16.21 The influence of subliminal messages.

Can “subliminal” messages that are below our threshold of awareness nonetheless influence us? Advertisers, among others, want to know. One study asked if subliminal messages help students learn math. A group of students who had failed the mathematics part of the City University of New York Skills Assessment Test agreed to participate in a study to find out. All received a daily subliminal message, flashed on a screen too rapidly to be consciously read. The treatment group of 10 students was exposed to “Each day I am getting better in math.” The control group of eight students was exposed to a neutral message, “People are walking on the street.” All students participated in a summer program designed to raise their math skills, and all took the assessment test again at the end of the program. Here are data on the subjects’ scores before and after the program.⁹