R.K. Srivastava and colleagues at the University of Bombay say a survey found people preferred red and pink tablets over other colors. Three quarters of the 600 people questioned said the color and shape of their tablets act as a memory tag for compliance.
Twice as many middle-aged people as younger adults preferred red tablets and more women than men chose red tablets, the researchers say.
The study, published in the International Journal of Biotechnology, found 14 percent of people think pink tablets taste sweeter than red tablets, while a yellow tablet is perceived as salty no matter what its actual ingredients are. In addition, 11 percent say white or blue tablets taste bitter and 10 percent say orange-colored tablets are sour.
"Patients undergo a sensory experience every time they self-administer a drug, whether it's swallowing a tablet or capsule, chewing a tablet, swallowing a liquid, or applying a cream or ointment," the researchers say in a statement. "The ritual involving perceptions can powerfully affect a patient's view of treatment effectiveness."