One of the greatest paradoxes of our time is that people are getting heavier, even though everyone seems to be dieting to lose weight. Research has shown that dieters experience a preoccupation with food and overeating behaviour; however, little is known about what factors underpin the preoccupation with food and overeating behaviour so commonly reported in dietary restraint. The aim of this thesis is to understand why dieting produces cognitive and behavioural effects which are precisely the opposite of what one intended when they engaged in dietary restraint. Ironic Processes Theory (IPT; Wegner, 1994) was originally developed to explain why people who are instructed to suppress thoughts about a white bear reported an increase in white bear thoughts during suppression and a rebound of white bears thoughts when then the instruction to suppress was terminated. The mechanism proposed by Wegner (1994) to explain why people struggle with thought suppression can also be applied to understand why dieters struggle to control their food intake. The attempt to avoid food, both cognitively and behaviourally, initiates a monitoring process which is tuned to search for food and sends a signal to the operating process to direct attention away from food. Dieters are able to avoid food as long as they have sufficient cognitive resources. However, any threat to these resources through additional physical (time constraints) or psychological demands (stress) will disable the operating process and the dieter will find food difficult to avoid. According to IPT, avoiding food is the key factor which underpins a preoccupation with food and overeating behaviour. The relevance of IPT in dietary restraint was investigated through a series of dot probe and recognition experiments, which measure an attentional and memory bias for food. An attentional bias which directs attention away from forbidden foods and towards non-forbidden foods would support the operating and monitoring processes in dietary restraint. However, a memory bias which is more accurate for forbidden foods would support the hypothesis that avoiding food underpins a preoccupation with food. It was also decided toinvestigate whether the operating and monitoring processes could be dissociated with a threat to cognitive resources. This was achieved by measuring an attentional and memory bias for food following a violation to dietary restraint. Finally, a qualitative analysis of avoiding food, preoccupations with food and overeating behaviour was conducted to investigate the ecological relevance of these phenomena in the dieter’s natural environment. The results obtained in this thesis offered some support for the hypothesis that avoiding food underpins a preoccupation with food and overeating behaviour; however, the support available for IPT was confined to the collection of qualitative data. All participants, irrespective of level of dietary restraint, preload condition, and gender status, consistently displayed an attentional and memory bias which drew their attention towards forbidden foods and away from non-forbidden foods. This effect was observed when both pictorial and linguistic stimuli were used in the dot probe task and suggests that an attentional bias for food is not confined to restrained eaters. The non-significant effect of dietary restraint in the experimental chapters prompted an investigation of the reliability of the dot probe task. The item analysis found that participants failed to respond to food stimuli in a predictable and reliable fashion, which was required to support the division of foods into forbidden and non-forbidden categories. The results obtained in the qualitative investigation offered some support for IPT in that dieters were found to avoid food, experience a preoccupation with food and overeating behaviour. There was also considerable evidence to suggest that avoiding food underpins a preoccupation with food and overeating behaviour. However, the results revealed that avoiding food is not the only factor which underpins the negative cognitive and behavioural effects associated with dietary restraint. Dieters described a range of cognitive and behavioural phenomenon which could not be adequately explained by IPT (e.g. food addiction, compensatory behaviours and time effects). It was concluded that there is some support for IPT in dietary restraint, however the experience of dietary restraint was far more complex than IPT predicts. The results obtained in this thesis were examinedinvestigate whether the operating and monitoring processes could be dissociated with a threat to cognitive resources. This was achieved by measuring an attentional and memory bias for food following a violation to dietary restraint. Finally, a qualitative analysis of avoiding food, preoccupations with food and overeating behaviour was conducted to investigate the ecological relevance of these phenomena in the dieter’s natural environment. The results obtained in this thesis offered some support for the hypothesis that avoiding food underpins a preoccupation with food and overeating behaviour; however, the support available for IPT was confined to the collection of qualitative data. All participants, irrespective of level of dietary restraint, preload condition, and gender status, consistently displayed an attentional and memory bias which drew their attention towards forbidden foods and away from non-forbidden foods. This effect was observed when both pictorial and linguistic stimuli were used in the dot probe task and suggests that an attentional bias for food is not confined to restrained eaters. The non-significant effect of dietary restraint in the experimental chapters prompted an investigation of the reliability of the dot probe task. The item analysis found that participants failed to respond to food stimuli in a predictable and reliable fashion, which was required to support the division of foods into forbidden and non-forbidden categories. The results obtained in the qualitative investigation offered some support for IPT in that dieters were found to avoid food, experience a preoccupation with food and overeating behaviour. There was also considerable evidence to suggest that avoiding food underpins a preoccupation with food and overeating behaviour. However, the results revealed that avoiding food is not the only factor which underpins the negative cognitive and behavioural effects associated with dietary restraint. Dieters described a range of cognitive and behavioural phenomenon which could not be adequately explained by IPT (e.g. food addiction, compensatory behaviours and time effects). It was concluded that there is some support for IPT in dietary restraint, however the experience of dietary restraint was far more complex than IPT predicts. The results obtained in this thesis were examinedinvestigate whether the operating and monitoring processes could be dissociated with a threat to cognitive resources. This was achieved by measuring an attentional and memory bias for food following a violation to dietary restraint. Finally, a qualitative analysis of avoiding food, preoccupations with food and overeating behaviour was conducted to investigate the ecological relevance of these phenomena in the dieter’s natural environment. The results obtained in this thesis offered some support for the hypothesis that avoiding food underpins a preoccupation with food and overeating behaviour; however, the support available for IPT was confined to the collection of qualitative data. All participants, irrespective of level of dietary restraint, preload condition, and gender status, consistently displayed an attentional and memory bias which drew their attention towards forbidden foods and away from non-forbidden foods. This effect was observed when both pictorial and linguistic stimuli were used in the dot probe task and suggests that an attentional bias for food is not confined to restrained eaters. The non-significant effect of dietary restraint in the experimental chapters prompted an investigation of the reliability of the dot probe task. The item analysis found that participants failed to respond to food stimuli in a predictable and reliable fashion, which was required to support the division of foods into forbidden and non-forbidden categories. The results obtained in the qualitative investigation offered some support for IPT in that dieters were found to avoid food, experience a preoccupation with food and overeating behaviour. There was also considerable evidence to suggest that avoiding food underpins a preoccupation with food and overeating behaviour. However, the results revealed that avoiding food is not the only factor which underpins the negative cognitive and behavioural effects associated with dietary restraint. Dieters described a range of cognitive and behavioural phenomenon which could not be adequately explained by IPT (e.g. food addiction, compensatory behaviours and time effects). It was concluded that there is some support for IPT in dietary restraint, however the experience of dietary restraint was far more complex than IPT predicts. The results obtained in this thesis were examined
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:544495 |
| Date | January 2010 |
| Creators | Gilchrist, Leanne |
| Publisher | University of the West of Scotland |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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