Physiological responses of obese subjects to external stimuli

Virtual Reality as a Tool to Study the Influence of the Eating Environment on Eating Behavior: A Feasibility Study

In this manuscript, we describe a new approach to study the effect of the eating environment on food intake and eating behavior using virtual reality technology. Fifteen adults consumed pizza rolls in two virtual reality (VR) environments: a restaurant and a table in an empty room. The participants' food intake, eating parameters (e.g., masticatory parameters and eating rate), and their sensory evaluation of the test food was measured. The participants' sense of presence (the feeling of being in the virtual environment) and markers of arousal were also measured. There was no statistical significant difference in food intake or the sensory evaluation of the test food. In the restaurant condition, participants used fewer masticatory cycles before swallowing but there was no effect on eating rate or maximum bite force. Participants experienced a greater sense of presence when they were in the pizza restaurant scene. Moreover, their heart rate and skin temperature were higher in the restaurant condition. This study suggests that VR could be developed as a new tool to study the effect of the eating environment on food intake and eating behavior.

Psychophysiological effects of audiovisual stimuli during cycle exercise

Immersive environments induced by audiovisual stimuli are hypothesised to facilitate the control of movements and ameliorate fatigue-related symptoms during exercise. The objective of the present study was to investigate the effects of pleasant and unpleasant audiovisual stimuli on perceptual and psychophysiological responses during moderate-intensity exercises performed on an electromagnetically braked cycle ergometer. Twenty young adults were administered three experimental conditions in a randomised and counterbalanced order: unpleasant stimulus (US; e.g. images depicting laboured breathing); pleasant stimulus (PS; e.g. images depicting pleasant emotions); and neutral stimulus (NS; e.g. neutral facial expressions). The exercise had 10 min of duration (2 min of warm-up + 6 min of exercise + 2 min of warm-down). During all conditions, the rate of perceived exertion and heart rate variability were monitored to further understanding of the moderating influence of audiovisual stimuli on perceptual and psychophysiological responses, respectively. The results of the present study indicate that PS ameliorated fatigue-related symptoms and reduced the physiological stress imposed by the exercise bout. Conversely, US increased the global activity of the autonomic nervous system and increased exertional responses to a greater degree when compared to PS. Accordingly, audiovisual stimuli appear to induce a psychophysiological response in which individuals visualise themselves within the story presented in the video. In such instances, individuals appear to copy the behaviour observed in the videos as if the situation was real. This mirroring mechanism has the potential to up-/down-regulate the cardiac work as if in fact the exercise intensities were different in each condition.

Influence of physiological and subjective arousal on food intake in humans

OBJECTIVES

This study explored the influence of physiologic and subjective arousal on ambient factors of the food environment, such as the eating location, the presence of other people, sound, and time of day and on food intake. It was hypothesized that the influence of environmental stimuli on food intake would be mediated by arousal.

METHODS

College students were asked to wear heart rate monitors and to record their food intake in a 7-d diet diary. Subjective arousal (elation and excitement) and aspects of the eating environment were recorded for each meal occasion.

RESULTS

Results showed that subjective arousal seems to be related to food intake (P < 0.01) and appears to be affected by environmental stimuli such as the eating location (P < 0.01) and the number of people present (P < 0.01), but only small effects of some environmental stimuli on heart rate were found with higher average heart rates in restaurants (P < 0.05). No effects of heart rate on food intake were detected. Regression analyses failed to show arousal as a significant mediator between environmental stimuli and food intake.

CONCLUSION

It can be concluded that, for normal individuals in their everyday environment, ambient influences on food intake are not mediated by changes in arousal. However, the environment and the emotional state of the individual appear to play a role in the individual's eating behavior.

Physiological arousal of obese persons to food stimuli

Physiological arousal was measured in 20 obese and 20 normal-weight subjects during presentation of imagery tasks with food- and nonfood-related stimuli and during presentation and eating of food. No differential arousal, as measured by skin conductance, was obtained between the groups for any of the stimuli. Presentation and eating of the food did produce significant arousal in subjects.