A multidisciplinary investigation into socioeconomic variation in behaviour

Abstract

Socioeconomic differences in behaviour are widely documented, but are not yet well understood. I propose that they can be better understood by using concepts from evolutionary theory. Evolutionary theory predicts that mortality risk should be important in determining life history traits such as the scheduling of growth and reproduction. An extension of this concept is that mortality risk should influence the degree to which people value benefits and costs in the present versus those in the future. Thus, many socioeconomic differences in behaviour may represent differences in time perspective, generated by inequalities in mortality risk. This raises the question of what cues evolved psychological mechanisms rely on when forming their estimates of personal mortality risk. I first report a test of the hypothesis that the deaths of others are used as a cue to mortality risk. The results showed that experiences of close bereavement are associated with steeper future discounting and earlier ideal, and actual, reproductive timing (Chapter 2). I then report the results of two experimental tests of whether the ages of others might be used as an indicator of local mortality rates. Manipulating the age profiles of sets of faces viewed in laboratory experiments did not have a clear effect on future discounting or reported ideal reproductive timing (Chapter 3). I move on to testing the hypothesis that the controllability of mortality risks should be most important for behaviour. The results of a correlational study showed that perceived extrinsic mortality risk mediated the association between socioeconomic status and effort spent looking after health (Chapter 4). I then report three experiments that demonstrate that priming participants to feel that prevailing sources of mortality risk are, or are not, controllable alters a simple health behaviour – the choice of a healthy food reward (Chapter 5). Finally, I review the bigger picture of socioeconomic differences in behaviour. I explain how the lack of control associated with lower socioeconomic status may lead to present-oriented behaviour in a range of domains – a phenomenon that I have called the Behavioural Constellation of Deprivation. I highlight some principles from evolutionary theoretical models that can deepen our understanding of how socioeconomic inequalities can become amplified and embedded. I discuss mechanisms by which extrinsic mortality risk may influence behaviour. I then review the evidence in support of my position, highlighting the fact that many researchers working from different perspectives have converged on control and time perspective as explanations for socioeconomic differences in behaviour. I finish by discussing the wider implications of my thesis and some of the related questions which could be answered in future research (Chapter 6 & 7).