A schematic drawing of the trials using a Simon task and examples of both corresponding (C) and non-corresponding (NC) conditions (on the right) and the three types of distractors presented during the task: a food item, an object, and a neutral distractor (on the left).

The experimental setting was a dimly lit room. Each participant was seated in front of (58 cm away from) a 15-inch CRT computer screen. The task consisted of 480 experimental trials presented in four blocks, each consisting in 120 trials. A practice block of 42 trials preceded the beginning of the real session. The participant was reminded by a message appearing on the screen before he/she read the instructions for the task and at the beginning of each block of trials that that he/she would be able to eat immediately (if he/she was in Group 1) or 2 h later (if he/she was in Group 2).

Each trial started with a central black fixation cross subtending 0.5° of visual angle, displayed on a light gray background. The fixation cross was surrounded by a black square perimeter with the side subtending 3° of visual angle. After a variable interval, ranging from 2000 to 3500 ms, the target stimuli were presented at an eccentricity of 4.5° of visual angle on the left or right of the fixation cross for 147 ms. The target stimuli were 4 × 4 red-and-black or green-and-black checkerboards subtending 1.48° of visual angle. A 4 × 4 black-and-white checkerboard was presented together with the target as contralateral filler. A central distracter (a cross) was also displayed inside the square for 2000 ms. The distracters consisted of images of food, objects, or a black cross projected on a white background (neutral condition). The duration of the inter-trial intervals ranged from 1000 to 2000 ms. Ten food and 10 non-food images (objects) were selected from a validated dataset (Blechert et al., 2014)1.

The participants were instructed to keep their eyes on the screen and to respond to the task-relevant stimulus as quickly and accurately as possible. Half of the participants were instructed to press the left button (the letter “Z” of the keyboard) with their left index finger if the target was the red-and-black checkerboard, and the right button (the letter “M”) with their right index finger if it was the green-and-black one, independently of its spatial position.

These instructions were inverted for the other half of the participants. The three types of distracters (a piece of food, a non-food object, and a cross on a neutral white background which we considered a neutral condition) were presented in half of the cases with corresponding color/location responses and in the other half with non-corresponding color/location responses. The RTs and the accuracy of the responses of each participant for each trial were registered. Individual RTs and accuracy (i.e., probability of correct response) in the different task conditions were screened for outliers, given a cutting point of 2 standard deviations (SD) from the mean response value (conservative threshold). The data of one participant whose percentage of correct responses was lower than two SD of the mean accuracy rate were not included in our analyses.

To control for a speed accuracy trade-off, the mean RTs adjusted for response accuracy [adjRTs = RTs/p (correct response)] were calculated. Data are reported as means ± SD.

The Yale Food Addiction Scale (Innamorati et al., 2015) was used to investigate additive eating patterns, the Binge Eating Scale (BES; Gormally et al., 1982) was used to investigate the presence of binge eating behavior, the Power of Food Scale (PFS; Lowe et al., 2009) was used to investigate the attraction to food, the Dutch Eating Behavior questionnaire (DEBQ; van Strien et al., 1986) was used to assess emotional, external, and restrained eating patterns, and the Eating Attitude Test 26 Item (EAT-26; Garner et al., 1982) was used to investigate eating disorders. The Barratt Impulsiveness Scale (BIS-11; Fossati et al., 2001) and the Behavioral Inhibition System/Behavioral Activation System (BIS/BAS; Carver and White, 1994) were used to measure two motivational systems.

The participants’ subjective levels of hunger, satiety, and desire to eat were rated using Likert scales ranging from −5 (max) to 5 (min).

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