Psychologist George Spilich at Washington College in Chestertown, Maryland, decided to find out whether, as many smokers say, smoking helps them to think and concentrate. He put non-smokers, active smokers and smokers deprived of cigarettes through a series of tests. In the first test, each subject sat before a computer screen and pressed a key as soon as he or she recognized a target letter. In this simple test, smokers, deprived smokers and non-smokers performed equally well. The next test was more complex. Non-smokers were faster, but under the stimulation of nicotine, active smokers were faster than deprived smokers. In the third test of short-term memory, non-smokers made the fewest errors, but deprived smokers committed fewer errors than active smokers. In the fourth test, non-smokers were the best and deprived smokers bested those who had smoked a cigarette just before testing. As the tests became more complex, non-smokers performed better than smokers by wider and wider margins.