ABSTRACT
By the end of the 1970s most developmental psychologists were acknowledging a new body of descriptive and experimental evidence which indicated that cognitive (i.e. thinking) decline was not a necessary consequence of ageing. This evidence and the research methodology which produced it constituted an effective challenge to a much larger body of psychological evidence which had supported the socially persistent stereotype of inevitable and irreversible decline with advancing age. In the 1960s psychologists had formulated more complex and sophisticated research designs, in order to correct recognised biases in the designs which were normally used to produce descriptive evidence on development. What they found was that whether or not individuals’ cognitive or thinking abilities decline, remain stable or continue to develop over the years of adulthood ‘depends’ on the interplay of many factors. Psychologists began to recognise that development, or the lack of it, during adulthood was inextricably linked to the degree and quality of individuals’ interactions with their social and historical contexts. Since such interactions could fluctuate the pattern of development could as well. This model of development has been called the ‘plasticity’ model.
