Quantifying the presence of evidential value and selective reporting in food-related inhibitory control training: a p-curve analysis

The impact of exercise on food-related inhibitory control- do calories, time of day, and BMI matter? Evidence from an event-related potential (ERP) study

A growing body of research suggests exercise improves inhibitory control functions. We tested if exercise-related inhibitory control benefits extend to food-related inhibitory control and differ by calorie content, time of day, and weight status. One hundred thirty-eight individuals were pseudo-randomly assigned to a morning or evening group. Each subject participated in two lab sessions where they completed questionnaires (rest session) or walked on a treadmill at 3.8mph (exercise session) for 45 min. After each session, participants completed both a high-calorie and low-calorie go/no-go task while N2 and P3 event-related potentials (ERP), both neural indicators of inhibitory control, were measured. Participants also rated food images for valence and arousal. While N2 and P3 difference amplitudes were larger to high-calorie than low-calorie foods, neither exercise nor time of day affected results. Individuals had faster response times after exercise without decreases in accuracy. Arousal and valence for high-calorie foods were lower after exercise and lower for all foods after morning compared to evening exercise. In a subset of individuals with obesity and normal-weight individuals, individuals with obesity had larger N2 difference amplitudes after morning exercise, while normal-weight individuals had larger P3 difference amplitudes to high-calorie foods after exercise. Results suggest moderate exercise did not affect food-related inhibitory control generally, although morning exercise may be beneficial in improving early recruitment of food-related inhibitory control in individuals with obesity. Moderate exercise, particularly in the morning, may also help manage increased attention allocated to food.

Response inhibition training as an intervention to modify liking and wanting for foods based on energy density: a proof of concept study

The ubiquity of energy-dense, processed foods has been implicated as a salient feature of the modern 'obesogenic' environment. Cognitive strategies, such as response inhibition training, have been demonstrated to reduce the hedonic value of such foods in previous studies. However, this effect has generally been inconsistent or heterogenous, depending on the outcome measure, characteristics of the sample, and the specificity of food stimuli. Characterising the extent of generalised effects may help define the application of this type of intervention in natural settings. A repeated-measures, proof-of-concept study, using mobile app-based response inhibition training (RIT) versus a control app-based activity (N = 25), was undertaken to establish the valid application of a food reward measure to assess intervention efficacy. Liking (i.e., affect) and wanting (i.e., motivation) for food stimuli categorised by energy density were taken concurrently pre- and post-training. A statistically significant reduction in explicit liking, but not implicit wanting, for foods irrespective of their energy density was observed during the RIT app-based training session relative to the control (p = .041, ηp2 = .16). However, effect sizes associated with devaluation of energy-dense relative to low calorie food stimuli, although non-significant, were higher when measured as implicitly wanting (p = .098, ηp2 = .11) than explicit liking (p = .756, ηp2 = .00). Trends in explicit stimulus evaluations were empirically discordant from implicit evaluations for low calorie foods in particular. Additional research is needed to investigate whether these trends are reproducible with larger samples, trained and novel food stimuli in outcome measures, and more comprehensive training protocols.

Can smartphone-based response inhibition training elicit sustained changes in appetite, preference, and cravings for energy-dense foods? A free-living randomized controlled trial

BACKGROUND

Food-specific response inhibition training has been implemented as a strategy to modify food choices and reward-related eating behaviours, but short-term studies have produced equivocal findings.

OBJECTIVE

To longitudinally assess the effect of a smartphone-based response inhibition intervention on food reward, hedonic eating drive, and cravings in a free-living setting.

METHODS

84 adults (Mage  = 30.49, SDage  = 13.01, 52 female) with high responsivity to food cues or overweight/obesity were randomly assigned to a response inhibition training intervention (n = 45) or a control game (n = 39) at home during a training week, followed by a week with no training. Primary analyses compared groups on measures of explicit liking and implicit wanting for food of different energy densities, food cravings, and reward-related eating throughout this two-week period.

RESULTS

A reduction was observed in explicit liking and implicit wanting for energy-dense foods from baseline to post-training independent of condition (ps < .001). These changes from baseline were sustained after a 1-week latency period, also independent of condition (ps < .001). These effects coincided with similar observations of hedonic eating drive, tonic cravings, and control over cravings during the observation period (ps < .01).

CONCLUSIONS

Although significant reductions in reward-related appetite were observed, free-living response inhibition training did not offer additional benefit over a control activity. Future intervention studies with observable food intake are needed to investigate which appetitive mechanisms most reliably predict eating behaviour over time.

TRIAL REGISTRATION

Retrospectively registered with ANZCTR [ACTRN12622001502729].

Neural correlates underlying preference changes induced by food Go/No-Go training

Consistently not responding to appetitive foods during food go/no-go training could change individuals' food choices and sometimes even body weight, however, fewer studies have explored the neural pathways underlying the effects of food go/no-go training. In this study, we scanned eighty-six female participants using functional magnetic resonance imaging and investigated the neural bases of preference changes in a binary food choice task following action (e.g., go) or inaction (e.g., no-go) toward distinct foods within a food go/no-go training paradigm. In line with prior behavioral work, we found that participants' food preferences changed as a function of food go/no-go training, with participants choosing more "go" over "no-go" foods for consumption following training. At a neural level, preference changes were inversely associated with frontoparietal and salience network activity when choosing go (vs. no-go) foods. Additionally, task-related functional connectivities from the inferior parietal lobule to the pre-supplementary motor cortex, dorsolateral prefrontal cortex, and dorsal anterior cingulate cortex were related to these preference changes. Together, current work supports that food go/no-go training reliably changes people's preferences. More importantly, our findings suggest that a neural pathway centered on areas traditionally associated with selective attention may interface with prefrontal regions to guide preference changes induced by food go/no-go training, though future studies using other tasks (e.g., passive viewing tasks) are still needed to test this potential neural mechanism.

Comparing the effects of inhibitory control training and evaluative conditioning for unhealthy food behaviours

Cognitive Bias Modification (CBM) is hypothesised to reduce unhealthy food preference and consumption through the completion of computerised cognitive training tasks. While there is evidence to suggest that two popular CBM paradigms (Inhibitory Control Training (ICT) and Evaluative Conditioning (EC)) can have a positive influence on food-related outcomes, issues (and inconsistencies) related to task standardisation and control group design make it difficult to evaluate their standalone efficacy. In a pre-registered laboratory study using a mixed experimental design, our aim was to directly compare a single session of ICT and EC on implicit preference, explicit choice and ad-libitum food intake, while ensuring appropriate active control groups were utilised for each training type (in addition to a passive control group). The results revealed that there were no significant differences in terms of implicit preferences, ad-libitum food consumption or food choice. These results provide limited evidence to support the use of CBM as a psychological intervention for unhealthy food choice or consumption. Further work is needed to isolate mechanisms of effect for successful training and identify the most effective CBM protocols for implementation in future studies.

Tempest in a teacup: An analysis of p-Hacking in organizational research

We extend questionable research practices (QRPs) research by conducting a robust, large-scale analysis of p-hacking in organizational research. We leverage a manually curated database of more than 1,000,000 correlation coefficients and sample sizes, with which we calculate exact p-values. We test for the prevalence and magnitude of p-hacking across the complete database as well as various subsets of the database according to common bivariate relation types in the organizational literature (e.g., attitudes-behaviors). Results from two analytical approaches (i.e., z-curve, critical bin comparisons) were consistent in both direction and significance in nine of 18 datasets. Critical bin comparisons indicated p-hacking in 12 of 18 subsets, three of which reached statistical significance. Z-curve analyses indicated p-hacking in 11 of 18 subsets, two of which reached statistical significance. Generally, results indicated that p-hacking is detectable but small in magnitude. We also tested for three predictors of p-hacking: Publication year, journal prestige, and authorship team size. Across two analytic approaches, we observed a relatively consistent positive relation between p-hacking and journal prestige, and no relationship between p-hacking and authorship team size. Results were mixed regarding the temporal trends (i.e., evidence for p-hacking over time). In sum, the present study of p-hacking in organizational research indicates that the prevalence of p-hacking is smaller and less concerning than earlier research has suggested.

Pilot study of food-specific go/no-go training for overweight individuals: brain imaging data suggest inhibition shapes food evaluation

Food-specific go/no-go training might reduce overeating and facilitate weight loss. In this pilot study, we examined whether a food-specific go/no-go training over five weeks, as compared to a non-food-specific training, could produce changes in behavioral and neural responses to food images and body weight. Here, we used a sample of 51 overweight participants divided into training and control groups whose brain activity and food evaluation were measured before and after the training. Compared with the control group, in the training group we found significant reductions in high-calorie food evaluation. We also found lower activations in inhibitory control- and reward-related brain regions in response to high-calorie food images. Further, activation change of the mid-insula in response to the high-calorie food images was positively associated with change in the evaluation of those images. However, we found no evidence for a significant effect of food-specific go/no-go training on body weight change. Our findings highlight that food-specific go/no-go training in overweight individuals can reduce high-calorie food evaluation, but also neural activations in inhibitory control- and reward- related brain regions.

A p-curve analysis of the emotional Stroop effect among women with eating disorders

OBJECTIVE

A recent meta-review of attentional bias research in eating disorders suggests that meta-analyses and systematic reviews include many low-quality and underpowered studies (Stott et al., 2021). As such, we examined whether published research examining the link between attentional bias, using the emotional Stroop task, and eating disorders among women with eating disorders has evidential value (ruling out selective reporting of a statistically significant effect) using a p-curve analysis. A p-curve analysis plots statisticall significant p-values onto a curve from .01 to .05 to examine its distribution. We hypothesized that the p-curve would be flat, indicating no true effect.

METHOD

The hypothesis, database search strategy, and data analytic approach were pre-registered. The inclusion criteria were reports that compared control and eating disorder groups, reported inferential statistics, and that used body shape/weight or general threat target words.

RESULTS

Fifty published reports were included in the p-curve analyses. Unexpectedly, the half and full p-curves were significantly right-skewed, indicating evidential value. However, the results were not robust to the exclusion of the seven lowest p-values and on average, reports were underpowered. There were also 18 reports with null results (they had a p-value greater than .05), which precluded their inclusion in the p-curve analyses.

DISCUSSION

The findings suggest that most of the evidence from research examining attentional biases using the emotional Stroop task among women with an eating disorder or with elevated eating disorder symptoms is underpowered and so should be interpreted with considerable caution.

PUBLIC SIGNIFICANCE

Concerns have been raised about the low quality of research examining attentional biases among women with eating disorders using the emotional Stroop task. In the current research, we observed that the evidential value of primary research reporting differences between women with and without eating disorders was equivocal and had low statistical power. These results can guide researchers towards conducting more rigorous research on attentional biases among people with eating disorders.

Exploring acute and non-specific effects of mobile app-based response inhibition training on food evaluation and intake

Previous studies have demonstrated that response inhibition training can modify the appeal of palatable and energy-dense foods, thus serving as a potential intervention for weight management, via changes in food selection and intake. However, empirical findings of efficacy have been inconsistent across studies due to heterogenous approaches to measuring salient appetitive outcomes, training implementation strategies, and sample recruitment. Systematic assessment of both affective and motivational components of food reward may help characterise to what extent devaluation can be generalised to nutritionally similar foods post-training. In this mixed factorial experiment, a non-clinical, adult sample completed time-matched single sessions with mobile app-based response inhibition training and control tasks of short (12 min; n = 27) or long (20 min; n = 25) duration. Participants were assessed on two discrete facets of food reward pre- and post-training: pleasure (i.e., explicit liking) and desire (i.e., implicit wanting) for non-specific (i.e., novel) food stimuli differing in energy-density. Consumption of snacks categorised by energy density was also assessed in a laboratory ad libitum taste test post-training. No significant differences were found between intervention and control sessions on explicit liking or implicit wanting for non-specific energy-dense foods. Moreover, participants ate a similar volume of snack foods during both sessions. Training duration did not significantly moderate differences between intervention and control sessions in primary outcomes. Variance between intervention and control sessions in chocolate intake and frequency of choice for energy-dense foods, but not explicit liking, was associated with a higher BMI. Methodological and theoretical implications for appropriate intervention implementation and underlying mechanisms, respectively, are discussed.

Food-Specific Inhibition Training for Food Devaluation: A Meta-Analysis

Theories have suggested that food-specific inhibition training could lead to food devaluation which, in turn, may help people to regulate their eating behavior. In this review, we have synthesized the current literature on this topic by conducting a meta-analysis of studies investigating the effects of food-specific inhibition training on food evaluation. We identified 24 studies-with 36 independent samples, 77 effect sizes, and 3032 participants-that met our inclusion criteria. Effect sizes were analyzed using the robust variance estimation in random effects meta-regression technique. The results indicate that food-specific inhibition training can lead to statistically significant reductions in food evaluation. More specifically, it was observed that the effects of training on participants' food evaluation differed according to the type of evaluation; food-specific inhibition training significantly decreased participants' explicit food evaluation, but not their implicit food evaluation. However, because most of the included studies focused on trained food items and short-term outcomes in normal-weight samples, more research is needed on the continuance of the training effects, as well as on the extent to which effects can be generalized to untrained food items or different populations (e.g., overweight or obese individuals).

Testing the relationship between inhibitory control and soda consumption: An event-related potential (ERP) study

The intake of sugar-sweetened beverages (SSB) may detrimentally influence health outcomes. Drinking less soda may help manage SSB consumption, as soft drinks are a top contributor to SSB intake. One cognitive factor that may influence soda consumption is inhibitory control, or the ability to withhold a dominant response in order to correctly respond to one's environment. Increased inhibitory control plays a role in decreasing consumption of high-calorie foods, and strengthening inhibitory control may help individuals manage their food intake. However, neural response to soda beverages versus traditional non-sweetened beverages, such as water, and how it relates to soda consumption is unknown. In a sample of 116 healthy individuals (M = 20.56; SD = 2.08; 47.4% female), we measured soda consumption and tested event-related potential (ERP) measures of inhibitory control, including the N2 and P3 components, during soda-specific and neutral comparison go/no-go tasks. Female participants consumed less soda on average than males, and as participants got older, they consumed less soda. Participants showed faster response times and higher accuracy on the soda-specific compared to neutral go/no-go . ERP results indicated inhibitory control was greater when individuals withheld dominant responses to soda stimuli rather than neutral stimuli. Neither N2 no-go amplitude on the soda-specific go/no-go nor P3 no-go amplitude on the soda-specific predicted measures of soda intake. Results suggest greater inhibitory control resources are required when withholding responses to soda beverages compared to neutral stimuli, but inhibitory control ERPs did not predict day-to-day soda intake.

The relationship between acute stress and neurophysiological and behavioral measures of food-related inhibitory control: An event-related potential (ERP) study

Stress influences many health-related behaviors including diet and nutrition intake, often resulting in increased calorie intake, fewer healthy eating behaviors, and poorer nutrition. Food intake is modulated by inhibitory control and has important implications for our physical, mental, and emotional health. Yet, little is known about the relationship between stress and food-related inhibitory control. We tested the influence of a short-term experimental stressor on behavioral and event-related potential (ERP; N2 and P3 components) measures of food-related inhibitory control. Ninety-seven healthy participants were randomly assigned to complete the Trier Social Stress Test (TSST) (n = 48, 27 females [52.9%]) or a neutral control condition (n = 49, 35 females [70%]) immediately followed by food-specific go/no-go and neutral go/no-go tasks while electroencephalogram (EEG) data were recorded. Stress levels were successfully manipulated, with heightened self-report and physiological measures (heart rate and systolic blood pressure) of the stress response in individuals who completed the TSST compared to control. As expected, the high calorie food-specific go/no-go task elicited larger N2 amplitude than the neutral task. N2 component amplitude was also significantly larger following the TSST relative to the control task. There were no significant between-group or task differences for P3 amplitude or behavioral measures. Findings suggest heightened N2 amplitude following psychological stress that is not specific to food or inhibition processes and may reflect heightened arousal following stress. Future research in individuals with overweight/obesity or experiencing chronic stress will further clarify the role of stress in food-related inhibitory control.

Effects of go/no-go training on food-related action tendencies, liking and choice

Inhibitory control training effects on behaviour (e.g. 'healthier' food choices) can be driven by changes in affective evaluations of trained stimuli, and theoretical models indicate that changes in action tendencies may be a complementary mechanism. In this preregistered study, we investigated the effects of food-specific go/no-go training on action tendencies, liking and impulsive choices in healthy participants. In the training task, energy-dense foods were assigned to one of three conditions: 100% inhibition (no-go), 0% inhibition (go) or 50% inhibition (control). Automatic action tendencies and liking were measured pre- and post-training for each condition. We found that training did not lead to changes in approach bias towards trained foods (go and no-go relative to control), but we warrant caution in interpreting this finding as there are important limitations to consider for the employed approach-avoidance task. There was only anecdotal evidence for an effect on food liking, but there was evidence for contingency learning during training, and participants were on average less likely to choose a no-go food compared to a control food after training. We discuss these findings from both a methodological and theoretical standpoint and propose that the mechanisms of action behind training effects be investigated further.

Modifying food items valuation and weight with gamified executive control training

Recent lines of research suggest that repeated executive control of motor responses to food items modifies their perceived value and in turn their consumption. Cognitive interventions involving the practice of motor control and attentional tasks have thus been advanced as potential approach to improve eating habits. Yet, their efficacy remains debated, notably due to a lack of proper control for the effects of expectations. We examined whether a one-month intervention combining the practice of Go/NoGo and Cue approach training modified the perceived palatability of food items (i.e. decrease in unhealthy and increase in healthy food items' palatability ratings), and in turn participants' weights. We assessed our hypotheses with a parallel, double-blind, randomized controlled trial. Motivation and adherence to the intervention were maximized by a professional-level gamification of the training tasks. The control intervention differed from the experimental intervention only in the biasing of the stimulus-response mapping rules, enabling to balance expectations between the two groups and thus to conclude on the causal influence of motoric control on items valuation. We found a larger decrease of the unhealthy items' palatability ratings in the experimental (20.6%) than control group (13.1%). However, we did not find any increase of the healthy items' ratings or weight loss. Overall, the present registered report confirms that the repeated inhibition of motor responses to food cues, together with the development of attentional biases away from these cues, reduces their perceived value.

How can food choice best be trained? Approach-avoidance versus go/no-go training

Behavior toward appetitive stimuli can be changed by motor response training procedures in which participants approach or respond to some stimuli and avoid or inhibit behavior to other stimuli. There is discussion in the literature whether effects are different when participants approach versus avoid stimuli during approach-avoidance training compared to when they respond versus not respond to stimuli during go/no-go training. Here, we directly compared effects of approach-avoidance training and go/no-go training on food choice within the same rigorous experimental protocol. Results showed that both training procedures influence food choice such that participants preferred Approach over Avoidance food items, and Go over NoGo food items, and these training effects were not statistically different. The present work suggests any inconsistencies in the literature on possible differences in effectiveness of these training procedures may be explained by differences in methods employed. The present work also raises new theoretical and applied questions about motor response training as a means to change behavior.

Examining cognitive bias modification interventions for reducing food value and choice: Two pre-registered, online studies

There is considerable interest in Cognitive Bias Modification (CBM) as a potential treatment for overweight/obesity. Inhibitory Control Training (ICT: also known as motor response training) and Evaluative Conditioning (EC) are two popular paradigms which rely on associatively learned responses (unhealthy food - > inhibition, or unhealthy food- > negative stimulus, respectively) through repeated cue-response contingencies. Both ICT and EC have demonstrated some effectiveness for reducing food intake, value and/or choice, when administered in the laboratory and online. However, studies have been criticised for inconsistencies in design (e.g. use of inadequate control groups) which makes it difficult to draw robust conclusions. In two pre-registered, online studies our aim was to examine active ICT (study 1: N = 170) and EC (study 2: N = 300) in multiple groups where the cue- > response contingencies were systematically varied (100%, 75%, 50%, 25%), before examining food-cue valuations and hypothetical food choice. In both studies varying the cue- > response contingencies did not lead to significant changes in food-cue devaluation following training. ICT did not substantially influence hypothetical food choice, whereas there was weak evidence that EC reduced choice for unhealthy foods, compared to a control group with 50% cue-response contingencies. Taken together both studies provide limited evidence for online CBM as a viable psychological treatment - at least through the mechanism of food-cue devaluation or changes in healthy and unhealthy food choice. Future research is needed to investigate the factors that contribute towards successful CBM training to critically evaluate the potential for these strategies within interventions.

Go/no-go for food: Attention bias and intention to eat unhealthy food

OBJECTIVE

The current research evaluated whether Go/No-go training for highly palatable (HP) food affected attention bias for HP food (an automatic/implicit outcome) and intention to eat unhealthy food (a controlled/explicit outcome).

METHOD

A sample of Australian adults representative for age, gender and Body Mass Index (BMI) (N = 561, M_age = 46.31 years, SD = 16.75, 52.3% women, M_BMI = 27.11, SD = 6.34) completed self-report measures of dietary psychological constructs and food image modified Stroop tasks as measures of pre- and post-test attention bias for HP food. After random assignment of participants to two conditions, a Go/No-go intervention was used to train HP food targeted inhibitory control in the experimental group, or general inhibitory control in the control group. All research tasks were delivered online.

RESULTS

The experimental, HP food inhibitory control training group reported intention to eat less unhealthy food than the control group, F (1, 637) = 4.81, R² = 0.09, p = .029. Counter to expectations, the experimental group exhibited a heightened attention bias to HP food images after the training, F (1, 637) = 9.48, R² = 0.39, p = .002.

CONCLUSION

Go/No-go training for food may improve both top-down and bottom-up inhibitory control, using both automatic and controlled processes. Further, it may not be effective in lowering attention bias for HP food, but may be effective in lowering unhealthy food intake despite raising attention bias for HP food. Further research that tests these effects using varied reaction time tasks is needed to confirm these results and to explore possible alternative explanations.

Publication and related biases in health services research: a systematic review of empirical evidence

Background

Publication and related biases (including publication bias, time-lag bias, outcome reporting bias and p-hacking) have been well documented in clinical research, but relatively little is known about their presence and extent in health services research (HSR). This paper aims to systematically review evidence concerning publication and related bias in quantitative HSR.

Methods

Databases including MEDLINE, EMBASE, HMIC, CINAHL, Web of Science, Health Systems Evidence, Cochrane EPOC Review Group and several websites were searched to July 2018. Information was obtained from: (1) Methodological studies that set out to investigate publication and related biases in HSR; (2) Systematic reviews of HSR topics which examined such biases as part of the review process. Relevant information was extracted from included studies by one reviewer and checked by another. Studies were appraised according to commonly accepted scientific principles due to lack of suitable checklists. Data were synthesised narratively.

Results

After screening 6155 citations, four methodological studies investigating publication bias in HSR and 184 systematic reviews of HSR topics (including three comparing published with unpublished evidence) were examined. Evidence suggestive of publication bias was reported in some of the methodological studies, but evidence presented was very weak, limited in both quality and scope. Reliable data on outcome reporting bias and p-hacking were scant. HSR systematic reviews in which published literature was compared with unpublished evidence found significant differences in the estimated intervention effects or association in some but not all cases.

Conclusions

Methodological research on publication and related biases in HSR is sparse. Evidence from available literature suggests that such biases may exist in HSR but their scale and impact are difficult to estimate for various reasons discussed in this paper.

Systematic review registration

PROSPERO 2016 CRD42016052333.

Quantifying evidential value and selective reporting in recent and 10-year past psychophysiological literature: A pre-registered P-curve analysis

Selective reporting (i.e., only reporting significant findings as opposed to all analyses or results) is a questionable research practice that undermines the integrity of published research. Psychophysiology research may be susceptible to selective reporting, given the high number of decision points and methodological complexity in analyses of psychophysiology data. We aimed to assess the presence of selective reporting and evidential value (i.e., that significant results are due to true underlying effects) in recent and past psychophysiological research by utilizing p-curve analyses. Study protocols and methods were pre-registered on the Open Science Framework (OSF). P-values and the associated test statistics were extracted from articles in the most recent issue (as of January 2018) and 10-year previous counterpart issue of three major psychophysiology journals: Psychophysiology, International Journal of Psychophysiology, and Journal of Psychophysiology. Using the p-curve application, 10 primary p-curves were conducted: all recent articles, all past articles, recent articles split by journal, past articles split by journal, recent cognitive electrophysiology articles, and past cognitive electrophysiology articles. Evidential value and generally adequate average power (≥78% average power) were present in all p-curves, except those that only included articles from the Journal of Psychophysiology because of the small number of articles published in the journal. Findings provide some positive news and indicate that, generally, results were not selectively reported, and selective reporting may not be a primary issue for this sample of psychophysiological research. Future p-curve analyses examining sub-disciplines of psychophysiology are recommended.