Studying intelligence the hard way

An Overview of Research into the Cognitive Basis of Intelligence

Abstract. This paper provides an overview of the research into the cognitive basis of intelligence. This research explains cognitive abilities in terms of cognitive units or properties of such units. Furthermore, this research is characterized by the application of so-called elementary cognitive tasks. The various approaches of this research originate from the concepts of cognitive psychology: Mental (and perceptual) speed, attention, working memory, memory access, and learning. All the approaches led to measures which correlate with measures of intelligence. The enormous importance of the cognitive basis is highlighted by the observation that predictors taken from the various approaches explain approximately 50% of the variance of intelligence. At the latent level the rate of explanation seems to surmount the 70% barrier. Furthermore, the problems and perspectives of the approaches are addressed.

The Raven's progressive matrices: change and stability over culture and time

Data relating to the stability and variation in the norms for the Raven's Progressive Matrices Test (a well-validated measure of basic cognitive functioning) for different cultural, ethnic, and socioeconomic groups on a worldwide and within-country basis are first summarized. Subsequent sections deal with variation over time. A possible explanation for the variation in norms over time and between ethnic groups within countries is offered.