<P> Even beyond the idea of eye contact, eyes communicate more data than a person even consciously expresses . Pupil dilation is a significant cue to a level of excitement, pleasure, or attraction . Dilated pupils indicate greater affection or attraction, while constricted pupils send a colder signal . </P> <P> Facial expression is used in sign languages to convey specific meanings . In American Sign Language (ASL), for instance, raised eyebrows combined with a slightly forward head tilt indicate that what is being signed is a yes / no question . Lowered eyebrows are used for wh - word questions . Facial expression is also used in sign languages to show adverbs and adjectives such as distance or size: an open mouth, squinted eyes, and tilted back head indicate something far while the mouth pulled to one side and the cheek held toward the shoulder indicate something close, and puffed cheeks mean very large . It can also show the manner in which something is done, such as carelessly or routinely . Some of these expressions, also called non-manual signs, are used similarly in different sign languages while others are different from one language to another . For example, the expression used for' carelessly' in ASL means' boring or unpleasant' in British Sign Language . </P> <P> The universality hypothesis is the assumption that certain facial expressions and face - related acts / events are signals of specific emotions (happiness with laughter and smiling, sadness with tears, anger with a clenched jaw, fear with a grimace, surprise with raised eyebrows and wide eyes along with a slight retraction of the ears, and disgust with a wrinkled nose and squinted eyes--emotions which frequently lack the social component of those like shame, pride, jealousy, envy, deferance, etc .) and are recognized by people regardless of culture, language, or time . The belief in the evolutionary basis of these kinds of facial expressions can be traced back to Darwin's The Expression of the Emotions in Man and Animals . Reviews of the universality hypothesis have been both supportive and critical . Work in 2013 by Nelson and Russell and Jack et al. has been especially critical . </P> <P> Ekman's work on facial expressions had its starting point in the work of psychologist Silvan Tomkins . Ekman showed that facial expressions of emotion are not culturally determined, but universal across human cultures . </P>

Who was the first researcher to suggest that facial expressions are pre-verbal