Abstract
Reaction time indices of attentional biases toward food and food-related stimuli have been shown to vary with changes in motivational state (i.e., hunger) and variations in body mass index (BMI). The current study used eye-tracking methodology to examine how attentional biases towards different food images are moderated by hunger and BMI. Twenty-six women (15 normal BMI, 11 overweight or obese; 13 sated, 13 hungry) viewed pairs of images of high-calorie sweet, high-calorie salty, and low-calorie foods while eye movements were monitored. Proportions of initial fixations to the different food types were used as an index of attentional capture and pupil diameter as an index of emotional arousal. Results revealed a significant interaction between food type and BMI: the overweight group had a greater proportion of first fixations on low-calorie food images relative to the normal weight group (who had a tendency to fixate first on high-calorie salty images). These results are consistent with reaction time data showing more positive implicit attitudes to high-calorie salty foods (e.g., pizza, burger; Czyzewska & Graham, 2007). In addition, there was a significant food type by hunger interaction: the hungry group made more initial fixations to high-calorie salty foods (relative to low-calorie foods), suggesting that hunger temporarily enhances attentional capture by high-calorie salty foods. Furthermore, the effects of BMI and hunger on attentional capture to these foods are statistically separable. In contrast, pupil diameters did not change as a result of hunger: mean pupil diameter was larger overall for the overweight group, but this main effect was mitigated by an interaction between BMI and food type wherein pupil diameters were largest to high-calorie salty foods. Overall, these results suggest that hunger and BMI have separate effects on attentional capture to food images that increase the salience of high-calorie salty foods.