Much has been written about marijuana over years--both good and bad. Between buzz about legalization, side effects and potential health benefits, the emergence of a new breed of potrepreneur, and more, weed has been put right in the middle of the public eye.

But despite the fact that researchers often tout the relative harmlessness--and even the benefits--of marijuana use, a new study by University College London reveals that smoking cannabis may actually negatively influence short-term levels of motivation in humans.

Originally published in Pscyhopharmacology and later reported by Science Daily, the new findings demonstrate that even smoking one "spliff," a rolled mixture of tobacco and marijuana, is enough to make people less willing to work for money while "high."

For the research, which ultimately comprised two separate studies, 57 total participants were involved. In the first, 17 adults who reported occasional cannabis use inhaled cannabis vapor though a balloon. At a later date, the same group inhaled cannabis-placebo vapor. Right after, they were asked to complete real-life tasks for which they would be given money if completed. Even though 50% of participants chose to complete the task when sober, only 42% chose to do so when intoxicated.

While weed has been long rumored to have negative effects on one's motivation, the UCL study is the first definitive one to test using "an appropriate sample size and methodology," according to lead author Dr. Will Lawn at UCL Clinical Psychopharmacology.

In another part of the research study, it was also proposed that long-term cannabis users do not necessarily experience dampened motivation levels when not under the influence, despite popular belief that marijuana use results in lingering motivation problems. During this second study, 20 people who claimed to be addicted to marijuana were asked to perform the same motivation-testing task as those in the first study. Results showed that the reportedly cannabis-dependent volunteers were equally as motivated as the control group--that is, there was no lingering negative effect on motivation.

Although a longitudinal study is still required to confirm the hypothesis, the data the study has brought to light challenges the reigning opinions most people currently have on marijuana use.