غذای کمتر برای فکر. اثرات دستورالعمل توجه در مورد افکار مزاحم در مورد غذاهای سرپایی

Intrusive thoughts about food have an important role in maintaining dysfunctional eating behaviours, primarily by triggering craving (McManus & Waller, 1995), and act as a proximal trigger for lapses when people are trying to restrict intake (Loewenstein, 1996). Food cravings have been shown to lead to episodes of binge-eating (Gendall, Joyce, Sullivan, & Bulik, 1998), to predict dropout from weight-loss programs (Sitton, 1991), and have been linked to obesity (Schlundt, Virts, Sbrocco, & Pope-Cordle, 1993). Even if intense desires to eat are resisted, they induce discomfort and distress, and divert attention from other cognitive tasks (Green, Rogers, & Elliman, 2000). Self-report data suggest that the phenomenology of craving for food is similar to craving for addictive drugs; craving across a range of addictive and everyday substances involves intrusive thoughts and mental images of consumption (Kavanagh et al., 2009, May et al., 2008 and May et al., 2004). Understanding the cognitive and emotional processes that generate these craving thoughts and images should allow more effective techniques to be developed to attenuate cravings, helping people to refrain from consuming substances they are trying to avoid. The Elaborated Intrusion theory of desire (EI theory; Kavanagh, Andrade, & May, 2005) describes craving as an episode of imagery-based cognitive elaboration that follows an intrusive thought about a target. Physiological deficit, negative affect, external cues, other cognitive activity, and anticipatory responses to the target can all trigger associative processes that occur beneath awareness and that result in an apparently spontaneous target-related thought, where the ‘target’ is the desired substance or activity. This intrusive thought marks the beginning of the craving episode for the individual, since it is the first thought that they are aware of. In EI theory, intrusions can prompt elaboration: conscious, controlled processing that involves the internal and external search for target-related information, and the retention and elaboration of this information in working memory, which serves to further maintain the craving episode. Self-report data from questionnaire studies support the idea that sudden, intrusive thoughts and vivid sensory images are important features of craving (Kavanagh et al., 2009, May et al., 2004 and May et al., 2008). Recent research suggests that disrupting craving imagery, with competing neutral imagery tasks, reduces subjective craving levels in abstaining smokers (Pannabokke, 2004 and Versland and Rosenberg, 2007), dieters (Kemps, Tiggemann, Woods, & Soekov, 2004) and undergraduates induced to crave food or chocolate (Kemps & Tiggemann, 2007). However, little research has specifically focused on intrusive thoughts in craving. According to EI theory, intrusive thoughts do not automatically trigger elaborative craving. Rather, the subsequent elaboration depends upon the salience of the intrusion relative to competing task demands and goals. Even in a sample of people seeking treatment for alcohol dependency, 87% of respondents sometimes experienced momentary intrusive thoughts about alcohol that vanished spontaneously without elaboration (Kavanagh et al., 2009). Interventions that focus on preventing an elaborative response to the initial target-related intrusion, therefore, offer the potential to prevent full-blown craving episodes developing. The present study explores such interventions, some based upon mindfulness, or acceptance-based, approaches. Mindfulness-based therapies, which incorporate thought control techniques such as Breath Focus and Body Scanning, teach individuals to notice and accept unwanted thoughts as just thoughts, without entering into cycles of negative appraisal or rumination (Kabat-Zinn, 2003). Mindfulness to the person's continually changing sensory experience is also likely to increase the salience of other thoughts which may compete with the negative thoughts (e.g., cognitive associations or sensory awareness of other events or internal states). Beneficial effects have been claimed for mindfulness-based therapies in a wide range of conditions in which intrusive thoughts are typical, including depression, generalized anxiety disorder, psychosis, and grieving (Teasdale et al., 2000, Orsillo et al., 2003, Sagula and Rice, 2004 and Watkins and Teasdale, 2004). In substance misuse, mindfulness-based interventions have been shown to reduce relapse, possibly by allowing people to alter the relationship that they have with the difficult cognitions that act as triggers to their cravings, and by enabling people to recognize and monitor cravings as they occur (Breslin et al., 2002 and Marlatt, 2002). Recently, Ussher, Cropley, Playle, Mohidin, and West (2009) found that listening to a Body Scanning or an isometric exercise instruction tape reduced desire to smoke, compared to a control group who had listened to a reading about natural history. In contrast to mindful acceptance, a common alternative way to deal with unwanted intrusive thoughts is to try to suppress them: the intent of Thought Suppression is to prevent unwanted thoughts from occurring at all rather than on one's response to them. Evidence is mixed on whether this exacerbates the problem or is an effective strategy. Some studies suggest that suppression has the ironic effect of increasing intrusive thoughts, either when undertaking the suppression (Lavy & van den Hout, 1990) or afterwards (Wegner, Schneider, Carter, & White, 1987), because in order to check that one is not thinking of something, one has to think about it—this has been called the ‘ironic effect’ of Thought Suppression (Wegner, Erber, & Zanakos, 1993). Indeed, it has been argued that repeated suppression of unwanted thoughts can have such a negative effect as to be a causal and maintenance factor in much mental illness (Hayes, Wilson, Gifford, Follette, & Strosahl, 1996): for example, promoting depressive rumination (Wenzlaff & Luxton, 2003) and exacerbating symptoms in anxiety and obsessive-compulsive disorder (Becker et al., 1998 and Purdon, 2004). Negative effects of suppression can also be seen in some studies on craving. In Kavanagh et al. (2009), the more frequently participants had tried to suppress alcohol-related thoughts, the more alcohol thoughts they had. Greater attempts to suppress alcohol-related thoughts were associated with stronger craving and a more extended craving episode. In Salkovskis and Reynolds (1994), participants who were in a Thought Suppression condition had more intrusive thoughts during and after the task, than did those in a thought-monitoring condition. However, suppression of thoughts is not always counter-productive. Suppression often has no effect on personally relevant or emotional thoughts (Kelly and Kahn, 1994, Muris et al., 1992 and Wegner and Gold, 1995) and can result in short-term reductions in thoughts, provided there is no concurrent task to capture attentional resources (Wegner, 1989). Nosen and Woody (2009) found that a tendency to suppress unwanted thoughts was not a factor in predicting the success of quit smoking attempts. Furthermore, if the person responds to suppression instructions by ignoring the thought and thinking about other things, or relinquishes efforts to monitor the occurrence of the target thought, there is no theoretical reason why suppression should not work. Using a specific, unrelated thought for distraction reduces the rebound effect (Wegner et al., 1987) and instructing people to ignore, rather than suppress, thoughts about snack foods reduces consumption (Achtziger, Peter, Gollwitzer, & Sheeran, 2008). We therefore included a Thought Suppression condition in which participants were asked to divert their thoughts to imagery of a particular self-relevant activity. We focused on the use of imagery, since as already noted, competing imagery reduces craving for a range of appetitive targets (Kemps and Tiggemann, 2007, Kemps et al., 2004, Pannabokke, 2004 and Versland and Rosenberg, 2007). Interfering with food imagery through competing imagery tasks should break the cycle of cognitive elaboration of the desire, which otherwise leads to further thoughts about the appetitive target.