Inteliigence

Intelligence is a controversial area in psychology and defining intelligence is problematic. The main theoretical approaches are the differential approach: which devises psychometric tests to measure the differences in individual's abilities to solve problems. The developmental approach concerned with perception, manipulation and reasoning in the developing infant and the information processing approach that investigates the skills used in reasoning and problem solving (see Carlson and Buskist 1997). Cognitive psychologists agree that intelligence involves the capacity to acquire and remember information, recognise and relate concepts and to adapt individual behaviour in line with information (Neisser, Boodoo, Bouchard, Boykin, Brody, Ceci, Halpern, Loehlin, Perloff, Sternberg and Urbina (1996a, in Carlson, Martin and Buskist 1997). However, opinions vary as to the nature, mechanisms and even relevance of intelligence; whether intelligence is unitary or multiple factored is a topic of debate. Thus, this essay will begin with an outline of the statistical definition of intelligence with reference to factor analysis and the formation of a hierarchical structure of intelligence. The essay moves on to consider alternative theories of intelligence and then evaluates the pros and cons for each theory. The essay concludes by considering the usefulness of intelligence testing in general.

Factor analytic theories of intelligence, measure the performance scores obtained from a psychometric test e.g. the Wechsler adult intelligent scale (Weschler, 1939 in Carlson et al., 1997). Large samples scores are generally obtained and are analysed using a statistical technique called factor analysis (Carlson et al. 1987).This procedure identifies inter-correlations between tests items. The basic assumption is that comparable test scores suggest that similar factors are being measured and thus by a means of data reduction only key factors should emerge. According to Spearman (1904, in Hayes 2000) scores obtained in numerous small tests can provide evidence for a general factor. His two-factor theory suggests that performance on a test is determined by two factors: the G factor, a form of general intelligence common in all intellectual tasks (Carlson and Buskist 1997) and considered to be innate (Hayes 2000) and the S Factor, a factor of intelligence that is specific to a particular task, (Carlson and Buskist 1997). Studies that have used factor analysis include Spearman (1927 in Carlson et.al) who found correlations in children's abilities and resulted in the formation of the aforementioned theory. Birren and Morrison (1961, in Carlson and Buskist 1997) administered the WAIS and identified three factors; Horn and Cattell (1966, in Carlson and Buskist 1997) found only two: fluid intelligence (speed and accuracy of abstract reasoning) and crystallised intelligence (accumulated knowledge and vocabulary). However, Thurstone (1938, in Gross 1996) research of adolescents and college students found that not all mental tests correlate equally and as a result proposed seven distinct primary mental abilities which constitute intelligence. Carroll (1993, in Sternberg 2003) proposed a hierarchical model derived from more than 460 data sets obtained between 1927 and 1987 comprises of three levels: the first layer includes basic abilities e.g. spelling ability. The second includes broad abilities e.g. fluid and crystallised intelligence and the level three, a single general intelligence.

Criticisms of the use of factor analysis in defining intelligence merely explains occurrences between different types of data and thus the results are dependent

upon the factor items and the arbitrary and subjective decisions of the researcher (see Eysenck p750 2000).Thus factor analysis may provide clues about the nature of intelligence, statistics cannot define intelligence. This inability to define is demonstrated by the variance in results obtained from the various studies, agreements differ as to whether intelligence depends upon one factor or a multiple of factors.

Alternative theoretical approaches seek to understand intelligence. Sternberg's triarchic theory of intelligence (1985 in Hayes 2000) adopts an information- processing approach to intelligence which suggests three distinct aspects to intelligence which work together to produce intelligent behaviour:

Componential intelligence involves the mental mechanisms used in intelligent functioning e.g. verbal ability and deductive reasoning (Carlson et.al., 1987). Experimental intelligence is about the ability to apply past experience to novel situations such as problem solving, and the efficiency in which tasks become automated e.g. reading. Contextual intelligence refers to the ability to apply mental mechanisms to the external environment through processes of adaptation, selection and shaping. The model with its various sub-sets provides a more comprehensive account of intelligence with its' recognition of context and experimental aspects of intelligence and the possibility that there are universals in intelligence which can be assessed cross culturally (see Hayes 2000). However, evidence suggests that several areas of the brain may be involved in the performance of even the simplest of tasks and therefore, continued research in this area is desirable.

An alternative model is Gardner's theory of multiple intelligences (1985, in Carlson et.al., 1987) and derives from neuropsychological analysis of human abilities. It suggests that there are seven independent abilities: linguistic; musical; mathematical; spatial; bodily/kinetic; intrapersonal and interpersonal. Gardner provides evidence drawn from various sources: developmental; brain damage; extreme cases and evolutionary evidence (see Hayes 2000).Each ability can be located within the brain e.g. damage to the left parietal lobe can result in axpraxia, which affects the ability to perform voluntary movements; or damage to the right hemisphere can impair social skills (Carlson and Buskist, 1997). This model widens the scope of intelligence by the inclusion of musical ability and intrapersonal intelligence. However, criticisms suggest that much of Gardner's evidence is anecdotal in terms of the fact that he regards calculation; mathematics and hypothesising as equal (see Hayes 2000). Although this model accepts the social aspects of intelligence but does not relate this skill to the other areas identified as abilities