Lynn (2010) suggests that differences in average intelligence explain many of the differences observed across the Italian regions. This paper puts forward a methodological critique to his study, coupling it with an empirical test showing that Lynn's analysis is not sufficiently robust to support its conclusions. (Contains 2 tables.)

Beraldo (2010) and Cornoldi, Belacchi, Giofre, Martini, and Tressoldi (2010) (CBGMT) have eight criticisms of my paper (Lynn, 2010) claiming that the large north-south differences in per capita income in Italy are attributable to differences in the average levels of intelligence in the populations. CBGMT give results for seven data sets for IQs in…

Working with data from the PISA study (OECD, 2007), Lynn (2010) has argued that individuals from South Italy average an IQ approximately 10 points lower than individuals from North Italy, and has gone on to put forward a series of conclusions on the relationship between average IQ, latitude, average stature, income, etc. The present paper…

Studies of group differences in intelligence often invite conclusions about groups in general from studies of group differences in selected populations. The same design is used in the study of group differences in other traits as well. Investigators observe samples from two groups (e.g. men and women) in some accessible population, but seek to…

The state of research on intelligence is reviewed in an editorial. The author notes conceptual, measurement, and data analysis problems. Suggestions as to how research on intelligence can be improved are provided. (RD)

Jensen has reported reaction-time (RT) studies indicating that various parameters correlate significantly with IQ. Two parameters of interest are slope of RT across set size and increasing correlations of RT with IQ as set size increases. After reviewing these studies, the author concludes that Jensen's claims are unwarranted. (Author/BW)

Research on the determinants of intelligence and factors that relate to variability in intellect are discussed. It is argued that studies in this area usually focus on individual determinants and rarely reflect the true nature of the processes through which variability in determinants relates to variability in intellectual development. (SLD)

The author replies to Jensen and Vernon's article and maintains that there is little reason for accepting Jensen's claims, particularly with respect to the major theoretical question. (Author/LMO)

Ruchalla, Schalt, and Vogel (1985) reported a negative correlation between the g-loadness of intelligence subtests and the extent to which the subtests correlated with reaction times. Possible methodological problems with Ruchalla et al. are described, and results of two other studies pertinent to the issue are discussed. (Author/LMO)

This paper examines Longstreth's criticisms of Jensen's studies relating reaction-time to measures of intelligence and finds them unconvincing. While Longstreth raises some interesting questions, the authors found no evidence in the data for practice or order effects in a reaction-time paradigm. (BS)

Four points are made in regard to the controversial reaction times studies: (1) apparatus used is not the best; (2) practice effects have not been thoroughly accounted for; (3) there is some evidence that simple reactions are different from choice ones; and (4) basic data to be explained are those which show substantial group differences.…

The present study points out problems in the model, indices of familiality, and design used by Benbow, Zonderman, and Stanley in a study of precocious children and their parents. (Author/LMO)

Data of Skodak and Skeels (1949) are reinterpreted to suggest that at least one-third of the reported advantage of adopted children's intelligence quotients (IQ) over adoptive mothers is an artifact of the IQ test norms. The children's mean IQ could easily be higher than the estimated figures usually quoted. (SLD)

Recent studies are examined for methodological adequacy in establishing dimensions of individual differences in information-processing abilities, and the theoretical problems involved in inferring psychological processes from individual difference dimensions. Methodological inadequacies include use of small samples, questionable procedures in…

Longstreth's critique of Jensen's research on the relationship of IQ to individual differences in visual reaction time (RT), measured in the Hick paradigm, is said to have numerous errors of fact and interpretation, some trivial and some of theoretical importance. (Author/LMO)