formal publication (2003) was his chapter (The higher-stratum structure of cognitive abilities: Current evidence supports g and about ten broad factors) in Helmuth Nyborg (Ed.), The scientific study of general intelligence: Tribute to Arthur R. Jensen. Elsevier Science/Pergamon Press. In this chapter he analyzed various correlations matrices from the WJ-R.

Before his death and the publication of this chapter, Jack Carroll distributed a pre-publication copy of his chapter and allowed me to post it to the IAPCHC listserv archive folders. I'm now (click here) providing a link to a copy of the pre-pub draft for readers who do not have copies of Nyborg's text.

Of interest to the recent listserv threads are the following g-related comments by Jack Carroll (emphasis in italic added by this blogmaster). I do not pretend to speak for Dr. Carroll, but his last publishedchapter provides fairly specific statements regarding his g-thoughts at the time.

• "The results show that there is indeed a factor Gf (Fluid Reasoning) that is significantly separate and different from factor g, tending to disconfirm any view that Gf is identical to g."(p. 11 of pdf pre-pub chapter).

• Horn's comment suggests that he conveniently forgets a fundamental principle on which factor analysis is based (a principle of which he is undoubtedly aware)--that the nature of a single factor discovered to account for a table of intercorrelations does not necessarily relate to special characteristics of the variables involved in the correlation matrix; it relates only to characteristics or underlying measurements (latent variables) that are common to those variables. I cannot regard Horn's comment as a sound basis for denying the existence of afactor g, yet he succeeded in persuading himself and many others to do exactly this for an extended period of years." P.16-17 of pdf pre-pub chapter).