Only one corner of the mouth is pulled up and back on one side.

• The eyes remain neutral.

• This is the only expression that forms on only one side of the face.

• It can vary in intensity. The depth of the emotion can vary. At its strongest, one eyebrow may lower.

• The lower eyelid can rise on the same side.

Only one corner of the mouth is pulled up and back on one side.

• The eyes remain neutral.

• This is the only expression that forms on only one side of the face.

• It can vary in intensity. The depth of the emotion can vary. At its strongest, one eyebrow may lower.

• The lower eyelid can rise on the same side.

Paul Eckman outlined six basic human emotions that have been hardwired into the human brain over countless generations. As such, these emotions are known to elicit the strongest and most instinctual responses out of all possible emotions. These include surprise, sadness, happiness, fear, disgust, and anger.