title: Facial expression form and function.
abstract: From an evolutionary perspective, facial expressions would serve adaptive functions that promote genetic fitness. While many ideas have been proposed,1 the specific adaptive functions of expressing emotion on the face have largely remained untested since Darwin proposed a set of expressive functional principles over 130 years ago.2 Recently, we showed that expressions of fear and disgust alter the biomechanical properties of the face, such that fear increases while disgust decreases sensory exposure.3 Additional vector flow analyses presented here reveal that anger and surprise expressions may similarly be shaped by sensory contraction and expansion action tendencies. An examination of the temporal dynamics of sensory modulation may reveal a general principle shaping expressive form rather than a specific adaptation shaping fear and disgust. Furthermore, if sensory modulation is a general principle, this function should be present across species rather than only in humans. Although facial morphology differs across species, detailed examination of sensory intake in different species may reveal the origins of facial expressions inherited by humans.
authors.affiliation: Department of Psychology; University of Toronto; Toronto, Ontario Canada.
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Susskind
authors.forename: Adam K
authors.initials: AK
authors.lastname: Anderson
references.citation: Psychophysiology. 1993 May;30(3):279-86
references.pmid: 8497557
references.citation: Nat Neurosci. 2008 Jul;11(7):843-50
references.pmid: 18552843
references.citation: Am J Phys Anthropol. 2001;Suppl 33:3-24
references.pmid: 11786989
references.citation: Biol Psychiatry. 2002 Jun 1;51(11):859-66
references.pmid: 12022958
references.citation: J Pers Soc Psychol. 1985 Nov;49(5):1416-26
references.pmid: 4078682
references.citation: Psychol Rev. 1987 Jan;94(1):23-41
references.pmid: 3823304
references.citation: J Nonverbal Behav. 2007 Mar;31(1):1-20
references.pmid: 21188285
references.citation: Mol Psychiatry. 2001 Jan;6(1):13-34
references.pmid: 11244481
references.citation: J Anat. 2006 Feb;208(2):153-67
references.pmid: 16441560