Elsevier

Appetite

Volume 50, Issue 1, January 2008, Pages 139-145
Appetite

Research Report
Decreasing dislike for sour and bitter in children and adults

https://doi.org/10.1016/j.appet.2007.06.008Get rights and content

Abstract

Strategies for preference conditioning were investigated in children (Experiment 1) and adults (Experiment 2). In Experiment 1, subjects were 49 children, between the ages of 2 and 5 years old. The results showed that initially mixing grapefruit juice with the sweet taste of sucrose increased liking for the sour taste of grapefruit juice (without the added sucrose) and that this increased liking persisted weeks later. In Experiment 2, subjects were 62 undergraduates with a median age of 18 years. Consistent with Experiment 1, the results showed that initially mixing broccoli or cauliflower with the sweet taste of sugar increased liking for the bitter taste of these vegetables. The results are discussed in terms of decreasing dislike for fruits and vegetables.

Introduction

At birth human infants reject bitter and sour tastes while favoring sweet tastes such as sucrose (Desor, Maller, & Andrews, 1975; Kajiura, Cowart, & Beauchamp, 1992; Lipsitt & Behl, 1990). Although the initial affective reaction to the basic tastes (including sour and bitter) is genetically mediated, this response can be modified through experience (Capaldi, 1996; Capaldi & Hunter, 1994; Capaldi, Hunter, & Lyn, 1997). Conditioning with these basic tastes is one way to modify liking (Holman, 1975). For example, flavor–flavor conditioning occurs when a conditioned stimulus (CS; e.g., an odor extract) is mixed with an unconditioned stimulus (US; e.g., an innately liked taste, such as sweetness). Flavor–nutrient conditioning occurs when a CS is mixed with as caloric US (e.g., sucrose; Lyn & Capaldi, 1994). Both preference conditioning strategies increase the liking for the CS even when the US is subsequently removed, although most research in this area has focused on animals (Capaldi, Campbell, Sheffer, & Bradford, 1987; Fanselow & Birk, 1982; Holman, 1975).

Human studies have shown that undergraduates receiving several pairings of flavored tea (CS) with sucrose (US) will increase their preference for the flavor of a sweetened tea, even when it is no longer sweetened (Zellner, Rozin, Aron, & Kulish, 1983). More recent work by Stevenson and colleagues has shown that odors paired with sweet tastes are not only more liked, they are rated as smelling sweeter (Stevenson, Boakes, & Prescott, 1998; Stevenson, Prescott, & Boakes, 1995). Whether the results from these studies were mediated by flavor–flavor or flavor–nutrient learning cannot be determined since sugary solutions that contain nutrients are both flavorful and caloric.

The present studies asked whether these preference conditioning procedures will increase the pleasantness or liking for foods, such as fruit juice (Experiment 1) and vegetables (Experiment 2). In Experiment 1, we tested whether mixing sucrose with the sour taste of grapefruit juice will increase pleasantness ratings for the juice. Pairing a CS flavor with sugar effectively facilitates long-term preferences for flavors that are subsequently unsweetened in rat studies. We were interested in whether this would also facilitate long-term preferences for grapefruit juice with children.

Section snippets

Method

Subjects: Subjects were 63 children between the ages of 2 and 5 years old. Thirty-five children were recruited from Baby Gator Educational Research Center and 28 children were recruited from a KinderCare Learning Center. Both centers were located on the University of Florida campus and the majority of the children's parents were either employed by or were students of the university. Of the 63 subjects 25 were girls and 38 were boys. Each child had to have a parental consent form signed by their

Experiment 2

Experiment 2 tested whether pairings with sucrose could also be useful in decreasing dislike for bitter tasting vegetables in a sample of college students. College students were used as subjects to extend the generality of the findings in Experiment 1 from children to college students and from grapefruit juice to vegetables. A within-subjects mere exposure control group was included in the experiment.

Subjects: A sample of 32 undergraduates (14 males and 18 females) enrolled in an Introductory

General discussion

The results from Experiment 2 demonstrate that sweetening vegetables on only three occasions was sufficient to increase pleasantness ratings for these vegetables, even when they were subsequently unsweetened. Mere exposure was not sufficient to produce this change in pleasantness ratings. Also, special care was taken to ensure that hunger and fullness states were similar in each group by only including subjects who followed the instructions for eating prior to the experimental procedures.

Acknowledgment

This research was supported by the Florida Citrus Foundation.

References (18)

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