Facial expression responsible for controlling the expression differ in each case. Voluntary facial expressions are often socially conditioned and follow a cortical route in the brain. Conversely, involuntary facial expressions are believed to be innate and follow a subcortical route in the brain. Facial recognition is often an emotional experience for the brain and the amygdala is highly involved in the recognition process. The eyes are often viewed as important features of facial expressions. Aspects such as blinking rate can possibly be used to indicate whether a person is nervous or whether he or she is lying. Also, eye contact is considered
Facial width to height ratio the top lip. This can cause experimental error when working from photographs in historical studies due to facial expressions. Facial width to height ratio Facial width to height ratio (fWHR) is a measure derived from archaeological skull measurements. fWHR is not linked with adolescent testosterone, and has been proposed as: a predictor of aggression, cause of death by violence, and also with CEO success probability. While most studies have found some significance some have found little correlation. fWHR has also been used in primate studies with similar findings. Width is measured as upper bizygomatic width (the widest central bit of