Researchers from the University of California, Santa Barbara have been studying the effects of craving cigarettes on people's concentration. They studied 44 heavy smokers, none of whom had had a cigarette in the last six hours before the start of the study. Some of them were allowed to smoke during the experiment while others were not. The participants had to read pages from War and Peace and press a button marked ZO every time they felt themselves zoning out (drifting off). They were also prompted by a message on screen asking them if they were zoning out. After 30 minutes they took a reading comprehension test. The participants who had not been allowed to smoke and who were craving cigarettes were three times as likely to drift off during the study but were no more likely to admit to it.
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