Cream and a Little Sugar

I'm a one cup a day coffee drinker but boy does it make a difference, or so I think.

From Neuroskeptic...

Are the benefits of coffee really due to the caffeine, or are there placebo effects at work? Numerous experiments have tried to answer this question, but a paper published today goes into more detail than most.

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.

Finally, no-one who got the decaf noticed that it didn't actually contain caffeine, and the volunteer's ratings of their alertness and mood didn't differ between the caffeine and placebo groups. So, this suggests that if you were to secretly replace someone's favorite blend with decaf, they wouldn't notice - although their performance would nevertheless decline.