Caffeine's overwhelming popularity as a stimulant is merited, according to a study that looked at its effects on proofreading.
The study, published in the Journal of Experimental Psychology: Applied, examined two groups of college students, one where individuals consumed half a cup of coffee a day (about 50 milligrams (mg) of caffeine) on average and the other where they averaged about three cups a day (roughly 300mg).
"Caffeine has become the most prevalently consumed psychostimulant in the world, but its influences on daily real-world functioning are relatively unknown," the researchers wrote.
Individuals in the first experimental group were randomly given pills that contained 0mg, 100mg, 200mg or 400mg of caffeine. After 45 minutes, they were asked to edit a one page news story in five minutes that contained various spelling and grammar mistakes.
The second group took the same randomly assigned caffeine doses and then performed the same five minute proofreading task.
The groups performed similarly in all areas except what the study called "complex global errors." These verb tense and subject-verb agreement issues were more consistently corrected by participants who had been given more caffeine before the test. The effect was especially pronounced in the first group, the low consumers.
"We demonstrate that caffeine has differential effects on error detection and repair . . . and this relationship is closely tied to caffeine's effects on subjective arousal state," the researchers wrote.
The findings indicate that caffeine is most effective when used irregularly. The low consumers' accuracy topped off at 200mg of caffeine whereas the high consumers improved to the same level at 400mg.
Additionally, the study supports a popular theory that central nervous system stimulants interact with the right hemisphere of the brain to impact language-related functions.
Broadly speaking, the researchers aim in conducting the study was to, "[understand] the relationships between caffeine consumption and real-world cognitive functioning."
Though the study did show a positive correlation between caffeine intake and proofreading accuracy, it is not in itself definitive.
The sample size was very small, with 36 students in the first group and 38 in the second, and all participants were in approximately the same age group and overall health.
The researchers found that caffeine consumption did not help the students catch misspelled words or incorrect use of homophones.
Further inquiry will be needed to more broadly determine caffeine's impact on human performance in different situations and with different types of tasks.
