(extraverted Feeling cue)
ESFJ, ENFJ, ISFJ, INFJ, ENTP, ESTP, INTP, ISTP
ESFJ, ENFJ, ISFJ, INFJ, ENTP, ESTP, INTP, ISTP
Key characteristics:
- Expresses outwards horizontally
- Corners of the mouth stretch sideways due to peripheral muscle tension (along the sides of the face)
- In older subjects with increased skin laxity, curved creases may appear along the sides of the face and outer corners of the eyes while smiling
- Lack of central muscle tension (along and around the nose and upper lip)
- Mouth does NOT move up to any significant extent
Hypothetical functions and mechanisms:
- Appealing to the emotions of others is evolutionarily advantageous since one is more likely to be accepted within the tribe where one has access to shared resources and help. Perhaps the clear lateral movement is an exaggerated way to show good will by showing more teeth. In humans, angry facial expressions typically show less upper teeth (see image below)
- The risorius (see image below) muscle's function is to pull the corners of the mouth laterally. The muscles of the body become stronger or more active the more we use them and facial muscles are no exception. Over time, this may become stronger or more active through habitual use, so the spreading mode of smiling gets cemented similar to how good or bad posture gets cemented