Conceptions of Intelligence

global property of the human central nervous system (CNS) which determines the efficiency with which any cognitive task can be performed; that, consequently, the 'biological basis of intelligence' must be discussed in terms of factors that determine the maximum rate at which neural networks can transmit information, and that, if defined in this way, 'intelligence' must inevitably decline as the brain ages and becomes less efficient (Salthouse 1982, 1985, iggi). Most people and psychologists define ' intelligence' pragmatically as the ability to solve the problems encountered in everyday life. Zoologists tend towards similar definitions and have difficulty comparing the 'intelligence' of species of different animals with equally successful, albeit intensely specialised, adaptations to diverse ecological niches. In this conceptual framework, intelligence is 'what works best' for an animal or a person. The specialised survival adaptations of academics, aborigines and artists can be regarded as equally valid manifestations of'intelligence', in the sense that they can all be successful ways of coping with different, complex life demands. In terms of this contextual model of intellectual development, intelligence is defined as ' the mental ability involved in successfully adapting to one's environment'. In the sense that as people age they must adapt to radically altered environments, problems and life-roles, it may be more appropriate to say that their intelligence must certainly qualitatively alter as they grow old but does not necessarily decline. Conceptions of Intelligence 271 This makes Robert Sternberg's latest investigations of the public definitions of intelligence of particular interest to readers of Ageing and Society. Berg and Sternberg ask whether the quality that we define as intelligence, or the general definitions of intelligence on which most are prepared to agree, differ with the ages of the people we take as exemplars. They argue that an exploration of common usage is not trivial because: 'Lay adults' assessments (of intelligence) are important because they serve as the basis for informal assessments of the intelligence of others and self and may impact and be predictive of current and future intellectual performance'. Perhaps they mean that people's views of intelligence may affect the way in which they regard themselves and others, and so may alter their behaviour. Berg and Sternberg argue that 'intelligence as a concept exists only as a resemblance to the prototype of an intelligent person. That is, degree of intelligence is estimated by the degree to which the individual corresponds to his or her culture's prototype of an exceptionally intelligent person'. It is worth noting that acceptance of this definition lures us well beyond moderate statements by other, equally distinguished, psychometricians who leave some place for the idea that intelligence is at least partly determined by a 'general ability', which is plausibly determined by neurobiology, and so by genetic inheritance, and which may set limits to the efficiency with which new life demands can be met and new roles learned (Spearman, 1904; 1927). An instance is Paul Balthes' balanced remark that, 'with aging. domains of psychological functioning other than performance on intelligence tests gain in relative significance'. If intelligence is to be defined in terms of socially observed exemplars or prototypes it is important to ask what these may be. Berg and Sternberg asked 152 individuals aged from 17 to 83 years to list behaviours that they regarded as being intelligent. These volunteers produced a list of 214 behaviours, which was edited to remove redundancy. A further 140 individuals from the same age range rated each behaviour in this reduced list on a nine point scale for applicability to young (30 years), middle-aged (50 years), and elderly (70 years) people. As Berg and Sternberg expected, there was a marked discrepancy in terms of the attributions of these behaviours to the three different age groups. 'Intelligent behaviours' seen to be characteristic of 30 year old people correlated with those for 50 year olds at r = 0.80, but with those for 70 year olds at only r = 0.16. Ratings for hypothetical 50 and 70 year old's correlated at r = 0.59. This seems to reflect a marked change in the perceived quality of intelligence between 50 and 70 years. An elaborate multivariate analysis allowed Berg and Sternberg to suggest that the listed behaviours could be classified into: