Food Image Study: Ambivalent motivation, attentional bias to threat, and thought shape fusion in restrained eaters
Description
Background: Individuals who engage in restrained eating are often torn in a standoff between craving and dieting goals. This approach-avoidance conflict has been hypothesized to play a central role in the development of eating pathology. An emerging body of evidence suggests that one’s motivation to approach vs. avoid threat may modulate their attentional biases to threat. However, little is known about the link between ambivalent motivation towards food, visual attention to food, and eating pathology in restrained eaters. Methods: We had restrained eaters complete a passive viewing task where their eye movements towards high calorie food images vs. neural objects were tracked. Participants also rated their motivation to look towards vs. away from food images. Results: Participants who were ambivalent about whether to look towards or away from food images demonstrated a unique pattern of visual attention to food and reported greater thought-shape fusion and more restrained eating behaviours than other groups. Conclusions: Our findings suggest that some restrained eaters indeed experience ambivalent motivation towards high calorie food, which in turn modulates their attentional biases to food and contributes to cognitive distortions that are unique to eating pathology. Based on Cisler and Koster (2010), Nelson et al. (2015), and Xu et al. (2021), we hypothesized that: (1) some restrained eaters would exhibit high motivation to both look towards and look away food images (that is, would be ambivalent); (2) motivation to look towards and look away from food images would influence visual attention such that the ambivalent group would show initial facilitated attention to food, followed by no maintenance of initial attention to food, and they would also look at food less than the engagers and more than the avoiders; and (3) relative to other groups, those who were ambivalent about whether to look towards or away from food images would exhibit greater thought-shape fusion and more negative affect at the end of the study. Our results suggest that restrained eaters may vary in their motivation to approach vs. avoid images of high calorie food, and subsequently demonstrate different patterns of attentional biases to food. Individuals who were ambivalent about whether to look towards or away from food images reported more restrained eating behaviours and greater thought shape fusion. This study provides evidence to the critical role that approach-avoidance conflict may play in the development and maintenance of eating pathology (Stroebe, 2008; Werthmann et al., 2015). Ambivalent motivation to food may also be an important factor to address in treatment.
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Self-report measures: 1. Restraint Scale-Concern for Dieting sub-scale 2. Positive and Negative Affect Schedule 3. Trait Thought Shape Fusion Scale: Short Version 4. At the end of this study, participants were asked to answer the following question “how long has it been since you last ate”, rounded to the nearest half hour. Participants also reported their current height and weight, based on which their Body Mass Index (BMI) was calculated. The Eye Movement Attention Task (EMAT; Nelson et al., 2015) is an eye-tracking task that measures attentional bias to images. Participants were told that image pairs would be presented on the computer screen, and they were to look at these images freely. In each trial, participants had to fixate on a centrally located cross first, after which a high calorie food image was presented simultaneously with a neutral image. The image pair was displayed for five seconds, followed by a 500ms interval before the appearance of the next fixation cross. For each participant, there were two practice trials and 60 testing trials in total. Each image (512 × 384 pixels) was displayed such that its closest edge was 80 pixels from the centre of the screen (2.7° visual angle for horizontal positioning and 2.5° visual angle for vertical positioning), on a light grey background. We used the SR Research Ltd. EyeLink 1000TM (Mississauga, Ontario, Canada) desktop-mounted eye-tracking system to record participants’ eye movements during the EMAT. Participants were positioned in a chin and forehead rest and situated approximately 65 cm from a 19-inch LCD colour monitor (resolution: 1280 × 1024). Recorded eye movement data was coded using the EyeLink Data Viewer software (SR Research Ltd., 2015). The standard settings identifying saccades and fixations were used, i.e. a saccade was considered an eye movement that travels at least 30° per second or with an acceleration of at least 8000° per second. Eye movements that did not meet these criteria were classified as fixations. Immediately after the EMAT, participants were presented with a selection of the images they had viewed in the EMAT. For each image, on a 9-point Likert Scale (from 1 “No motivation at all” to 9 “Very strong motivation”), participants provided two separate reports of motivation: (1) “how motivated were you to look towards this image?”, and (2) “how motivated were you to look away from this image?”. A total number of 30 images (15 food images and 15 neutral images) were randomly presented to each participant. We manually defined the food and neutral images as two areas of interests (AOIs). For each AOI, we generated the following three indices of eye movements: (1) time to first fixation (TTFF); (2) first fixation gaze duration (FFGD); and (3) proportion of viewing time (PVT). We also divided each 5000ms testing trial into ten 500ms intervals and calculated the PVT for food and neutral images within each time interval.