The secular rise in IQs in the Netherlands: Is the Flynn effect on g?

IQ scores have been increasing over the last half century, a phenomenon known as the Flynn effect. In this study, we focused on the question to what extent these secular gains are on the g factor. Two IQ batteries: the Interest-School achievement-Intelligence Test (ISI) and the Groningen Final Examination Primary Education (GALO) yielded small and modest negative correlations between standardized gains and g loadings. As these studies employ large samples this suggests that the combined literature now shows a modest negative relationship between d (the secular change in test score) and g.     

White–black differences in g and non-g effects for the SAT and ACT

This research examined g and non-g effects for the SAT and ACT for whites and blacks. SAT scores, ACT scores, and college GPAs were obtained from the National Longitudinal Survey of Youth. g was estimated using the Armed Services Vocational Aptitude Battery. Results indicated that (a) the g loadings of SAT and ACT composite scores were lower for whites than blacks, (b) group differences in the g loadings were related to the math subtests of the SAT and ACT, and (c) non-g variance accounted for surprisingly large percentages of SAT–GPA and ACT–GPA relations (range = 37–67%). The findings are discussed in terms of Spearman’s Law of Diminishing Returns.     

Are adoption gains on the g factor? A meta-analysis

When children are adopted into prosperous families they generally show IQ gains. The meta-analytic correlation between subtest g loadings and adoption gains is examined (K = 4, combined N = 3018). A number of meta-analytic corrections are applied to the estimate, yielding a correlation of −1. The results are discussed.     

Who discovered the Flynn effect? A review of early studies of the secular increase of intelligence

Flynn has been credited with having discovered the increase in IQs that has been reported in a number of countries during most of the twentieth century and that has come to be known as “the Flynn effect”. This paper documents and discusses a number of reports of increases in IQs that were published from 1936 onwards before the phenomenon was rediscovered by  and . These early reports showed that the Flynn effect is fully present in pre-school children, does not increase during the school age years, and is greater for non-verbal abilities than for verbal abilities.     

Phonological recoding: Is the regularity effect consistent?

An attempt was made to distinguish between the dual-access and the activation and synthesis models of word identification. Word regularity and consistency were factorially manipulated. In two experiments lexical decisions were required, and in two the task was word naming. Within each task, comparisons were made of the effects achieved by manipulating the degree to which subjects were free to rely on a phonological, rather than a visual, stimulus code. The results suggested that lexical access generally involves the activation of lexical entries that are visually similar to the target, but that subjects do favor a phonological code when the task requires the naming of words only. The data were interpreted as requiring a model incorporating elements of both the dual-access and the activation and synthesis frameworks.     

Adaptive memory: Is the animacy effect on memory due to emotional arousal?

Animate entities are often better remembered than inanimate ones. The proximal mechanisms underlying this animacy effect on recall are unclear. In two experiments, we tested whether the animacy effect is due to emotional arousal. Experiment 1 revealed that translations of the animate words used in the pioneering study of Nairne et al. (Psychological science, 24, 2099–2105, 2013) were perceived as being more arousing than translations of the inanimate words, suggesting that animacy might have been confounded with arousal in previous studies. In Experiment 2, new word lists were created in which the animate and inanimate words were matched on arousal (amongst several other dimensions), and participants were required to reproduce the animate and inanimate words in a free recall task. There was a tendency towards better memory for arousing items, but robust animacy effects were obtained even though animate and inanimate words were matched on arousal. Thus, while arousal may contribute to the animacy effect when it is not carefully controlled for, it cannot explain the memory advantage of animate items.     

Is the picture bizarreness effect a generation effect?

Bizarre stimuli usually facilitate recall compared to common stimuli. This investigation explored the so-called bizarreness effect in free recall by using 80 simple line drawings of common objects (common vs bizarre). 64 subjects participated with 16 subjects in each group. Half of the subjects received learning instructions and the other half rated the bizarreness of each drawing. Moreover, drawings were presented either alone or with the name of the object under mixed-list encoding conditions. After the free recall task, subjects had to make metamemory judgments about how many items of each format they had seen and recalled. The key result was that a superiority of bizarre pictures over common ones was found in all conditions although performance was better when the pictures were presented alone than with their corresponding label. Subsequent metamemory judgments, however, showed that subjects underestimated the number of bizarre items actually recalled.     

What has caused the Flynn effect? Secular increases in the Development Quotients of infants

Results of five studies show that during the second half of the twentieth century there were increases in the Development Quotients (DQs) of infants in the first two years of life. These gains were obtained for the Bayley Scales in the United States and Australia, and for the Griffiths Test in Britain. The average of 19 data points is a DQ gain of approximately 3.7 DQ points per decade. Similar gains of approximately 3.9 IQ points per decade have been present among preschool children aged 4–6 years. These gains are about the same as the IQ gains of school age students and adults on the Wechsler and Binet tests. This suggests that the same factor has been responsible for all these secular gains. This rules out improvements in education, greater test sophistication, etc. and most of the other factors that have been proposed to explain the Flynn effect. It is proposed that the most probable factor has been improvements in pre-natal and early post-natal nutrition.     

Is there an effect of handedness on the position of the egocentric reference?

Forty normal subjects (20 left-handed; 20 right-handed) were submitted to a proprioceptive straight ahead pointing task while blindfolded to study the effect of the hand used and of the hand preference on the estimation of the subjective sagittal middle. Results showed that left-handed and right-handed subjects both deviated to the left of the objective sagittal middle and presented an effect of the hand used and of the starting point affecting their straight ahead performance in a similar way. In all subjects whatever their manual preference, using the left hand and starting 30 degrees to left induced a tendency to deviate to the same side, whereas using the right hand and starting 30 degrees to right induced a tendency to place the subjective middle to the right of the objective middle. These results are interpreted with regard to the hypothesis of a cortical control of the position of the egocentric reference.     

Is banara really a word?

Bowers, Davis, and Hanley (Bowers, J. S., Davis, C. J., & Hanley, D. A. (2005). Interfering neighbours: The impact of novel word learning on the identification of visually similar words. Cognition, 97(3), B45-B54) reported that if participants were trained to type nonwords such as banara, subsequent semantic categorization responses to similar words such as banana were delayed. This was taken as direct experimental support for a process of lexical competition during word recognition. This interpretation assumes that banara has been lexicalized, which predicts that masked form priming for items such as banara-banana should be reduced or eliminated. An experiment is reported showing that the trained novel words produced the same amount of priming as untrained nonwords on both the first and the second day of training, suggesting that the interference observed by Bowers et al was not due to word-on-word competition.     

Is categorization performance really intact in amnesia? A meta-analysis

Most published studies of category learning in amnesia have reported intact categorization performance. These results have been used to challenge single-system accounts of categorization and recognition, in which a single representational system mediates performance in these two tasks. Many of the published studies, however, have shown a numerical advantage for controls over amnesics and often have had low statistical power. A meta-analysis was conducted to assess whether this numerical advantage is significant when the data are pooled across studies. This analysis indicates that amnesic subjects do, in fact, show deficits in categorization tasks, which is consistent with single-system exemplar model predictions.     

Is empathy associated with more prosocial behaviour? A meta-analysis

Empathy is an important prerequisite for prosocial behaviour (PB). However, different concepts and methodological tools have been used in research on the relationship between empathy and PB, leading to ambiguous results. This study used a meta-analysis to explore this relationship and to identify the moderating variables. After a literature search, 62 studies and 146 samples with 71,310 participants were included. Our random effects model revealed a positive correlation of PB with both cognitive empathy (r = .32) and affective empathy (r = .30). In addition, the relationship between empathy and PB is moderated by culture, publication type, education level, and empathy measures. Our conclusion is that there is a significant correlation between empathy and PB that is influenced by sample characteristics and methodological factors.     

Is implicit sequence learning impaired in schizophrenia? A meta-analysis

Cognition in schizophrenia seems to be characterized by impaired performance on most tests of explicit or declarative learning contrasting with relatively intact performance on most tests of implicit or procedural learning. At the same time there have been conflicting results for studies that have used the Serial Reaction Time (SRT) task to examine implicit learning in people with schizophrenia. In the present research, we used meta-analysis to clarify whether or not people with schizophrenia show impaired performance on the SRT task. A systematic review found nine studies published in peer review journals that had each compared the performance of a group of people with schizophrenia with healthy controls on the standard SRT task or a variant of it. The resulting meta-analysis represented the responses of 205 participants with schizophrenia and 159 healthy controls on the SRT task. The analysis found that participants with schizophrenia perform less well than controls reflected by a pooled effect size of 0.51. A secondary analysis of all nine studies found that they all reported a point estimate of the change in reaction time between sequence and random trials that was greater for the controls. We conclude that there is a moderate impairment in implicit sequence learning among people with schizophrenia and speculate on the implications of this for understanding this disorder. Suggestions for improving the methodological quality and statistical reporting of studies of this topic are made.     

Is caregiving hazardous to one's physical health? A meta-analysis

Caring for a family member with dementia is generally regarded as a chronically stressful process, with potentially negative physical health consequences. However, no quantitative analysis has been conducted on this literature. The authors combined the results of 23 studies to compare the physical health of caregivers with demographically similar noncaregivers. When examined across 11 health categories, caregivers exhibited a slightly greater risk for health problems than did noncaregivers. However, sex and the health category assessed moderated this relationship. Stronger relationships occurred with stress hormones, antibodies, and global reported health. The authors argue that a theoretical model is needed that relates caregiver stressors to illness and proffers moderating roles for vulnerabilities and resources and mediating roles for psychosocial distress and health behaviors.     

Is the inversion effect in rhesus monkeys face-specific?

This study investigated the face inversion effect in rhesus monkeys (Macaca mulatta). Face stimuli consisted of ten black-and-white examples of unfamiliar rhesus monkey faces, brown capuchin faces, and human faces. Two non-face categories included ten examples of automobiles and abstract shapes. All stimuli were presented in a sequential matching-to-sample format using an automated joystick-testing paradigm. Subjects performed significantly better on upright than on inverted presentations of automobiles, rhesus monkey and capuchin faces, but not human faces or abstract shapes. These results are inconsistent with data from humans and chimpanzees that show the inversion effect only for categories of stimuli for which subjects have developed expertise. The inversion effect in rhesus monkeys does not appear to be face-specific, and should therefore not be used as a marker of specialized face processing in this species. Received: 18 November 1998 / Accepted after revision: 9 May 1999