Helen Davis

The best test of any relationship’s significance in a person’s life is. Perhaps, what happens when it comes to an end. Although losing a pet has been likened to losing a valued possession or occupation (e.g., Parkes, 1971), current evidence suggests that an owner’s response to pet death usually has more in common with bereavement following the death of a beloved human than with the loss of a possession (Archer & Winchester, 1994). Grief is a normal response to the death of a beloved other and has been characterised as progressing through a series of stages or phases from initial shock, numbness, and denial, occurring even when the death is expected, to a range of intense emotional reactions that may include anger and guilt, to depression and helplessness, where a person may become withdrawn, to a stage of dialogue and bargaining, where the bereaved person may begin to reach out to others, want to tell their story, and struggle to find meaning in what happened. The final stage involves acceptance of the loss and moving on (Kühler-Ross, 1969). The nature of response to pet death seems to follow this pattern, though being on average less extremely distressing and less prolonged (Archer & Winchester, 1994; Gerwolls & Lahott, 1994). People vary considerably in how they manifest their grief. Nevertheless, some bereaved persons may find their response severely debilitating and protracted and may even become suicidal (Archer & Winchester, 1994). This is termed complicated or pathological grief (Williams & Mills, 2000).

It has sometimes been uncritically assumed that involution mirrors development, so that individuals regress through developmental stages in a sort of inverse ‘decalagc’, A useful antidote is to remember that the intellectual and methodological problems of describing growing up and aging are very different. Understanding how children manage to acquire cognitive skills and modes of representation of the world that they could not previously attempt requires a quite different intellectual approach from understanding how older people cease to be capable of skills and modes of representation at which they once were superbly competent. However recent, reductionist general models for cognitive changes throughout the lifespan, while ignoring questions of changes in representational structure and skill acquisition and loss, propose that at any stage in the lifespan attainable levels of competence at all cognitive skills is limited by the current level of a single global factor which increases with developmental age, maintains a long plateau at maturity, and ebbs in senescence. Simplistic versions of this idea have directly equated this resource with a single, measurable performance index: the maximum speed with which individuals can make correct decisions in easy laboratory experiments. An attraction of this approach has been that it seems to provide a way of linking empirically measurable behavioural competence to potentially measurable functional property of the cognitive system and even to neurophysiological efficiency, providing, as one author his put it. a biological basis for intelligence’ (Eysenck, 1986). This chapter considers the historical evolution and current plausibility of this general model in three separate fields of research: individual differences in general intelligence, cognitive ageing and developmental psychology.

In this chapter, the authors examine the question of whether within-age and between-age differences in intellectual ability are really just two manifestations of the same phenomenon, corresponding to a single theoretical dimension, or whether there is reason to distinguish between the two kinds of variation and consider them as two theoretical dimensions. The authors then demonstrate how the fields of individual differences and development took divergent paths. The authors explore some current theories of within and between-age differences and attempt to draw together evidence to answer the question. The authors conclude with suggestions for directions in future research.