Overarching Intelligence Theory
Qi Li
The University of Georgia
There are many theories about the nature of intelligence. They are not incompatible with each other and each contributes to the study of intelligence from different perspective. Currently, there is no commonly-accepted definition of intelligence because scientists have not yet determined what factors affect intelligence. This article will not focus on the definition of intelligence but intends to present several commonalities that can be found in many current theories of intelligence.There are at least four common assumptions: (a) intelligence is a measurable concept; (b) intelligence is genetic related and (c) the development process of intelligence is dynamic and nonlinear. Each will be discussed more fully in the sections which follow.
Intelligence is a measurable concept
Virtually all theories assume that the factors that affect intelligence can be measured. This is one of the basic assumptions of the initial work on intelligence and remains true today. The earliest research on measuring human intelligence derived from Darwin’s (1859) statement that human intelligence could be understood through scientific investigation. In line with this, Galton proposed techniques for measuring human techniques through physical responses. From 1884 to 1890, he set up an anthropometric laboratory using psychophysical tests to measure visitors’ intelligence (Sternberg 1990) . Cattell, the successor of Galton, furthered the tradition. He believed that psychology could attain the certainty and exactness of the physical sciences only it rested on a foundation of experiment and measurement (Sternberg 1990) . As a step toward his statement, he proposed a series of 50 psychophysical tests in 1890.
Psychometrical theories of intelligence expand the broad of test items to more general cognitive abilities. In 1904, Binet and Simon shifted from pure scientific concerns to practical educational concerns to measure intelligence in order to decide that no child suspected of retardation should be placed in a special class for the retarded without first being given an examination. They went beyond the physical abilities and introduced many kinds of judgmental abilities in measuring intelligence. In addition, Binet’s test items considered the performance difference at different ages and levels.
As a continuum of this movement, many IQ tests were developed, such as: Stanford-Binet scale, Wechsler Adult Intelligence Scale, and Kaufman Assessment Battery for Children. Statistical analysis of the different tests reveals a general factor, or called “g”, which is defined as the largest common factor derived from IQ tests (Naglieri and Jenson 1987) . The core of psychometric measurement of intelligence is factor analysis, which is a multivariate technique for describing a set of measured variables in terms of a set of causal or underlying variables which are assumed to display human intelligence.
Many non-psychometric theories of intelligence also support this assumption. Two representatives of them are Sternberg’s triarchic theory and Gardner’s multiple intelligence theory. Sternberg’s triarchic theory claims that the understanding of intelligence can be reached by measurement through mental activity although his theory emphasizes the importance of context. Gardner claimed human beings have multiple intelligences, which is embodied by the corresponding abilities to solve problems, or to create products (Gardner 1983) . Intelligence can be understood by measuring these abilities in the corresponding domain. All these studies agree that the measurement of the factors which may influence the intelligence is the starting point to examine human intelligence.
Intelligence is a genetic related
Everyone was born with heritable traits from parents. These traits consist of the biological factors which influence the development of intelligence. Current studies show the genes contribute substantially to individual differences in intelligence although we still do not know the pathway by which genes produce their effects. Plomin’s (Plomin 1997) study found the genes account for 50% of the IQ variance.And the influence of genetic endowment on intelligence increases with age. The study of Swedish twins reared together and twins reared apart who were studies at the average age of 60 years showed heritability increases from about 40% in childhood to about 60% in early adulthood to about 80% in later life. About the influence of genetic difference on intelligence, Naglieri and Jenson (Naglieri and Jenson 1987) stated the average of IQ differences between Blacks and Whites might in part be the result of genetic differences or at least genetic related. Scarr and Mccartney also claimed the importance of genes. They (Scarr and McCartney 1983) stated that genes control the development of intelligence by influencing the selection of environment where the living experience happen. So I can not ignore the genetic influence since nobody can escape from the heritable genes from parents.
The development of Intelligence is a dynamic process
A number of intelligence theories assume that intelligence is in the process of development through life span. The process is dynamic and nonlinear. So the course of development is different for every individual. Current theories contribute to this assumption but they came to the point from different perspectives.
One perspective is that the development of intelligence is influenced by the society where the individual involved. Kornhaber, Krechevsky & Gardner (1990) claimed “intelligence is best conceived as the product of a dynamic process involving individual competences and the values and opportunities afforded by society” (p.177). They stated society foster individual development through the opportunities they provide, the institution the support and the value systems it promotes.
Another theory which supports this assumption is Vygotsky’s social-culture theory. Vygotsky stated that the development of intelligence depends on the continuous interaction with society. Vygotsky (1978) states:
"Every function in the child's cultural development appears twice: first, on the social level, and later, on the individual level; first, between people (interpsychological) and then inside the child (intrapsychological). This applies equally to voluntary attention, to logical memory, and to the formation of concepts. All the higher functions originate as actual relationships between individuals." (p57).
A second aspect of Vygotsky's theory is the idea that the potential for cognitive development depends upon the "zone of proximal development" (ZPD) which is the intellectual capacity of the individual when he or she is helped by others. It is a unique way of measuring intelligence in that it takes into consideration the capabilities of an individual within a social setting.
Vygotsky's theory was an attempt to explain the development of intelligence is the product of continuous social interaction. For example, in the learning of language, children’s first utterances with peers or adults are for the purpose of communication but once mastered they become internalized and allow "inner speech".
The second perspective is from the dynamic system theory. Lewis (2000) claimed that the dynamic system theory can provide a converging explanatory framework for the dynamic developmental process of intelligence. Traditional theoretical families each contributes to the study of development of intelligence from one perspective. They are incomplete or specialized. Based on review of the traditional theories, including mechanistic theories, organismic theories, contextualist approaches, learning theories, nativist theories and constructivist approaches, he claimed it is necessary to see the development change as indeterminate as well as principled, self-augmenting as well as unfolding, and creative as well as responsive. In other words, he used emergence instead of growth, learning or construction for characterizing the developmental change.
In conclusion, I see intelligence is a developmental and dynamic concept. Measurement of intelligence is best understood in a given context. The development of intelligence is influenced by myriad factors. Any research focusing on one single factor will not be complete but contribute to interpret the existence of influence. Further research on intelligence will focus on developmental, dynamic and process perspectives. New findings from the fields of genes, brain, psychology and cognition will continuously enrich the knowledge base about the theory of intelligence.
Reference:
Gardner, H. (1983). Frames of Mind. New York, Basic Books.
Kornhaber, M., M. Krechevsky, et al. (1990). Engaging Intelligence. Educational Psychologist, 25, 177-199.
Lewis, M. D. (2000). The promise of dynamic systems approaches for an integrated account of human learning. Child Development, (71), 36-43.
Naglieri, J. A. & Jenson, A. R. (1987). Comparison of black-white differences on the WISC-R and the K-ABC: Spearman's Hypothesis. Intelligence, 11, 21-43.
Plomin, R. (1997).Genetics and Intelligence: What's New? Intelligence, (24), 53-77.
Scarr, S. & McCartney, K. (1983). How people make their environments: A theory of genotype environmental effects. Child Development, (54), 424-435.
Sternberg, R. J. (1990). Metaphors of Mind: Conception of the Nature of Intelligence. Cambridge University Press.
Vygotsky, L. S. (1978). Mind in Society: the development of higher psychological processes. Cambridge, MA, Harvard University Press.