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This paper reports an investigation of whether data on intelligence obtained by speeded testing have to be represented in confirmatory factor analysis (CFA) by an additional factor besides the ability factor, and whether the additional factor can be identified as a speed factor. The paper further examined whether the hypothesized speed factor influences the relationship between intelligence and working memory. Two independent datasets including data obtained by speeded intelligence testing, measures of processing speed and of working memory were investigated by means of CFA. A hybrid bifactor model was employed to represent the hypothesized speed and the ability factor of the intelligence data. Whereas the factor loadings for representing ability were set free for estimation, the factor loadings for representing speed were constrained according to theory-based expectations. The results showed that a speed factor is necessary for achieving a good fit to the data with speeded testing. The convergent validity of the speed factor was shown by data on measures of processing speed. Furthermore, it turned out that the consideration of the latent speed factor led to a decrease of the correlation between intelligence and working memory. These results suggest that speeded testing influences the assessment of intelligence and may also bias empirical findings regarding the relationships between intelligence and other constructs.

times are still rarely reported in developmental psychology although they are an indicator of the neural maturity of children's information processing system. Competence and capacity are confounded in development, where children may be able to reason, or remember, but are unable to cope with information processing load. Furthermore, there are social implications in ignoring the speed factor. Slow and apparently delayed reactions from infants and children often try the patience of parents and teachers alike, and can be interpreted as non-compliance already before the child gets the chance to respond. Furthermore, individual differences in reaction times in young children are high, with standard deviations that may prevent significance of differences between task conditions. This inaugural article argues that reaction time research with children nevertheless can be done and raises the methodological problems involved. An example is presented that shows that challenges to capacity reveal true mental effort in a memory task when delay is controlled down to milliseconds rather than just in terms of the number of delay items.

Data from two studies that tested children’s attention using visual search for a series of targets in a complex display and a sustained attention task waiting for signals in a similar display were subjected to Factor Analysis to explore previous indications that speed and accuracy (the number of false alarms to non-targets) on this task reflect different mechanisms. The two factors identified confirmed the separation of these two measures and also suggested that the speed factor was related to Mental Age, while the accuracy factor was related to ratings of attentional ability. It is suggested that ratings of attentional ability reflect the efficiency of Executive Functions, displayed in the ability to inhibit responses to non-targets in these tasks, while speed of search is related to processing speed in the nervous system. Therefore Intelligence and Attentional Ability depend on different underlying features of the nervous system.

The present study explored the dimensionality of infant cognition by factor analyzing measures from a battery of tasks administered to a large cohort of 7-month-old preterm and full-term infants (N=203). A principal axis factor analysis yielded three factors accounting for 37% of the variance. There was one attention factor (look duration and shift rate), one speed factor (reaction time), and one memory factor (immediate recognition). The results indicate that infant cognition is better characterized as multidimensional than as unitary, and support the idea that many of the tasks used in infancy tap discrete elementary abilities.

Thirty male adolescent sex offenders and 20 age-matched male adolescents completed an extensive battery of attention and executive function tests. Controls were obtained from adolescents from a socially and economically deprived background, typical of the offending group. The attention battery was based on Mirksy, Anthony, Duncan, Ahearn, and Kellam (1991) and the executive function battery on Kelly (2000a). Successful matching for IQ was not achieved and therefore ANCOVA comparisons were made between the groups, with IQ as the covariate. In attention a highly significant difference was found on the focus-execute factor and a significant difference on the shift factor. In executive function there was a highly significant difference only on the response speed factor. In all cases better abilities were demonstrated by the control group. The importance of thorough neuropsychological investigation in the clinical assessment of this forensic group is supported. The clinical implications of neuropsychological deficits in terms of risk assessment and clinical management are discussed.

Four subtypes of Wechsler Intelligence Scale for Children-Third Edition (WISC-III) factor index score patterns were identified by means of two-stage cluster analysis in a sample of 153 children with traumatic head injury (THI). Three of these subtypes were differentiated primarily by level of performance, and bore close resemblance to clusters known to be prevalent in the WISC-III standardization sample. One subtype displayed an uncommon pattern of performance, characterized by selective impairment on the Perceptual Organization and Processing Speed factor indexes, which may be clinically significant in children with THI. Support for the reliability and validity of the subtypes is provided. It is concluded that the WISC-III is a useful tool in the evaluation of sequelae of THI in children.

Scores in ability tests administered to students in grades 4–9 were simultaneously factor-analyzed within twelve gender by grade groups. Gender and grade differences in means and variances were studied for five latent ability factors according to a hierarchical model and compared with means and variances in the observed scores. Girls had higher means than boys in a general ability factor (G), in a residual general speed factor (Gs′) and in a residual factor of numerical facility (N′). Boys were higher in a residual vocabulary factor (V′) and most of all in a residual spatial visualization factor (Vz′). Boys had larger variances than girls in N′ and Gs′. In general the differences in means and variances were in the same direction for the closest corresponding observed scores, but some striking discrepancies between latent and observed scores were found. As a rule, the discrepancies were due to the complexity of the tests where one factor could compensate for another. In the discussion it was pointed out that some of the differences found were likely to have changed between the testing in the late 1950s and the present. Nevertheless the demonstration of the divergence between analyses of latent vs. observed scores remains valid.

The primary intent of this research was to determine whether the Processing Speed Factor scores of the WISC-III would distinguish between groups of clinically referred children. A total of 311 elementary, junior high, and senior high students were grouped according to ADHD, VMI, behavioral, low academic achievement categories, and physical health problems or absence of such problems. Multiple comparisons using the Newman-Keuls and multiple regression techniques indicated that processing speed was a significant diagnostic factor differing between clinical groups. Anderson's (1992) model of the cognitive architecture of the mind was used to explain the specfic findings.

Speed of responding in different domains (handwriting, coding, naming, and simple text reading) was compared in two samples of adolescents with learning disabilities. In both samples, speed measures were significantly interrelated. Slowness was more characteristic of students with generalized basic skill deficits (reading, spelling, and arithmetic) than of those with single achievement deficits. Phonological decoding skill and naming speed (sample 2 only) were not correlated. Poor decoders were poor word list readers, whether or not slow namers, whereas slow namers were poor in arithmetic and were slow readers, whether or not poor decoders. The relation between slow naming/reading and weakness in arithmetical calculation merits further study in learning-disabled students. It is suggested that slowness impedes automatization in reading, spelling, and arithmetic.

This study investigated the effects of age on a random generation task. In Experiment 1, young and elderly subjects were asked to generate random strings of letters at 1-, 2-, and 4-s rates. The elderly subjects produced more alphabetical stereotype responses than young subjects, even in the slowest rate condition. Furthermore, as faster rates were imposed, elderly subjects could no longer maintain the pace and missed responses. In Experiment 2, subjects were required to generate letters at the same time that they sorted cards into one, two, four, or eight categories. Age-related differences were observed on most of the measures of randomness (stereotypes, zero-order, and first-order measures). In addition, the number of errors increased with the number of sorting alternatives, especially for elderly subjects. These results suggest the existence of a reduction of the central executive resources, along with a reduced inhibition ability, in the elderly subjects. However, the contribution of a perceptual speed factor is also discussed. (C) 1998 Academic Press.

The question of an association between IQ and measures of timed performance derived from inspection time and reaction time was examined in a sample of 182 adults and by reanalyzing data involving 48 adults from a previously published study. Multiple regression analysis found that measures of timed performance accounted for as much as 25% of IQ variance in the normal population, but that the inclusion of borderline and mildly retarded subjects resulted in much higher correlation coefficients because of the markedly less efficient performance of these persons in tasks of this kind. This outcome raised doubts about the validity of combining data from retarded and nonretarded subjects. Results ran counter to claims that tasks of the kind used are largely uninfluenced by cognitive variables, so that findings are not necessarily explained satisfactorily in terms of a mental speed factor. It was concluded that these measures of timed performance do not, at this time, provide a basis from which a reliable culture-fair measure of intelligence might be devised.

One hundred and thirteen high school students were randomly assigned to one of two groups that were administered an intelligence test (the Multidimensional Aptitude Battery) under either timed or untimed conditions. Subsequently, all subjects were given a battery of 8 reaction time tests. Multiple regression analyses showed that combinations of RTs were approximately equally good predictors of IQ scores in both groups. Zero-order correlations between each RT test and IQ scores were also approximately equal for timed and untimed Verbal and Full-Scale scores but correlations with Performance scores were higher in the timed condition. The extent to which the different RT tests correlated with timed scores was quite highly related to the tests' loadings on a general speed factor but these loadings were not related to the tests' correlations with untimed scores. Rather, the relative complexity of the RT tests had a stronger influence on their correlations with IQ scores in the untimed condition. It is concluded that timed and untimed intelligence tests impose different information-processing demands on subjects but that the speed with which subjects can cope with these demands is equally important in both conditions.

In an experimental study with 40 English-German and 40 German-Swedish bilingual high school students, automaticity and interference were analyzed on the basis of Shiffrin and Schneider's theory of controlled and automatic processing. Confirming the assumptions inferred from the theory, dominant bilinguals reacted significantly faster to pictured objects in their dominant language than did balanced bilinguals in either of their two languages. Interaction effects with frequency indicated less experience with rare words in the balanced groups. Matched on the basis of reaction time scores, the balanced groups continued to show a higher error rate in recall, but not in recognition when compared with the dominant groups. It was concluded that training alone could not account for the differences in recall. A congenitally determined mental speed factor was suggested for which the theory makes no direct commitment. The strong interrelation between automaticity and interference was shown; their significance for bilinguals in highly speeded and unstructured tasks was also shown. The results reveal high cross-cultural consistency.

Werdelin, I. & Stjernberg, G. On the nature of the perceptual speed factor. Scand. J. Psychol., 1969, 10, 185–192.–149 subjects, about 15 years old, were given 25 psychological tests. Some of these defined the reference factors R, S, N, and P, others were designed to study the nature of the P factor. It was found that certain visual tests showed successively higher loadings in the P and N factors the more they were practiced. This effect of practice is probably restricted to tests of a certain kind. Very simple visual tests showed high loadings in the P factor. Hypotheses as to the nature of the P factor are suggested.