The Interaction of Food-Quantity Differences and Temporal Presentation on the Amount of Food People Consume

The Interaction of Food-Quantity Differences and Temporal Presentation on the Amount of Food People Consume Jessica M. Choplin (jchoplin@depaul.edu) and Laura Motyka DePaul University Department of Psychology 2219 North Kenmore Avenue Chicago, IL 60614-3504 they ate. Previously published empirical results (Brigell & Uhlarik, 1979; Jordan & Uhlarik, 1984; Massaro & Anderson, 1971; Schiano, 1986) and proposed theories of attribute evaluation (Anderson, 1965, 1981; Choplin & Hummel, 2002; Parducci, 1965; Wedell, Parducci, & Geiselman, 1987) predict very different patterns of how these two factors are likely to interact to bias food-quantity judgments and the amounts of food people eat. The research presented here thereby represents a preliminary opportunity to pit these seemingly contradictory empirical results and theories of attribute evaluation against each other to see which might best fit food-quantity judgments and the amounts of food people eat. Abstract Previous research suggests that judgments of food quantity affect the amounts of food people eat. In two experiments, we investigated the interaction of food-quantity differences and temporal presentation on participants’ judgments of food quantity and the amounts they ate. In Experiment 1, participants viewed drawings of two portions of mashed potatoes presented either simultaneously or sequentially and later recalled sizes from memory. In Experiment 2, participants viewed two serving bowls of pasta salad presented either simultaneously or sequentially and ate as much or as little as they wished from the smaller bowl. The amounts they ate were inversely related to biases in judgments of food quantity. Keywords: Dietary decision making; size judgments; attribute evaluation. Range-Frequency and Integration Theories Wedell, Parducci, and Geiselman (1987) presented pictures of women’s faces either simultaneously or sequentially and asked their participants to rate the physical attractiveness of the faces. They found assimilation effects (evaluations of the attractiveness of target faces were biased toward the attractiveness of contextual faces) when faces were presented simultaneously and contrast effects (evaluations of the attractiveness of target faces were biased away from the attractiveness of contextual faces) when faces were presented sequentially. A similar pattern has been observed in the parallel line-length illusion (Jordan & Uhlarik, 1984). Wedell et al. modeled ratings of simultaneously presented faces using Anderson’s (1965; 1981) integration theory and ratings of sequentially presented faces using Parducci’s (1965) range-frequency theory. These models predict that biases ought to be greater the larger the differences between values: the larger the difference in attractiveness between simultaneously presented values the greater the assimilation effects ought to be and the larger the difference in attractiveness between sequentially presented values the greater the contrast effects ought to be. Although attractiveness judgments might seem qualitatively different from food-quantity judgments, Wedell et al. (1987) intended their model as a general model of attribute evaluation. If food-quantity judgments follow the same pattern as attractiveness judgments, then when a small target quantity is presented at the same time as a larger quantity the small target quantity would appear larger the larger the difference between it and the larger quantity. By contrast, when a small target quantity is sequentially presented after a larger quantity the target quantity would appear smaller the larger the difference. Experiment 1 tested these hypotheses. If the amount of food people eat is inversely related to biases in judgments of food quantity, then people ought to eat more the greater the difference Food Quantity Judgments Judgments of food quantity affect the amounts of food people eat (Wansink, 2004). Specifically, in previous research the amounts participants ate were inversely related to biases in their judgments of food quantity. When participants believed that a quantity was smaller, they ate more; and when they believed that it was larger, they ate less. For example, participants ate more when food was packaged in larger containers (Wansink, 1996), served in larger portions (Edelman, Engell, Bronstein, & Hirsch, 1986; Nisbett, 1968; Rolls, Morris, & Roe, 2002), or on larger plates or bowls (Wansink & Cheney, 2005). Wansink (2004) argued that people eat more in these conditions because these factors cause people to judge quantities smaller than they actually are which, in turn, makes people believe that they ought to eat more or leaves them at liberty to eat more. Several researchers (Raghubir & Krishna, 1999; Wansink & Van Ittersum, 2003) have found that participants consume more from short-wide containers than from tall-thin containers. These researchers argued that their results could be explained because short-wide containers appear smaller than do tall-thin containers. Wansink, Painter, and North (2005) devised a particularly cleaver demonstration of the principle that people eat more when they are misled to believe that quantities are smaller than they actually are by giving their participants bowls of tomato soup that, unbeknownst to the participants, were refilled through a concealed tube as they were trying to eat the soup. These participants consumed 73% more soup on average than did control participants whose soup bowl was not refilled. The research presented here investigated the interaction of food-quantity differences and temporal presentation on participants’ judgments of food quantity and the amounts