Salivary responding and the duration of measurement

Eliciting real cravings with virtual food: Using immersive technologies to explore the effects of food stimuli in virtual reality

In this paper, we explore the current technical possibilities of eating in virtual reality (VR) and show how this could be used to influence eating behaviors. Cue-based exposure therapy is a well-known method used to treat eating disorders. There are several benefits to using VR in combination with cue-based therapy. However, before VR-based cue-exposure can be used for therapeutic purposes, the ability of the VR environment to elicit craving responses in participants must be assessed. This was the objective of the first part of the study, where we assessed whether our VR environment elicited food craving responses in participants. Results showed that our VR environment elicited food craving responses: Salivation Magnitude, Food Craving State and Urge to Eat was significantly different from the neutral baseline. In addition, results showed that food cravings measured through the salivation magnitude in response to the virtual condition were not significantly different from the real condition, thus showing that VR had a comparable effect on producing food cravings. The second part of the study was conducted to determine whether the addition of olfactory and interaction cues in VR increased the development of food cravings. The results of this part showed that adding synthetic olfactory cues, paired with visual cues, to our system, provided a significant further increase in food cravings. Our results demonstrate that the use of food cues in VR can increase the development of food cravings and that it is possible to provide a simple yet convincing eating experience in VR. Inevitably, food interaction in VR is still underexplored territory and further research is needed to improve utility and application in disciplines related to food and eating.

Semantic conditioning of salivary pH for communication

OBJECTIVES

Semantic conditioning of salivary pH was investigated as a new paradigm for binary communication.

METHODS AND MATERIALS

In a sample of eleven healthy participants, affirmation or negation of presented statements were paired with milk and lemon to condition changes in salivary pH level.

RESULTS

Significant differences between the conditioned reactions were found at the group level. However, the analysis of pH changes on single-subject level revealed significant differences between affirmative and negative responses to the presented statements only for isolated samples in few participants. When classifying a change in pH value of more than .01 as correct response to a statement, only responses to affirmative statements reached mean accuracies of more than 60%.

CONCLUSION

Improvements in the paradigm are necessary before testing it with the critical target population of patients to prove its profit for basic yes/no communication in case no other reliable means of communication could be preserved.

Recording of swallowing events using electromyography as a non-invasive measurement of salivation

The present study examined whether the measurement of swallowing activity by electromyography (EMG) provides a sensitive and valid method for the assessment of the amount of saliva secreted. Thirteen subjects tasted lemon juice and water, and smelled lasagna and hay, while the amount of saliva, measured with the aid of cotton dental rolls, was compared with the number of peaks in the EMG activity of the musculus digastricus. Swallowing indeed differentiated between the stimuli and the correlation between the number of swallows and the amount of saliva was significant. The present data suggest that monitoring the swallowing movement using EMG might be a sensitive, valid and reliable method for the measurement of salivary flow. The use is recommended for the measurement of salivation when a simple and non-invasive method is needed.

Allocation of attentional resources during habituation to food cues

Two experiments were designed to test the hypothesis that habituation to repeated food cues can be inhibited by allocating processing resources to nonfood cues. In two experiments, the salivary response to 10 presentations of lemon yogurt was assessed while subjects engaged in a controlled cognitive search task (demanding attentional resources), an automatic search task (needing fewer attentional resources), or no task. In Experiment 1, the controlled and automatic search tasks differed in the number of memory set items. In Experiment 2, the size of the memory sets was held constant, and individuals were provided practice to stabilize the different search strategies in the task. The automatic search and no task groups habituated to the repeated presentation of food cues in both experiments, but the controlled search group did not. These results support the hypothesis that allocation of attentional resources to external cues can influence the processing of food cues.

Differences in salivation to repeated food cues in obese and nonobese women

In a series of studies we have shown that salivation, a cephalic phase preingestive response, habituates to repeated presentations of olfactory or gustatory cues in nonobese subjects. Previous research has studied the differences in anticipatory response to food cues in obese vs. nonobese subjects. This study was designed to assess if obese and nonobese females differed in their patterns of salivary response to repeated presentation of palatable food cues. The salivary response to 10 gustatory presentations of lemon yogurt was studied in 10 obese and 10 nonobese nonrestrained women. Results showed significant differences in the pattern of salivary responding, with obese subjects showing a significantly slower decline in salivation than nonobese subjects. These results are consistent with the hypothesis that obese women differ from nonobese women in their pattern of response to repeated food cues. The results are discussed in relationship to models of intake that focus on differences in satiety or differences in the reinforcing value of food between obese and nonobese subjects.