Introduction
ABM, 5/100Same
REGRESSION, SESSION, DISEASES
The overvaluation of high-energy density palatable food cues represents a key contributor to unhealthy eating and fosters the development and maintenance of many prevalent diseasesRestoring healthy neurocognitive responses to food cues would thus constitute a potent lever to reduce excessive weight and related diseases. Recent literature suggests that this aim could be achieved via an ‘action-to-valuation’ mechanism of action; indeed, the repeated execution and inhibition of motor responses to food items modulate their perceived value and consumption (for systematic reviews, see Refs.In the present study, we tested the efficacy of an intervention involving this mechanism of action with a double-blind, placebo-controlled, non-crossover, randomized intervention trial in which we assessed whether a recommended one-month parallel practice of Go/NoGo (GNG) and an attentional bias modification (ABM) task decreased soda items’ valuation (as indexed by their palatability) and real-world consumption.In the GNG, we instructed the participants to respond as quickly as possible to a set of stimuli (the Go stimuli) while withholding their responses to another set of stimuli (the NoGo). With practice, NoGo stimuli end up automatically triggering motor inhibition processes. In turn, automatic approach responses and/or elevated motor excitability toward reward-associated stimuli may be reducedFor the ABM task, the participants have to respond as fast as possible to items when a Go-cue is displayed and before it disappearsBased on this literature, we posit that the associative learning of inhibition to NoGo soda cues, and the development of attentional bias away from soda cues, would synergistically reduce their value and consumption. An opposite effect might manifest for the other category of non-soda cues (low-sugar water or flavored water), which would promote the replacement of soda by healthy beverages and not merely reduce soda consumption, thereby ensuring the maintenance of hydrationWe focused on high sugar-density drinks (i.e., soda, iced tea, energy drinks) because as a source of sugar, these beverages represent a major contributor to people being overweightOur design extends and improves previous attempts at testing the efficacy of value mechanisms at several levels. First, most prior research has only involved a short, single laboratory training session, unlikely to reveal the full efficacy of this type of intervention on eating behaviorImportantly, we managed to solve the pervasive problem of expectations in cognitive interventions by using a so-called ‘mechanistic’ control groupHence, since both groups practiced the same task, they both expected to improve in the same cognitive processes. We do not expect the participants to detect the difference in the stimulus–response contingencies, as each participant only practiced one version of each task. Regardless of how a participant would interpret the stimulus–response contingency, this should not confound the outcome, because we explicitly informed both groups that we expected the intervention to reduce the perceived value of the unhealthy drink cues, and reversely for the healthy drink cues. In this way, even if more participants in the experimental group (versus the control group) detect the contingencies and form related expectations, the expectations in the control group were also set high and in the same direction.We first posited a larger decrease in unhealthy items’ palatability ratings (compared to the healthy items) in the experimental group than in the control group between the pre- and post-intervention periods (Hypothesis 1; H1). We tested this hypothesis with the triple interaction term of the between-subjects factor Intervention (Experimental; Control), and the within-subject factors Session (Pre-intervention; Post- intervention), and Drink Type (Heathy; Unhealthy). Two Intervention by Session interaction planned contrasts further tested for a larger decrease in unhealthy drink palatability (H1a) and an increase in healthy drink palatability (H1b).Next, we posited that the participants’ reported drinking consumption would show a larger reduction in the experimental group than in the control group after the intervention (Hypothesis 2; H2). We tested this hypothesis with the interaction of the factor Intervention (Experimental; Control) and Session (Pre-intervention; Post-intervention). We chose a pre- vs. post-intervention design for H2 instead of a regression model as this design allows us to detect any effect independently of which shape the curve takes during training.Finally, we expected the change in unhealthy item ratings to mediate the change in consumption (Hypothesis 3; H3). See Table Design table.102 participants (based on Monte Carlo simulations; see the ‘Minimum effect size of interest is of 5/100212 participants (based on Monte Carlo simulations independent of H1; see the ‘Minimum effect size of interest is of 5/100Same IF–THEN rule as H1Two-sided mixed ANOVA with the between-subjects factor Intervention (experimental; control) and the within-subjects factor Session (pre-intervention; post- intervention)Same equivalence rule as H1If p < 0.05 for the interaction term, then the intervention has a different effect on the experimental (versus the control group) regarding the change in unhealthy items’ palatability ratings212 participants (based on the same Monte Carlo simulations as H1a; see the ‘Minimum effect size of interest is of 5/100Same IF–THEN rule as H1Two-sided mixed ANOVA with the between-subjects factor Intervention (experimental; control) and the within-subjects factor Session (pre-intervention; post- intervention)Same equivalence rule as H1If p < 0.05 for the interaction term, then the intervention has a different effect on the experimental (versus the control group) regarding the change in healthy items’ palatability ratings210 participants (analytical power analysis; Cohen’s method; see the ‘Minimum effect size of interest is a partial Cohen’s f of 0.25Same IF–THEN rule as H1Two-sided mixed ANOVA with the between-subjects factor intervention (experimental; control) and the within-subjects factor session (pre-intervention; post- intervention)Same equivalence rule as H1If p < 0.05 for the interaction term, then the intervention has a different effect on the experimental (versus the control group) regarding the change in high sugary drink consumption104 participants (analytical power analysis; Vittinghoff, Sen and McCulloch’s method; see the ‘Both H1a and H2 must reach their minimum effect size of interest*The sample sizes mentioned for each hypothesis are the minimum sample size needed to reach a sufficient power for their respective analysis, and may be smaller or equal to the final sample size. The sample size in Table 1 were mistakenly not updated in the Stage 1 manuscript after the planned power was changed from 90 to 95%.