Sensory-specific Appetition: Postingestive Detection of Glucose Rapidly Promotes Continued Consumption of a Recently Encountered Flavor

It is generally thought that macronutrients stimulate intake when sensed in the mouth (e.g., sweet taste) but as food enters the GI tract its effects become inhibitory, triggering satiation processes leading to meal termination. Here we report experiments extending recent work (see [1]) showing that under some circumstances nutrients sensed in the gut produce a positive feedback effect, immediately promoting continued intake. In one experiment, rats with intragastric (IG) catheters were accustomed to consuming novel flavors in saccharin daily while receiving water infused IG (5 ml/15 min). The very first time glucose (16% w/w) was infused IG instead of water, intake accelerated within 6 mins of infusion onset and total intake increased 29% over baseline. Experiment 2 replicated this stimulatory effect with glucose infusion but not fructose nor maltodextrin. Experiment 3 showed the immediate intake stimulation is specific to the flavor accompanying the glucose infusion. Rats were accustomed to flavored saccharin being removed and replaced with the same or a different flavor. When glucose infusion accompanied the first bottle, intake from the second bottle was stimulated only when it contained the same flavor, not when the flavor switched. Thus we confirm not only that glucose sensed postingestively can have a rapid, positive feedback effect ('appetition' as opposed to 'satiation') but that it is sensory-specific, promoting continued intake of a recently encountered flavor. This sensory specific motivation may represent an additional psychobiological influence on meal size, and further, has implications for the mechanisms of learned flavor-nutrient associations.

Psychological Flow In A Physical Task

Psychological flow describes the mental phenomenon that takes place during intense engagement with a task (Jackson & Csikszentmihalyi, 1999). Its components have been operationalized through the development of the Flow State Scale (Jackson & Eklund, 2002). As feedback has been shown to be a critical element for the facilitation of a flow experience (Moneta, 2012), the current study sought to investigate the effect of differential feedback on psychological flow outcomes using the FSS as the dependent variable. The feedback manipulation featured three experimental groups; control, positive, and negative. This study also accounted for the personality trait of perfectionism as a variable influencing the experience of flow. Following the completion of a personality measure, participants engaged in a bolt threading task for ten minutes, then reported the time they perceived to have spent on the task as well as the outcome of their flow experience. The feedback conditions were created by the use of different size containers for participants to place their nut and bolt pairs in, and thus feedback was inherent in the task. The study found that feedback played an important role in the outcome of a flow experience. The positive feedback condition was more conducive to flow than the negative feedback condition. Furthermore, those in the positive condition outperformed those in the negative condition during the ten minutes. Goal clarity and feedback clarity differed significantly across feedback manipulations. Perfectionism¿s impact on the outcome of flow was more pronounced in the negative feedback condition than the positive or control conditions. In settings where engagement and performance are imperative, ample attention should be given to the feedback processes present in the situation.