Relationship between attentional bias and stimulus control: An observational study of real-world eating patterns.

BACKGROUND: Attentional bias towards food related stimuli has been proposed as a potential target for dieting intervention, however the evidence supporting a relationship between attentional bias and food intake is mixed. Theory holds that food related attentional bias should be positively associated with measures of stimulus-controlled eating, and that implicit processes such as impulsivity moderate this association. The aim of the present study was to examine whether the proposed relationship between food-related attentional bias and stimulus control exists, and whether it is moderated by impulsivity. METHOD: A community sample of 68 participants completed a food-related attentional bias task and impulsiveness scale during a laboratory visit, after which they recorded their real-world eating in real-time over 14 days using Ecological Momentary Assessment (EMA). During this time, participants also responded to 4-5 randomly timed assessments per day. Food outlet presence (e.g., fast food restaurants, cafes, corner stores etc.) was assessed during both eating and non-eating assessments. EMA data was then used to determine levels of stimulus controlled eating for each participant. FINDINGS: Substantial variation was seen in both our measure of both food-related attentional bias (Range: 33.9 to 80.0) and in the degree to which the participant's eating could be categorised as being under stimulus control (Range: 0.50 to 0.93). However, food-related attentional bias scores were not a significant independent predictor of stimulus control and nor was this relationship moderated by impulsivity. CONCLUSION: Contrary to theoretical predictions, we found no evidence that of an association between attentional bias, impulsivity, and stimulus control. More work is needed to better understand the implicit processes underlying eating behaviour in the real-world.

Measuring Food-Related Attentional Bias.

Objective: Food-related attentional bias has been defined as the tendency to give preferential attention to food-related stimuli. Attentional bias is of interest as studies have found that increased attentional bias is associated with obesity; others, however, have not. A possible reason for mixed results may be that there is no agreed upon measure of attentional bias: studies differ in both measurement and scoring of attentional bias. Additionally, little is known about the stability of attentional bias over time. The present study aims to compare attentional bias measures generated from commonly used attentional bias tasks and scoring protocols, and to test re-test reliability. Methods: As part of a larger study, 69 participants (67% female) completed two food-related visual probe tasks at baseline: lexical (words as stimuli), and pictorial (pictures as stimuli). Reaction time bias scores (attentional bias scores) for each task were calculated in three different ways: by subtracting the reaction times for the trials where probes replaced (1) neutral stimuli from the trials where the probes replaced all food stimuli, (2) neutral stimuli from the trials where probes replaced high caloric food stimuli, and (3) neutral stimuli from low caloric food stimuli. This resulted in three separate attentional bias scores for each task. These reaction time results were then correlated. The pictorial visual probe task was administered a second time 14-days later to assess test-retest reliability. Results: Regardless of the scoring use, lexical attentional bias scores were minimal, suggesting minimal attentional bias. Pictorial task attentional bias scores were larger, suggesting greater attentional bias. The correlation between the various scores was relatively small (r = 0.13-0.20). Similarly, test-retest reliability for the pictorial task was poor regardless of how the test was scored (r = 0.20-0.41). Conclusion: These results suggest that at least some of the variation in findings across attentional bias studies could be due to differences in the way that attentional bias is measured. Future research may benefit from either combining eye-tracking measurements in addition to reaction times.

Comfort eating: An observational study of affect in the hours immediately before, and after, snacking.

OBJECTIVE: 'Comfort eating' has been used to explain real-world food choices, suggesting that individuals are drawn to energy-dense ('unhealthy') snacks when experiencing negative affect. However, this concept has rarely been studied, particularly in real-world settings. Similarly, the effects of snacking on subsequent affect are also poorly understood. The present study aimed to examine the association between affect and snacking in daily life. METHODS: One hundred and forty-one adults recorded their food intake in real time for ~14 days using a study issued mobile phone. Participants also responded to randomly timed assessments. During both types of assessments, participants indicated their current level of affect. By anchoring off snacking events, the trajectory of affect in the hours leading up to - and following - snacking was explored. RESULTS: In the three hours leading up to a healthy snack, affect was stable. In contrast, affect fell during the hours leading up to an unhealthy snack. The interaction between snack type and time was significant. A similar, but opposite, pattern was seen following snacking: where affect decreased after unhealthy snacking, affect increased following healthy snack intake. CONCLUSION: The findings are consistent with the hypothesis of comfort eating, with unhealthy snacking being preceded by worsening affect. Unhealthy snacking did not, however, lead to affect improvements afterwards, which questions the 'effectiveness' of comfort eating. The intake of healthy snacks however was associated with positive affective experiences. These findings could function as a component of interventions aiming at improving dietary behaviours.

Body Mass Index and stimulus control: Results from a real-world study of eating behaviour.

BACKGROUND: Evidence suggests decisions about when, what, and how much to eat can be influenced by external (location, food outlet presence, food availability) and internal (affect) cues. Although the relationship between stimulus control and obesity is debated, it is suggested that individuals with higher BMIs are more driven by cues to eating than individuals in the healthy-weight range (HWR). This study investigates the influence of stimulus control on real-world food intake, and whether stimulus control differs by BMI. It was hypothesised that, compared to those in the HWR, eating among individuals with higher BMIs would be under greater stimulus control. METHOD: 74 participants (n = 34 BMI < 24.9, n = 40 BMI > 24.9) recorded food intake for 14 days using Ecological Momentary Assessment. Participants also responded to 4-5 randomly-timed assessments per day. Known external and internal eating cues were assessed during both assessment types. Within-person logistic regression analyses were used to predict eating vs. non-eating occasions from stimulus control domains. FINDINGS: Results support the hypothesis that eating was influenced by stimulus control: food availability, affect, time of day, and location significantly distinguished between eating and non-eating instances (AUC-ROC = 0.56-0.69, all p's < 0.001). The presence of food outlets was significantly better at distinguishing between eating and non-eating instances for those with higher BMIs (compared to individuals in the HWR). DISCUSSION: Results support the notion of stimulus control in shaping eating decisions. Differences in levels of stimulus control between participants in the HWR compared to those with a high BMI suggest that dietary improvement interventions may be more effective when they are tailored to the individual and consider environmental influences on eating behaviour.