Dr. Crowe's team tested 92 people with varying levels of
caffeine. The test was presented to the subjects as a hearing test; they were
told that they would be listening to a three-minute clip of white noise, in
which there might or might not be snippets of Bing Crosby singing "White
Christmas." Test subjects were instructed to press a buzzer when they
heard a piece of the song but the clip actually had no music in it at all. A few
individuals among the non-caffeinated group heard Crosby's voice; but the
coffee drinkers were three times as likely to press the buzzer.
The effect was even more evident with people who described themselves as "stressed" and who drank coffee. The study was not well controlled as the caffeine intake was self-reported and naming the song participants would expect to hear would have had a hand in shaping their expectations. It is also possible that the subjects would have experienced cognitive disequilibrium when forced to choose between intolerable minutes of white noise or equally intolerable snippets of "White Christmas."
Another recent survey found
that people who drank three or more cups of coffee per day were three times
more likely than other people to report hearing and seeing things that aren't
there, although there would be additional factors to consider, such as medical history
and mental stability... was that the phone?
Other studies show that coffee, like anything, is probably okay for most of us if consumed in reasonable amounts. Auditory hallucinations like a ringing phone or catching those shadow people from your peripheral are but minor side effects, as caffeine has been known to increase endurance, reduce the risk of heart disease and kidney stones, and increase short-term memory and ability to focus. It also increases the likelihood that I'll be a bearable person to be around.
On a recent camping trip with a group of friends, we woke up to the realization that the only jar of coffee included in the supplies was decaf. Fingers were pointed, words were said, and what started as a weekend of fun-filled adventure quickly turned into the George Washington National Forest version of Lord of the Flies.