| On December 23,2020,the State Council Information Office issued the Report on the Nutrition and Chronic Disease Status of Chinese Residents(2020)which suggests that over 50% of Chinese adult residents suffer overweight and obesity and this problem is becoming more prominent.To prevent obesity,more people are going on a diet or exercising in the hope of losing or controlling their weight.Restrained eaters refer to chronic dieters who are with a strong motive to lose weight and try to control food intake.Most restrained eaters are females,because they are very concerned about their weight and body shape.With an increasingly tempting diet environment,they force themselves to avoid eating delicious food.Although restrained eaters are striving to control their desire for diet,most of them are still trapped in a circulation of restrained eating and free eating or even overeating.Those who disinhibit eating behaviors are unsuccessful restrained eaters.On the contrary,those who always practice restrained eating to maintain the goals of weight control become successful restrained eaters.The external food stimuli and the internal executive control are two important aspects which affect whether restrained eaters could keep successful dieting behaviors.Previous studies verified that restrained eaters,in particular,unsuccessful restrained eaters performed weakened inhibition control and working memory toward food stimuli,but lacked systematic researches of cognitive flexibility among them.The purpose of this article is to explore the differences of cognitive flexibility in behavioral and electrophysiological activities among restrained eaters under the Chinese cultural background.Combining self-report,integrated behavior paradigms and the event-related potentials(ERPs),this article consisted of a pre-study and two formal studies.Pre-study conducted standardized appraisal of food materials and neutral materials used in follow-up studies.Formal study 1 discussed behavioral performance in general cognitive flexibility and the electrophysiology indices in food-specific cognitive flexibility between restrained eaters and non-restrained eaters.Formal study 2 discussed behavioral performance in general cognitive flexibility and electrophysiology activity in food-specific cognitive flexibility between successful restrained eaters and unsuccessful restrained eaters.Study 1 consisted of two experiments.Experiment 1 used the Chinese version of Cognitive Flexibility Inventory(CFI)and Wisconsin Card Sorting Test(WCST)to explore the differences in general cognitive flexibility between restrained and non-restrained eaters.No significant between-group differences were found in CFI scores and the four indicators of WCST tasks,which meant no reduction of restrained eating in general cognitive flexibility at the behavior level.Experiment 2 adopted task switching paradigms with two parallel word and image food stimuli combing with ERP techniques to explore the electrophysiological activities of cognitive flexibility between restrained and non-restrained eaters.Behavioral results in picture task switching paradigm revealed larger switch costs in restrained eaters to non-restrained eaters.ERP results revealed that larger P2 amplitudes were observed in food stimuli;compared with non-restrained eaters,restrained eaters exhibited larger N2 amplitudes;both food stimuli and repeated tasks induced larger P3amplitudes;the LPC amplitudes observed a significant increase in repeated tasks.Although there were no food-specific ERP differences between restrained and non-restrained eaters,it could be inferred that in the face of food stimuli,restrained eaters required more cognitive resources to smoothly complete the switch tasks and demonstrated poor cognitive flexibility relating to food trials.The procedures of study 2 were similar to study 1.Study 2 consisted of two experiments and investigated behavioral and electrophysiological differences associated with task switching in a sample of successful restrained eaters and unsuccessful restrained eaters.Experiment 3 using CFI and WCST demonstrated that there were no significant group differences in general cognitive flexibility by self-report and behavioral ways.Experiment 4 adopted two food-related task switching paradigms combining with the ERPs: at the behavior level,smaller switch costs in successful restrained eaters to unsuccessful restrained eaters.At the electrophysiological level,food stimuli exhibited significant P2 amplitudes;the significant increase in N2 amplitudes and reduction in P3 amplitudes bias for food stimuli in unsuccessful restrained eaters;the LPC amplitudes were larger when these two kinds of restrained eaters were executing repeated tasks.The smaller behavioral switch costs in successful restrained eaters showing exhibit superior sustained attention and faster task-set reconfiguration processes compared to unsuccessful restrained eaters,especially toward the processing of food stimuli.The ERP results consistent with behavior results and revealed that unsuccessful restrained eaters performed poor food-specific cognitive flexibility and they were maybe easily committed to overeating during depletion of cognitive resources.To sum up,based on the goal conflict model of eating behavior,this research explored the differences in cognitive flexibility between restrained and non-restrained eaters as well as between successful and unsuccessful restrained eaters.According to behavioral and electrophysiological results,we infer that restrained eating will probably lower an individual’s cognitive flexibility over food,though such differences with normal eating are not significant.In addition,disinhibited eating of restrained eaters will exert significant influences on their cognitive flexibility over food stimulus and lower the reaction flexibility in food choices.The research demonstrated the cognitive flexibility of restrained eaters and their subclass from the two angles of food reward and cognitive function.It is conducive to further understand the cognitive characteristics and the causes of overeating,provided empirical and neural electrophysiology evidence based on previous theoretical model.Furthermore,promoting the development of the studies in this field and providing a new feasible perspective for clinical intervention. |
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