The Impact Of Negative Affect On Food-related Memory Suppression:Evidence From Behavioral And ERP Studies

Memory suppression refers to the intervention of active inhibition of memory,which leads to subsequent forgetting.Different from the previous view that forgetting is a “memory failure”,it focuses on the process and mechanism of how people actively,purposefully,and directionally forget some some unwanted events and information.The classical paradigm of memory suppression is the Think/No-Think(TNT)task,in which researchers mainly investigate the influence of external instructions during the memory extraction phase,and which eventually affected memory.In the memory extraction stage,stopping the extraction of memory would destroy the connection of cues and memory.The continuous effect will affect the availability of the memory in the future.In the field of diet research,scholars have found that memory inhibition can affect people's sensitivity to food clues and prevent people from over-eating and obesity.Emotional eating refers to the behavioral tendency of eating under negative affect,such as people in sadness,anxiety,or anger state.Studies have found that emotional eating is due to emotional deprivation of self-control resources,resulting in reduced control of diet,which causes excessive eating.Regarding the study of emotional eating and cognitive factors,researchers often use Go/No-Go paradigm and Stop Signal paradigm to explore the effect of negative affect on food-related behavioral inhibition control.There few studies investigating the relationship between negative affect and food-related cognitive inhibition control.Consequently,based on the Think/No-Think paradigm,this study explores whether and how negative affects influence food-related memory suppression.Experiment 1 used the self-reporting method to measure the negative emotionalstate of the subjects,used the TNT paradigm to investigate their memory suppression abilities,and used food vocabulary as the target words for the subjects to extract or suppress,to explore the effect of self-reported negative affect on food-related memory suppression.The 57 female undergraduate with normal weight were selected using a 2(negative affect category: high negative affect group,low negative affect group)× 3(experimental conditions: Think,No-think,Baseline)mixed experimental design.The negative affect category is inter-group variable,and the experimental condition is intra-group variable.The results showed that the score of self-reported negative affect was negatively correlated with the score of food-related memory suppression;There was a significant difference between the high and low negative affect groups,and the high negative affect group scored significantly lower than the low negative affect group;The interaction between the negative affect category and the experimental conditions was significant.Specially,in the no-think experimental condition,the recall accuracy rate of the high negative affect was significantly higher than that of the low negative affect group,and in the think and baseline conditions,there was no significant difference in recall accuracy between high and low negative affect groups.The results support our hypothesis that negative affect has a negative effect on food-related memory suppression.The higher the negative affect,the higher the individual's recall rate under no-think conditions,and the worse the food-related memory suppression ability.Experiment 2 used video clips to induce participants' negative affect,neutral affect as control group,to explore the effect of induced negative affect on food-related memory suppression and its ERP evidence.The 50 female undergraduate with normal weight were selected using a 2(affect category: negative affect group,neutral affect group)× 3(experimental conditions: Think,No-think,Baseline)mixed experimental design.The affect category is inter-group variable,and the experimental condition is intra-group variable.The results showed that after watching video clips,there were more sadness scores for negative affect group and no significant different for neutral affect group's sadness and happiness scores.However,there was no significant difference between the negative and neutral affect group in memory suppression scores,and the interaction between affect category and experimental conditions was not significant.The results were inconsistent with the assumptions,maybe due to long experiment and the fatigue of the two groups overwhelming the inducing effect of the video clips.In the ERP results,we selected N1(80-150ms),P2(160-290ms),N2a(280-380ms),P3(360-440ms),N2b(420-500ms)and LPP(480-580ms)based onprevious studies and wave charts.The results showed that(1)the N1 amplitude of the negative affect group was significantly larger than that of the neutral affect group,indicating that the negative affect group had negative affect bias in the early processing;(2)the P2 amplitude of the negative affect group was significantly larger than that of the neutral affect group,indicating that attention of the negative affect group was more involved than that of the neutral affect group;(3)the N2 a amplitude of the negative affect group in frontal region was significantly greater than that of the neutral affect group,indicating more conflict monitoring in the early stages of cognitive processing;(4)the P3 amplitude of the negative affect group was significantly greater than that of the neutral affect group,indicating that negative affect increased the attention resources and occupied the attention resources of the cognitive process;(5)the N2 b amplitude of the negative affect group was significantly lower than that of the neutral affect group,indicating that negative affect caused the reduced ability to suppress memory extraction;(6)the LPP amplitude of the negative affect group was significantly larger than that of the neutral affect group,indicating that the negative affect group was more precise in coding the food-related words and less effective in suppressing memory extraction.As the above two experiments,this study found that negative affect have negative effects on food-related memory inhibition.In the early and middle processing,the negative affect causes the negative affect bias and deepens the individual's processing degree of affect and reflective conflict monitoring.In the late processing,negative affect hinder the individual's inhibition of target memory extraction.Therefore,the recall of food cues is deeper than that of neutral emotional group.This study is innovative in the following aspects: Firstly,the experimental materials selected in this study are all food vocabulary.For the first time,the TNT paradigm of memory inhibition is applied to diet.Secondly,this study uses self-report method to measure emotional state and laboratory evoked method to induce negative emotions,and examines the effects of negative emotions on food cue memory inhibition from different perspectives.Finally,this study provides behavioral and ERP evidence for the effect of negative emotions on food cue memory inhibition.