Effects of cognitive distraction on the regulation of human eating behaviour
In humans, what, when, and how much is eaten is the result of a complex interplay between physiological and psychological dietary controls. The need to identify how these different influences interact is integral to understanding how eating behaviour is regulated in a range of different contexts. In particular, one phenomenon that remains poorly understood is why eating while distracted is associated with increased food intake. The aim of this thesis is to attempt to identify the nature of the potential process that underlies this phenomenon. In Part I, the relationship between dietary strategy, allocation of attention, and amount eaten is explored in three experiments. The results confirm that intake can be predicted by how attention is directed during a meal. Furthermore, contrary to previous accounts that view overeating as a passive behaviour, this research suggests that individuals may choose to direct their attention strategically in order to control their intake. In Part II, four experiments investigate the possibility that the mechanism underlying the relationship between attention and intake is related to a process akin to ‘sensory-specific satiety'. This term describes the hedonic shift in the sensory properties of a food that occur as it is eaten and which is believed to be important in meal termination. The results suggest that distraction is associated with an attenuation of the rate at which ‘desire to eat' (both generally and specifically for the food being eaten) declines. Furthermore, although declining pleasantness is reported to remain influential in determining eating cessation when distracted, this response is somewhat inhibited, occurring after a greater amount of food has been consumed. Based on this, the conclusion drawn is that the deficit underlying overeating is one of attention, and that this may lead to overeating by undermining the rate at which satiety develops.