Nutrition Facts labels have been used for decades on many food products. Are these labels read in detail by consumers when making purchases? Do people read only certain portions of the labels? According to a new study published in the November issue of the Journal of the American Dietetic Association, consumers' self-reported viewing of Nutrition Facts label components was higher than objectively measured viewing using an eye-tracking device. Researchers also determined that centrally located Nutrition Facts labels are viewed more frequently and for longer than those located peripherally（周边地） . "The results of this study suggest that consumers have a finite attention span for Nutrition Facts labels: although most consumers did view labels, very few consumers viewed every component on any label," according to investigators Dan J. Graham, PhD, and Robert W. Jeffrey, PhD, Division of Epidemiology and Community Health, University of Minnesota, Twin Cities. "These results differed from the self-reported survey responses describing typical grocery shopping and health behaviors submitted by the participants."

Currently most US Nutrition Facts labels are positioned peripherally, not centrally, on food packages and, as such, may be less likely than they could be to catch and hold the eye of a potential consumer, according to the study.

In a simulated grocery shopping exercise, 203 participants observed 64 different grocery products displayed on a computer monitor. Each screen contained three elements, the well-known Nutrition Facts label, a picture and list of ingredients（材料，作料） , and a description of the product with price and quantity information. These three elements were presented so that one third of the participants each saw the Nutrition Facts label on the left, right, and center. Each subject was asked whether they would consider buying the product. Participants were aware that their eye movements would be tracked, but unaware that the study focus was nutrition information.

Using a computer equipped with an eye-tracking device, investigators observed that most consumers view label components at the top more than those at the bottom. Further data suggest that the average consumer reads only the top five lines on a Nutrition Facts label.

Self-reported viewing of Nutrition Facts label components was higher than objectively measured viewing. 33% of participants self-reported that they almost always look at calorie content on Nutrition Facts labels, 31% reported that they almost always look at the total fat content, 20% said the same for trans-fat content, 24% for sugar content, and 26% for serving size. However, only 9% of participants actually looked at calorie count for almost all of the products in this study, and about 1% of participants looked at each of these other components (total fat, trans fat, sugar, and serving size) on almost all labels.

When the Nutrition Facts label was presented in the center column, subjects read one or more sections of 61% of the labels compared with 37% and 34% of labels among participants randomly assigned to view labels on the left- and right hand sides of the screen, respectively. In addition, labels in the center column received more than 30% more view time than the same labels when located in a side column.

"Taken together, these results indicate that self-reported Nutrition Facts label use does not accurately represent in vivo use of labels and their components while engaging in a simulated shopping exercise. In addition, location of labels and of specific label components relate to viewing. Consumers are more likely to view centrally located labels and nutrients nearer the label's top. Because knowing the amounts of key nutrients that foods contain can influence consumers to make healthier purchases, prominently positioning key nutrients, and labels themselves, could substantially impact public health."