Research

Animal Research :

The primary objective of the program of research is to assess how animals learn about the perceptual qualities of taste and flavor extract stimuli as well as to determine the processes underlying learning about flavor stimuli in the conditioned flavor preference preparation. This program of research is important for theories of learning, which have been primarily based on conditioned aversion learning. This work expands current conceptions of learning based on sensory preconditioning (SPC), potentiation (see Table 1 for description) and additional learning paradigms in the less understood conditioned flavor preference preparation. Such experiments can be used to understand how flavor preferences are enhanced and may potentially be used to increase liking in humans for less preferred but healthier foods.

Table 1 . A and B = flavor stimuli, + = reinforcement (e.g., a caloric solution such as sucrose). In sensory preconditioning A and B represent flavor stimuli, where flavor B is the trained stimulus, and flavor A is the sensory preconditioned stimulus presumably associated with B during the preconditioning trials. Sensory preconditioning is said to occur when conditioning is evident to A, which was never physically paired with a reinforcer. In potentiation, A and B also represent flavor stimuli and are trained together. The weaker cue (stimulus A) is tested for the strength of conditioning compared to a group receiving only A+ training. Potentiation is said to occur when AB+ trials produce stronger conditioning to A than A+ trials.

Abstracts of current research projects:

Capaldi, E. D. & Privitera, G. J. (submitted). Potentiation of odor by taste in conditioned flavor preference learning. Journal of Experimental Psychology: Animal Behavior Processes .

ABSTRACT: The efficacy of the potentiation paradigm was investigated using stimuli that have been shown to produce potentiation in aversion paradigms. Almond and banana extracts, which have strong odor components, were combined with salt and saccharin in conditioned flavor preference conditioning. The results showed that tastes potentiated preference conditioning to extracts, while extracts did not potentiate preference conditioning to tastes, similar to the asymmetry observed using an aversion paradigm. These are the first reports demonstrating potentiation in flavor preference conditioning.

Capaldi, E. D. & Privitera, G. J. (submitted). The effectiveness of sensory preconditioning is dependent on the “weak cue – strong cue” contingency in preference learning. Learning & Behavior .

ABSTRACT: This preference study investigated the sensory preconditioning paradigm (denoted AB/B+) with a variety of taste and extract combinations making the following assumption of salience: extracts > tastes > odors. Subjects were assigned to 1 of 3 conditions based on whether a taste, extract, or odor cue was used as flavor A. The patterns of results in each condition showed that sensory preconditioning was only effective when flavor A was relatively weaker than, or of similar salience to the trained flavor B. The results suggest a “weak cue – strong cue” contingency similar to that observed in the potentiation paradigm.

Privitera, G. J. & Capaldi, E. D. (in press). The basic tastants in aversion conditioning: Evidence for sensory preconditioning and not potentiation. Learning & Behavior .

ABSTRACT: Experiment 1 used a potentiation paradigm to test the relative influence of odor and taste using 2 basic tastants (i.e., salt and sweet) in conditioned aversion learning.   Experiment 1 showed that aversions to tastants (salt or sweet presented in a manner by which it could be tasted) were only established in subjects trained with the tastant, not the odor (i.e., salt or sweet presented in a manner by which it could not be tasted). Experiment 2 demonstrated using a sensory preconditioning procedure that the expression of an aversion to tastants was dependent on previous tastant experience prior to odor aversion training. These results suggest that while subjects can smell salt and sweet solutions, these odors are neither sufficient, nor necessary for the expression of a conditioned tastant aversion.  

Human Research:

The primary objective of the program of research is to assess how humans acquire and express preferences for distinctively flavored foods as well as to determine the processes underlying learning about these foods. Understanding how food preferences are acquired could lead to the development of more effective methods for producing preferences for low calorie nutritious foods, which would be important in treating obesity. Also, understanding how food preferences are learned may enable us to change food preferences towards more healthy foods and diet alternatives, which would lead to more practical strategies for maintaining long-term healthy eating patterns. Three learning paradigms are tested:

Mere Exposure : consuming a food repeatedly, without overt reinforcement, increases preference for that food.

Flavor-Flavor Learning : Pairing a food with an already liked taste of food increases preference for that food. In this learning paradigm, the already liked taste has no nutritional value (contains no calories).

Flavor-Nutrient Learning : Pairing a taste or flavor with nutrients (i.e., calories) increases liking for that food.

In studying food choice in humans, several factors have been emphasized in the literature. These factors can be generally divided into those that stress internal, metabolic processes and those that stress external processes affecting short and long-term food choices. Eating patterns likely take form as a result of the interaction between these many processes, and learning is undoubtedly fundamental to the development of the controls of food choices, ultimately regulating food intake. As such our studies aim to address multiple features of humans feeding patterns including but not limited to, meal initiation and termination, meal frequency, snacking, sensory and nutritional qualities of foods, and prolonging satiety and hunger.

Abstract of current research projects:

Capaldi, E. D., Owens, J. Q., & Privitera, G. J. (2006). Isocaloric meal and snack foods differentially affect eating behavior. Appetite , 46 (2), 117-123.

ABSTRACT: The present study tested whether foods categorized as meals reduce subsequent intake more than isocaloric foods categorized as snacks. The study was repeated three times with variations. In each variation we manipulated whether subjects received meal or snack foods in an isocaloric load. In Variation 1, subjects consumed less following a load of meal foods than snacks. Variation 2 found this effect to be short-term, affecting food choice 20 minutes following a load but not 3 hours later. Variation 3 demonstrated: (1) this effect occurs independent of the effects of the weights of foods, and (2) this effect varies specifically with subject perceptions of foods (i.e., whether they are part of a meal or snack). These results are discussed in terms of how cognitive representations of preload foods can influence subsequent consumption.