Memory Bias Towards Food-related Cues In Restrained Eater

Under the influence of social culture and environment,there is a general trend of dissatisfaction about weight and body type in women,who seek for different ways of losing weight.Reducing energy intake is an important strategy for obesity people,also acting as a common method of losing weight.However, inappropriate use of this strategy could easily lead to restrained eating. Restricted eating resembles the pathologies of anorexia nervosa in many ways, both behaviorally and cognitively. Restrained eaters are at high risk of eating disorder patients,and they are also a key stage in the transformation from unhealthy psychological to unhealthy behavior. Rather than direct biological mechanism-like signals of starvation or satiation from the body-restrained eating is controlled by cognition processing. Compared with unrestrained eaters, once restrained eaters were in exposure to food cues, whether they smelt the smell of delicious food or just saw them, their strong desire of food intake would be aroused. Therefore, food cues would arouse restrained eaters’strong desire of eating in compare with unrestrained eaters, thus affecting the execution of weigh-control goal of restrained eaters and leading to binge eating behavior. Coming along with restrained eating is repeating dieting and binge eating, as a consequence, restrained eaters suffered from emotional disorders, self-abasement, anxiety and depression,in some extreme cases they even had suicidal tendency, which had harmful influence on individual health. For those reason, research and study on restrained eating could not only enrich the theory of restrained eating, but also providing guidance to clinical treatment of eating disorders. In the recent years, plenty of studies focused on restrained eating’s influence on cognitive processing(for example, executive function), as well as the cognitive character of restrained eaters, in the hope that those studies could provide theoretic explanation and regulation to their eating behavior management, and those result could be applied to the clinical intervention and treatment.Previous researchers investigated the character of primary stage of information stage among in restrained eaters by using attention paradigm. Researches about restrained eaters’memory character focused mostly on long-term memory, rarely paying attention to working memory performance of restrained eaters. Working memory (WM) can be regarded as the fundamental cognitive processing system, which serves to remember the moment-to-moment rules of action and allocate processing capacity to other, ongoing cognitive activities. The updating component of working memory also has close relationship with complex executive function, such as goal achievement, planning, and adjustment to changes in environment. To achieve weight-control goal, restrained eaters must monitoring their eating behavior every now and then, and stick to their dieting plan at the same time. This suggests that working memory may play an important role in weight maintaining. Are there any working memory biases to food related cues in restrained eaters? If those biases do exist, do they still have influences on long-term memory performance? Restrained eaters can be divided into two sub-groups, that is successful restrained eaters and unsuccessful restrained eaters. Is there any difference in working memory processing character between two sub-groups of restrained eaters? If so, dose this difference the key to successful restrained eating? Present study would focus on the questions mentioned above and try to give explanations. In the present study, we adopt an n-back task involving food pictures as targets and distractors to explore working memory performance and a classic recognition task to investigate long-term memory, including two researched in total.Study 1 investigate the working memory performance of restrained eaters and unrestrained eaters under a normal state. High-calorie food picture, low-calorie food picture, and neural object pictures were used as stimuli. And after the working memory task, a recognition task was introduced to explore the long-term memory performance. We found that restrained eaters showed prolonged reaction time than unrestrained eaters in response to neutral object, and in the recognition task, restrained eaters recalled more high-calorie food picture than unrestrained eaters.In study 2, we further distinguish two sub-groups of restrained eaters,successful restrained eaters and unrestrained eaters and we used food pictures as stimuli. An fMRI was introduced to investigate working memory bias and the neural mechanism behind it under a fasting state. We found that when the stimuli was high-calorie food picture, successful restrained eaters got a significant lower accuracy than unrestrained eaters and unsuccessful eaters. Our fMRI result showed that, compared with unrestrained eaters,successful restrained eaters exhibited lower activation in right middle occipital gyrus when performing working memory task while unsuccessful restrained eaters exhibited lower activation in right superior parietal lobule(SPL). Successful restrained eaters also exhibited increase activation in right middle frontal gyrus (MFG) compare to unsuccessful eaters during the working memory task.Main findings of this study are as follows. High-calorie food cues would have negative effect on working memory performance of participants. Restrained eaters have a worse working memory performance than unrestrained eaters. Restrained eaters have a long-term memory bias to food cues. Successful restrained eaters have a better execution to weight-control goal than unsuccessful restrained eaters. This might be the key element to successful eating control.