Neuroskeptic reports on some interesting results from a coffee study:
The authors took 60 coffee-loving volunteers and gave them either placebo decaffeinated coffee, or coffee containing 280 mg caffeine. That’s quite a lot, roughly equivalent to three normal cups. 30 minutes later, they attempted a difficult button-pressing task requiring concentration and sustained effort, plus a task involving mashing buttons as fast as possible for a minute.
The catch was that the experimenters lied to the volunteers. Everyone was told that they were getting real coffee. Half of them were told that the coffee would enhance their performance on the tasks, while the other half were told it would impair it. If the placebo effect was at work, these misleading instructions should have affected how the volunteers felt and acted.
Several interesting things happened. First, the caffeine enhanced performance on the cognitive tasks — it wasn’t just a placebo effect. Bear in mind, though, that these people were all regular coffee drinkers who hadn’t drunk any caffeine that day. The benefit could have been a reversal of caffeine withdrawl symptoms.
H/T to Tyler Cowen for the link.
