Ever since the phrase "resting bitch face" (RBF) became popular in 2013, both celebrities and citizens have claimed to possess the expression, which refers to a neutral face that gives off a standoffish expression, according to the Daily Mail. Now, in order to explain the harsh perception of certain passive gazes, a team of researchers have partnered with Noldus Information Technology in order to use their Noldus FaceReader to analyze the various emotions of the human face.

The unique software, which is trained with over 10,000 images in order to identify specific emotional expressions, revealed the main characteristic of the RBF - higher levels of "unconscious, subtle contempt." Whether this is intentional or not, our brains are wired to pick up on these cues, leading us to take note of the RBF more so than other expressions.

"FaceReader is not detecting enough contempt to reflect true contempt, because these faces are not actually displaying contempt," the report reads. "It just looks like contempt to the viewer. Thus, it is the perception of that unconscious, subtle contempt expression that defines RBF."

Some of the characteristics of "unconscious, subtle contempt" include one side of the lip slightly receding, slight eye squinting, and a bit of a raising of the corners of the lips, The Independent reported.

Furthermore, despite the common association of the RBF with females, Abbe Macbeth, who participated in the research, claims that this is not a strictly female phenomenon, according to New York Magazine.

"That [smiling] is something that's expected from women far more than it's expected from men, and there's a lot of anecdotal articles and scientific literature on that," she said. "So RBF isn't necessarily something that occurs more in women, but we're more attuned to notice it in women because women have more pressure on them to be happy and smiley and to get along with others."

The findings were published in the Oct. 14 issue of Noldus.