By Joseph Misulonas 

They say you shouldn't judge a book by its cover, but apparently when it comes to stoners it's usually true.

A new study published in in the journal Substance Use & Misuse found that people were more likely to correctly identify that a person in a photograph was a marijuana user than incorrectly guessing they did not use cannabis. Basically, if someone in a photograph is a stoner, people usually knew it.

“The present results provide evidence that individuals can discriminate between cannabis users and nonusers based on appearance alone,” the study said. “This ability is consistent regardless of the raters’ user status or gender, and age of the target.”

So how did people know if someone was a stoner? Well, nearly 50 percent of the participants in the study said it was a person's eyes (i.e. red or glossy) that helped them identify them as a marijuana user. Around 29 percent said the person's age was a factor, 25 percent said the person's facial expression, 20 percent said their smile, and 13 percent said the person's hair. 

Interestingly enough, 8.5 percent said a person's gender was a factor. And one thing the study noted was that non-cannabis users who were attempting to identify if someone was a stoner or not were more likely to think men were marijuana users than women.

So if you're wondering if people know you're a secret stoner, the answer is probably yes.