Brian Wansink, director of the Cornell University's Food and Brand Lab, had two groups of college students -- 98 students total -- eat tubes of potato chips, some of which contained chips dyed red, while they were watching video clips in class.
The study, scheduled to be published in the journal Health Psychology, found the red chips served as subconscious "stop signs" that curtailed the amount of food consumed.
In the first study, the red chips were interspersed at intervals designating one suggested serving size, or seven chips, or two serving sizes, or 14 chips. In the second study, this was changed to five and 10 chips.
Unaware of why some of the chips were red, the students who were served the segmented tubes ate 50 percent less than their peers.
"People generally eat what is put in front of them if it is palatable," Wansink said in a statement. "An increasing amount of research suggests that some people use visual indications such as a clean plate or bottom of a bowl to tell them when to stop eating."