Automatic approach/avoidance tendencies towards food and the course of anorexia nervosa

Persistent avoidance of virtual food in anorexia nervosa-restrictive type: Results from motion tracking in a virtual stopping task

OBJECTIVE

Food avoidance is central to patients with anorexia nervosa-restrictive type (AN-R). Competing accounts in experimental psychopathology research suggest that food avoidance may result from automatic, habitual responses or from elevated inhibitory control abilities. This study investigated behavioral trajectories of food avoidance in a novel virtual reality stopping task.

METHOD

Sixty patients with AN-R and 29 healthy controls with normal weight were investigated using a novel, kinematic task in virtual reality. We recorded spatial displacement in stop- and go-trials to virtual food and control objects. Inhibitory control abilities were operationalized by the VR task in stopping performance (i.e., interrupted movement in stop-trials), whereas we also measured habitual avoidance of virtual food across both go- and stop-trials (i.e., delayed movement relative to nonfood objects).

RESULTS

In patients with AN-R, hand displacements were shorter to food versus nonfood across stop- and go-trials, reflected in a Stimulus × Group interaction. Healthy controls showed no differences. Importantly, the food-specific effect in AN-R was identical across stop- and go-trials, indicating habitual food avoidance. Moreover, stop error rates (i.e., stop-trials with response) were lower in patients with AN-R.

DISCUSSION

The findings suggest food-specific habitual avoidance and heightened generalized inhibitory control in AN-R. The continuously delayed displacements during active hand movements across stop- and go-trials indicated the persistence of patients' avoidance of food.

PUBLIC SIGNIFICANCE

Experimental research investigates the mechanisms underlying mental disorders such as anorexia nervosa. In this study, we measured interrupted hand movements in response to food pictures or neutral pictures (shoes) in patients with anorexia nervosa and healthy controls. A virtual reality scenario was used. Findings indicated that patients were slower at approaching food, interrupted or not. Key mechanisms of food avoidance can be translated into habit-based treatment options in future research.

Food induced distractibility in restrictive anorexia nervosa: Different motor patterns for different foods as revealed by a mouse tracker evaluation

An altered automatic processing of food stimuli may contribute to the maintenance of calorie restriction in patients with restrictive Anorexia Nervosa (AN-R). The present study aimed to assess whether task-irrelevant food distractors elicited a different interference effect in the motor actions of patients with AN-R compared to healthy controls (HC). 40 patients with acute AN-R and 40 HC performed an irrelevant distractor task in which they were required to perform a reaching movement from a starting point to a green dot, while an irrelevant distractor (a high-calorie food, low-calorie food, or neutral object) was presented in the middle of the screen. Mouse trajectories and response times (RT) were recorded. The analyses conducted on the kinematic variables revealed that while the trajectories of HC veered similarly toward the three categories of stimuli, AN-R patients showed an increased deviation toward low-calorie foods and a reduced deviation toward high-calorie foods compared to neutral objects. No significant results emerged as regards RT. The pattern of responses observed in patients with AN-R (deviation increased toward low-calorie and reduced toward high-calorie) is consistent with their eating habits and may thus represent an implicit mechanism sustaining calorie restriction in patients with AN-R.

Testing the effectiveness of a mobile approach avoidance intervention and measuring approach biases in an ecological momentary assessment context: study protocol for a randomised-controlled trial

INTRODUCTION

Unhealthy eating behaviour is a major contributor to obesity and related diseases and is associated with a behavioural bias to approach rather than avoid desired foods, as measured with reaction time tasks. Approach-avoidance interventions (AAIs) have been proposed as a way to modify food evaluations and help people to eat in accordance with their dietary goals. Mobile implementations of AAI might be easily accessible, low threshold interventions, but their effectiveness has not been established yet.

METHODS AND ANALYSIS

Participants who aim to change their eating behaviour are randomised to intervention or control groups. They complete six sessions of a smartphone-based AAI, in which they push (ie, avoid) or pull (ie, approach) personalised food images. Intervention group participants always avoid foods that they personally want to eat less often and approach foods that they personally want to eat more often. In the control group, images are paired equally often with both response directions. To evaluate contextual and dynamic intervention effects, ecological momentary assessment (EMA) is measured throughout, with questions about food intake, hunger, stress, emotions, eating intentions, food craving and impulsivity twice a day. Additional EMA preintervention and postintervention measures are administered before and after the intervention phase (4 days each) with a 1-day follow-up EMA 4 weeks after the intervention. Multilevel models will examine the temporal covariance between approach bias and self-reported variables as well as short-term and long-term intervention effects on approach bias, food intake and craving.

ETHICS AND DISSEMINATION

The study was approved by the Ethics Committee of the University of Salzburg. Results will be published in peer-reviewed scientific journals and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register DRKS, registration number DRKS00030780.

Touchscreen-based approach-avoidance responses to appetitive and threatening stimuli

BACKGROUND AND OBJECTIVES

Individuals are thought to be biased towards approaching positive stimuli and avoiding negative stimuli. Yet, it is unclear whether this general pattern applies to all stimulus classes or whether biases are more specific. We expected significant approach biases towards two types of positive stimuli, appetitive foods and butterflies; and avoidance biases away from two types of negative stimuli, spoiled foods and spiders.

METHODS

A touchscreen-based Approach-Avoidance Task (AAT), using hand gestures toward or away from stimuli assessed biases. Questionnaires and image ratings assessed individual differences in stimulus evaluations.

RESULTS

Approach biases for butterflies and appetitive foods were found, the latter being strongest towards individually liked foods. There was no avoidance bias for spoiled foods. An avoidance bias for spiders was found in individuals with elevated spider fear.

LIMITATIONS

Incomplete counterbalancing precluded direct comparison between both positive and negative stimuli.

CONCLUSIONS

Behavioural biases in the touchscreen AAT generally co-vary with individuals' affective evaluation of the stimuli. Approach biases were elicited by positive stimuli independently of whether they were regularly (foods) or rarely (butterflies) approached in everyday life. This may hint towards a tendency to approach positive stimuli regardless of the specific category, whereas avoidance biases may be more stimulus specific.

Implicit approach-avoidance tendencies toward food and body stimuli absent in individuals with anorexia nervosa, bulimia nervosa, and healthy controls

OBJECTIVE

Body and food-related information are thought to activate cognitive biases and contribute to the maintenance of eating disorders (ED). Approach-avoidance biases may play an important role in the maintenance of dietary restriction and excessive food intake. Therefore, the present study aimed to examine approach-avoidance biases toward food and body stimuli in individuals with anorexia nervosa (AN), bulimia nervosa (BN), and healthy controls (HC).

METHODS

The study included 42 individuals with AN, 24 individuals with BN, and 38 HCs. We used two implicit Approach-Avoidance Tasks (AAT) to assess approach-avoidance biases: participants completed a Food-AAT (high-calorie vs. low-calorie food) and a Body-AAT (thin vs. normal weight bodies). Additionally, explicit ratings of food and body stimuli were assessed.

RESULTS

There were no significant Group × Stimulus × Direction interactions in the implicit Food-AAT or implicit Body-AAT. In explicit ratings, individuals with AN and BN reported less urge to eat and more regret if they ate high-calorie and low-calorie food; individuals with AN and BN rated normal weight bodies as less normal weight, less attractive and less desirable than HCs. There were no group differences in explicit ratings of the thin body.

DISCUSSION

We did not find evidence for biased approach-avoidance tendencies toward food or body stimuli in individuals with AN or BN. Future studies are necessary to understand conflicting findings regarding approach-avoidance biases toward food and body stimuli in individuals with ED.

Touchscreen-based assessment of food approach biases: Investigating reliability and item-specific preferences

Strong cravings for unhealthy foods and implicit tendencies to approach them threaten the physical and mental health of vulnerable populations. Yet, implicit measures of food approach tendencies have methodological limitations, as existing approach-avoidance tasks (AAT) are often unreliable and require specialized hardware. We propose a novel method to measure approach biases: on a touchscreen, participants slide their hand either toward a food item (and away from control images) or away from it (and toward control images) in separate blocks. Adequate attention to the stimuli is ensured by the coupling of stimulus category to the required response. We found that this touchscreen-variant of the AAT yielded reliable bias scores when approach and avoidance were defined as movements relative to the stimulus rather than to the body. Compared to control images, we found an approach bias for low-calorie foods but not for high-calorie foods. This bias additionally varied on a food-by-food basis depending on the participant's desire to eat individual food items. Correlations with state and trait cravings were inconclusive. Future research needs to address the order effects that were found, in which participants avoiding foods in the first block showed larger biases than participants approaching food in the first block, likely due to insufficient opportunity to practice the task. Our findings highlight the need for approach bias retraining paradigms to use personalized stimulus sets. The task can enrich the methodological repertoire of research on eating disorders, obesity and cognitive bias modification.

Food approach bias is moderated by the desire to eat specific foods

In a post-scarcity world, energy intake and excesses therein are mediated by psychological mechanisms, such as implicit inclinations to approach certain foods. We investigated how food deprivation, calorie content and individual food preferences affect this approach bias. Sixty women performed a touchscreen-based approach-avoidance task featuring a wide range of food items, once while satiated and once while food-deprived for 15 h. We found an overall approach bias towards food that was not influenced by food deprivation or calorie density of the food items. Instead, we found that approach bias related to the participants' (lack of) desire to eat specific food items, and to a lesser extent to how much their general desire to eat changed due to food deprivation. Links with food preference were selective to trials in which foods had to be approached, and were absent in trials in which foods had to be avoided, pointing to selectivity to appetitive brain systems and clarifying the nature of the bias. Approach bias was unrelated to overall state or trait food craving. We conclude approach bias for appetitive stimuli may primarily express itself as speeded approach rather than slowed avoidance. Additionally, our results show there is merit in personalizing stimulus selection for approach bias measurement and retraining, as approach bias was concordant with individual food preferences, rather than objective calorie content.

A personalized approach-avoidance modification intervention to reduce negative body image. A placebo-controlled pilot study

BACKGROUND AND OBJECTIVES

Drive for thinness is considered an important factor in the onset and maintenance of negative body image and can be conceptualized as a motivational approach tendency towards thin bodies. The goal of this study was to test whether training thinness-related approach-avoidance tendencies is effective in improving body satisfaction using a personalized training with individuals' own body pictures.

METHODS

Undergraduate women scoring high on drive for thinness (N = 104) were randomly assigned to an experimental, placebo or no training control condition. The experimental training consisted of four training sessions in which participants pushed away thin versions of their own body pictures and pulled closer realistic pictures of themselves. The same stimuli were shown with 50/50 contingency in the placebo training.

RESULTS

The experimental training procedure did not show an effect on self-reported body satisfaction or drive for thinness after one session, four sessions, or one week later. While reaction time indices suggested a marginally significant change in approach-avoidance tendencies in the expected direction, this effect may have been driven by relatively strong thin-approach tendencies in the experimental condition before the start of the training.

LIMITATIONS

High error rates limit the interpretability of the effects on approach-avoidance tendencies. Selection was based on a single item assessing drive for thinness.

CONCLUSIONS

Taken together, our study did not provide evidence that training approach-avoidance tendencies is effective in improving negative body image.

The Influence of Sexual Arousal on Self-Reported Sexual Willingness and Automatic Approach to Models of Low, Medium, and High Prior Attractiveness

Anecdotal evidence suggests that sexual attraction is flexible, and that high levels of sexual arousal can promote sexual willingness and approach tendencies toward a priori low attractive mates. This experimental study tested whether heightened sexual arousal can lower the threshold for sexual willingness and automatic approach tendencies toward potential sex partners of low and medium attractiveness. Heterosexual male (n =54) and female (n =61) participants were randomly assigned to a sexual arousal or control condition. Approach tendencies were indexed using a reaction time task. Sexual willingness was indexed using participant ratings of willingness to kiss and to consider having sex with same- and other-sex models of low, medium, and high attractiveness. Overall, participants showed stronger approach to models of high and medium than of low attractiveness. Sexual arousal weakened this differential responding but did not result in a robust increase of approach toward less attractive other-sex or same-sex models. Sexual willingness toward less attractive models was not affected by sexual arousal. Independent of condition, women reported greater sexual willingness toward same-sex models. The current pattern of findings does not support the notion that sexual arousal promotes automatic approach and sexual willingness to a broader array of sex partners.

The Implicit Association of High-Fat Food and Shame Among Women Recovered From Eating Disorders

BACKGROUND

Despite the growing literature about recovery from eating disorders (EDs), it is still unknown if women who report being recovered from EDs present with differing implicit attitudes about high-fat (vs. low-fat) food relative to women who report having a current ED and women who report never having had an ED.

METHODS

Female volunteers (N = 2,785) to the Project Implicit Mental Health (PIMH) website (https://implicit.harvard.edu/) were divided into three ED groups: current ED (n = 335), prior ED (n = 393), and healthy controls (n = 1,843). Participants completed, between 2016 and 2017, a background questionnaire, together with the Implicit Association Test (IAT), measuring implicit associations between high-fat (vs. low-fat) food and shame (vs. acceptableness). Linear regression models were conducted to examine cross-sectional differences between groups.

RESULTS

Women with prior EDs had stronger implicit associations relative to healthy controls (p = 0.041) and similar implicit associations relative to women with current EDs (p = 0.424).

DISCUSSION

The implicit association between high-fat food and shame may not diminish over time among women with EDs. Future longitudinal studies are warranted to clarify whether an experience of EDs may leave a "scar," manifested in specific implicit associations, that may potentially lead to recurrence after remission.

Moving towards specificity: A systematic review of cue features associated with reward and punishment in anorexia nervosa

Models of anorexia nervosa (AN) posit that symptoms are maintained through deficient reward and enhanced punishment processing. However, theoretical and empirical inconsistencies highlight the need for a more nuanced conceptualization of this literature. Our goal was to comprehensively review the research on reward and punishment responding in AN from a cue-specific lens to determine which stimuli evoke or discourage reward and punishment responses in this population, and, ultimately, what properties these rewarding and punishing cues might share. A systematic review interrogating reward and punishment responses to specific cues yielded articles (n = 92) that examined responses to disorder relevant (e.g., food) and irrelevant (e.g., money) stimuli across self-report, behavioral, and biological indices. Overall, in most studies individuals with AN exhibited aversive responses to cues signaling higher body weights, social contexts, and monetary losses, and appetitive responses to cues for weight loss behaviors and thinness. Findings were more mixed on responses to palatable food and monetary gains. Results highlight that reward and punishment responding in AN are context specific and may be affected by varied stimulus qualities (e.g., predictability, controllability, delay, effort). Increasing specificity in future research on reward and punishment mechanisms in AN will better inform development of precisely-targeted interventions.

How interindividual differences shape approach-avoidance behavior: Relating self-report and diagnostic measures of interindividual differences to behavioral measurements of approach and avoidance

Responding to stimuli in ambiguous environments is partially governed by approach-avoidance tendencies. Imbalances in these approach-avoidance behaviors are implicated in many mental disorders including anxiety disorders, phobias and substance use disorders. While factors biasing human behavior in approach-avoidance conflicts have been researched in numerous experiments, a much-needed comprehensive overview integrating those findings is missing. Here, we systematically searched the existing literature on individual differences in task-based approach-avoidance behavior and aggregated the current evidence for the effect of self-reported approach/avoidance traits, anxiety and anxiety disorders, specific phobias, depression, aggression, anger and psychopathy, substance use and related disorders, eating disorders and habits, trauma, acute stress and, finally, hormone levels (mainly testosterone, oxytocin). We highlight consistent findings, underrepresented research areas and unexpected results, and detail the amount of controversy between studies. We discuss potential reasons for ambiguous results in some research areas, offer practical advice for future studies and highlight potential variables such as task-related researcher decisions that may influence how interindividual differences and disorders drive automatic approach-avoidance biases in behavioral experiments.

The Reciprocal Relationship Between Sexual Arousal and Disgust as Evidenced in Automatic Approach-Avoidance Behavior

Sexual encounters imply exposure to stimuli that in other contexts typically elicit disgust-induced avoidance. To explain why people nevertheless tend to show sexual approach, it has been proposed that heightened sexual arousal may temporarily inhibit disgust. In line with this, studies have found that sexually aroused individuals showed heightened willingness to approach disgusting stimuli. Because automatic processes are critically involved in sexual behaviors, we examined whether the impact of sexual arousal extends to automatic responses to disgust-elicitors. To test the proposed reciprocal relationship between sex and disgust, we also investigated whether disgust reduces automatic sexual approach. In Study 1, 116 female participants (M = age 19.53) were assigned to a sexual arousal or control condition and performed a speeded approach-avoidance task to assess automatic responses to disgusting stimuli. In Study 2, 174 female participants (M = age 22.14) were assigned to a disgust, sexual arousal, or control condition and performed an approach-avoidance task involving both sex and disgust-relevant stimuli. Sexual arousal did not affect automatic responses to disgusting stimuli, and disgust did not influence automatic responses towards sexual stimuli. The reciprocal relationship between sexual arousal and disgust that was previously found for controllable responses did not extend to automatic responses.

Reduced automatic approach tendencies towards task-relevant and task-irrelevant food pictures in Anorexia Nervosa

BACKGROUND AND OBJECTIVES

Anorexia Nervosa (AN) patients are characterized by an excessive restriction of their food-intake. Prior research using an Affective Simon Task (AST) with food as a task-irrelevant feature, provided evidence for the view that AN patients' ability to refrain from food is facilitated by reduced automatic approach tendencies towards food. However, because food was task-irrelevant (i.e., participants had to base their reaction on the perspective of the picture and not on its content), the findings may in fact reflect a relatively strong ability to ignore the content of the food stimuli rather than weakened approach towards food per se. Therefore, this study also included a Stimulus Response Compatibility (SRC) task with food as task-relevant feature that could not be ignored, because the required response depended on the [food vs non-food] content of the pictures.

METHODS

AN spectrum patients (n = 63), and a comparison group of adolescents without eating pathology (n = 57) completed both a SRC task with food as task-relevant feature, and an Affective Simon Task AST with food as task-irrelevant feature.

RESULTS

AN patients showed reduced approach tendencies for high caloric food. Only the SRC uniquely predicted the presence of AN.

LIMITATIONS

Comparison between tasks was hampered because the SRC only included high caloric food stimuli, whereas the AST included high and low caloric food stimuli.

CONCLUSION

Patients with AN are characterized by weakened automatic approach of high caloric food. This might 'help' restrict their food-intake even in a condition of starvation.

The Approach Behavior to Angry Words in Athletes-A Pilot Study

An increasing number of studies have found that athletes have a higher level of aggression than non-athletes. Anger is an important factor in the generation of aggressive behavior, and anger has been found to relate to both approach behavior and avoidance behavior. The present pilot study compared the aggression level of athletes and non-athletes using the Buss-Perry Aggression Questionnaire, and examined the responses of participants to anger-related stimuli using the manikin task, a paradigm that measures approach-avoidance behavior. In total, 15 athletes and 15 non-athletes finished the questionnaire and the manikin task, which included two conditions. In the anger approach condition, participants were asked to approach anger-associated words and to avoid neutral words. The instructions for the anger avoidance condition were the opposite (i.e., move away from the anger-associated words and toward the neutral words). Brain activity was recorded during the manikin task. Results showed that, compared with non-athletes, athletes had significantly higher physical aggression on the questionnaire. The athlete group showed significantly shorter reaction times in anger approach condition than anger avoidance condition. Theta oscillation activity induced during the anger approach condition was significantly lower than that during the anger avoidance condition in the athlete group. No significant correlation was found in present pilot study. These findings may suggest that when anger-related stimuli are present, athletes are more likely to approach, indicating stronger behavioral approach motivation that may result in aggressive behavior.

Can People Accurately Estimate the Calories in Food Images? An Optimised Set of Low- and High- Calorie Images from the food-pics database

Calorie intake plays an important role in maintaining a healthy weight. As such, researchers often use the calorie content of food as a distinction when investigating appetite related brain processes and eating behaviour. This distinction assumes that observers accurately perceive caloric content. However, there is evidence suggesting this is not always the case. The current study examined how accurately observers could estimate the caloric content of food images from the widely used "Food-pics" database. Eight hundred and forty psychology undergraduate students (aged 16-60, 64% female) estimated the caloric value of 178 high and 182 low calorie foods. Calorie content of food from both categories was significantly overestimated. Additionally, 7.7% of low calorie images were misperceived as being high calorie images and 35% of high calorie images were misperceived as being low calorie foods. Neither participants' gender, nor the recognisability and likability of the food images, influenced calorie estimation. Our findings show that most people are unable to accurately estimate caloric content of most food. Despite this, a selection of food images were judged accurately, and we advocate the use of these in research where it is important to have low- and high-calorie food images. Specifically, we propose an optimised stimulus set of 25 high and 25 low calorie food images that are accurately judged by adult participants. In addition, we provide the open source dataset of our ratings of Food-pics images which, when added to the existing Food-pics attributes, creates an enhanced tool for researchers selecting food stimuli.

Cognitive Neuroscience of Eating Disorders

Anorexia nervosa and bulimia nervosa are characterized by severely restricted intake, binge eating, and compensatory behaviors like self-induced vomiting. The neurobiological underpinnings of these maladaptive behaviors are poorly understood, but the application of cognitive neuroscience and neuroimaging to eating disorders has begun to elucidate their pathophysiology. Specifically, this review focuses on 3 areas that suggest paths forward: reward, cognitive and behavioral control, and decision making. Understanding the brain-based mechanisms that promote and maintain these often chronic symptoms could guide the development of new and more effective treatments.

What can food-image tasks teach us about anorexia nervosa? A systematic review

A salient feature of anorexia nervosa (AN) is the persistent and severe restriction of food, such that dietary intake is inadequate to maintain a healthy body weight. Experimental tasks and paradigms have used illness-relevant stimuli, namely food images, to study the eating-specific neurocognitive mechanisms that promote food avoidance. This systematic review, completed in accordance with PRISMA guidelines, identified and critically evaluated paradigms involving images of food that have been used to study AN. There were 50 eligible studies, published before March 10th 2018, identified from Medline and PsychINFO searches, and reference screening. Studies using food image-based paradigms were categorised into three methodologic approaches: neuropsychology, neurophysiology, and functional magnetic resonance imaging (fMRI). Paradigms were reviewed with a focus on how well they address phenomena central to AN. Across tasks, differences between individuals with AN and healthy peers have been identified, with the most consistent findings in the area of reward processing. Measuring task performance alongside actual eating behaviour, and using experimental manipulations to probe causality, may advance understanding of the mechanisms of illness in AN.

Explicit and Implicit Approach vs. Avoidance Tendencies towards High vs. Low Calorie Food Cues in Patients with Obesity and Active Binge Eating Disorder

Patients with binge eating disorder (BED) suffer from regular food binges with loss of control. This may be due to dysfunctional approach vs. avoidance tendencies towards food in BED. We applied an approach-avoidance task (AAT), in which n = 24 patients with obesity and active BED (OB-BED), n = 32 patients with obesity without current BED (OB), and n = 25 healthy controls (CO) either approached (“pulled”) or avoided (“pushed”) high (HC) vs. low calorie (LC) food pictures. We tested the hypothesis that OB-BED patients would show an approach bias (measured as different response times RT) towards HC food compared to the other groups. While there was no main effect for group or direction of movement, a significant main effect for calorie (p < 0.001; RT for HC significantly slower than for LC) was found. Repeated measures ANOVA (rm-ANOVA) for comparison of OB-BED vs. OB vs. CO revealed a significant three-fold interaction group × direction × calorie (p = 0.02). Against our hypothesis, the OB-BED group showed an avoidance bias for LC. In explicit ratings, OB-BED reported a significantly reduced urge to consume LC food compared to the OB group. Similar to OB-BED, CO also showed an avoidance bias for LC. The implications of our results are discussed and future directions in this field of research are presented.

Behavioral Bias for Food Reflected in Hand Movements: A Preliminary Study with Healthy Subjects

Palatable food induces general approach tendencies when compared to nonfood stimuli. For eating disorders, the modification of an attention bias toward food was proposed as a treatment option. Similar approaches have been efficient for other psychiatric conditions and, recently, successfully incorporated approach motivation. The direct impact of attentional biases on spontaneous natural behavior has hardly been investigated so far, although actions may serve as an intervention target, especially seeing the recent advances in the field of embodied cognition. In this study, we addressed the interplay of motor action execution and cognition when interacting with food objects. In a Virtual Reality (VR) setting, healthy participants repeatedly grasped or warded high-calorie food or hand-affordant ball objects using their own dominant hand. This novel experimental paradigm revealed an attention-like bias in hand-based actions: 3D objects of food were collected faster than ball objects, and this difference correlated positively with both individual body mass index and diet-related attitudes. The behavioral bias for food in hand movements complements several recent experimental and neurophysiological findings. Implications for the use of VR in the treatment of eating-related health problems are discussed.