A wealth of perceptual load theory research has suggested that different types of attentional demand can have opposite effects on perceptual processing: high perceptual demand reduces such processing whereas high cognitive demand increases it. However, this distinction has not been made within the eating behaviour literature. This thesis applied perceptual load theory to multiple aspects of eating behaviour. A series of behavioural studies tested whether processing of food-related cues and information related to consumption would also be reduced by manipulating the perceptual demand in a central task.
Papers one and two used established perceptual load paradigms to investigate external and internal processing of food-related cues. Paper one established that both attentional processing and recognition accuracy of external food stimuli were reduced by high perceptual load. There was tentative evidence that some individual differences (uncontrolled eating, hunger and body mass index) in the recognition accuracy of food stimuli persisted even under high perceptual load. Paper two found that high perceptual load also reduced appetitive-related thoughts. This effect was found across individuals, regardless of the number of appetitive-related thoughts reported under low perceptual load.
Papers three and four adapted the perceptual load task to allow simultaneous food consumption. Paper three found no evidence that high perceptual load reduced flavour awareness or influenced intake. Paper four found that participants were unable to respond to internal satiety signals when engaged in the high perceptual load task. This was reflected by failure to reduce intake and experienced satiety in response to consuming a high energy preload.
Overall, these studies have suggested that perceptual load theory is a valid framework for understanding eating behaviour. This has implications for both the eating behaviour and attention literatures. Most importantly, perceptual load theory could be used to predict the situations in which attention can be a help or a hindrance to appetite control
