It's the texture of food as much as its taste that drives diet choices for many of us, a study has found, as people think of foods with rough textures or hard consistency as having fewer calories.

In a laboratory setting, researchers at the University of South Florida had study participants sample a variety of foods that were hard or soft, or rough or smooth, and then give an estimate of their calorie counts.

In another experiment, people were asked to watch and rate a number of television ads, thinking that was the point of the test, but while doing so were given "thank you" offerings of bite-sized brownies for their participation.

Some were given softer-textured brownies while the other half got brownies with a harder, crunchy texture. Participants asked to estimate their caloric content ate more of the harder brownies than the soft one, the researchers found, while those who were not asked anything about calories tended to consume more of the softer brownies.

"We studied the link between how a food feels in your mouth and the amount we eat, the types of food we choose, and how many calories we think we are consuming," Dipayan Biswas and Courtney Szocs, authors of a study submitted to the Journal of Consumer Research, say.

Researchers from Columbia University and the University of Michigan also contributed to the study.

For the most part, the researchers say, how food feels in the mouth -- defined as "oral haptics" or mouthfeel -- can affect our perception of its calorie level.

The phenomenon can also affect our choices of about the amount of certain kinds of food we end up consuming, they say.

"This 'oral haptics-calorie estimation' (OHCE) effect is driven by the lower mastication [chewing] effort and the higher orosensory perception for soft (versus hard) and smooth (versus rough) foods," the researchers reported.

Food brands that want to promote the healthy nature of their offerings might want to consider emphasizing the texture of their foodstuffs in addition to their low calorie content, the researchers suggest.

"Understanding how the texture of food can influence calorie perceptions, food choice, and consumption amount can help nudge consumers towards making healthier choices," they wrote.