Editing Human behavior (section)

=== Age ===
{{Further|Ageing}}
[[File:Drummer girl (24186419196).jpg|thumb|An infant engaging in play in [[Los Angeles]], California (2015)]]
;Infants
[[Infant]]s are limited in their ability to interpret their surroundings shortly after birth. [[Object permanence]] and understanding of [[motion]] typically develop within the first six months of an infant's life, though the specific cognitive processes are not understood.{{Sfn|Bremner|Wachs|2010|pp=234–235}} The ability to mentally categorize different concepts and objects that they perceive also develops within the first year.{{Sfn|Bremner|Wachs|2010|pp=264–265}} Infants are quickly able to discern their body from their surroundings and often take interest in their own limbs or actions they cause by two months of age.{{Sfn|Bremner|Wachs|2010|pp=337–340}}

Infants practice [[imitation]] of other individuals to engage socially and learn new behaviors. In young infants, this involves imitating [[facial expression]]s, and imitation of tool use takes place within the first year.{{Sfn|Bremner|Wachs|2010|pp=346–347}} Communication develops over the first year, and infants begin using [[gesture]]s to communicate intention around nine to ten months of age. Verbal communication develops more gradually, taking form during the second year of age.{{Sfn|Bremner|Wachs|2010|pp=398–399}}

;Children
Children develop [[fine motor skill]]s shortly after infancy, in the range of three to six years of age, allowing them to engage in behaviors using the hands and [[eye–hand coordination]] and perform basic activities of [[Self sufficient|self sufficiency]].{{Sfn|Woody|Woody|2019|pp=259–260}} Children begin expressing more complex emotions in the three- to six-year-old range, including humor, empathy, and altruism, as well engaging in creativity and inquiry.{{Sfn|Woody|Woody|2019|p=263}} [[Aggression|Aggressive]] behaviors also become varied at this age as children engage in increased physical aggression before learning to favor diplomacy over aggression.{{Sfn|Woody|Woody|2019|p=279}} Children at this age can express themselves using language with basic grammar.{{Sfn|Woody|Woody|2019|pp=268–269}}

As children grow older, they develop [[emotional intelligence]].{{Sfn|Charlesworth|2019|p=346}} Young children engage in basic social behaviors with [[Peer group|peers]], typically forming friendships centered on play with individuals of the same age and gender.{{Sfn|Woody|Woody|2019|p=281}} Behaviors of young children are centered around play, which allows them to practice physical, cognitive, and social behaviors.{{Sfn|Woody|Woody|2019|p=290}} Basic self-concept first develops as children grow, particularly centered around traits such as gender and ethnicity,{{Sfn|Charlesworth|2019|p=343}} and behavior is heavily affected by peers for the first time.{{Sfn|Charlesworth|2019|p=353}}

;Adolescents
[[Adolescents]] undergo changes in behavior caused by [[puberty]] and the associated changes in [[hormone]] production. Production of [[testosterone]] increases [[sensation seeking]] and [[Reward system|sensitivity to rewards]] in adolescents as well as [[aggression]] and [[risk-taking]] in adolescent boys. Production of [[estradiol]] causes similar risk-taking behavior among adolescent girls. The new hormones cause changes in emotional processing that allow for close friendships, stronger motivations and intentions, and [[adolescent sexuality]].<ref>{{Cite journal |last1=Peper |first1=Jiska S. |last2=Dahl |first2=Ronald E. |date=2013 |title=The Teenage Brain: Surging Hormones&nbsp;– Brain-Behavior Interactions During Puberty |journal=Current Directions in Psychological Science |language=en |volume=22 |issue=2 |pages=134–139 |doi=10.1177/0963721412473755 |issn=0963-7214 |pmc=4539143 |pmid=26290625}}</ref>

Adolescents undergo social changes on a large scale, developing a full self-concept and making autonomous decisions independently of adults. They typically become more aware of social norms and social cues than children, causing an increase in [[self-consciousness]] and [[adolescent egocentrism]] that guides behavior in social settings throughout adolescence.<ref>{{Cite journal |last1=Choudhury |first1=Suparna |last2=Blakemore |first2=Sarah-Jayne |last3=Charman |first3=Tony |date=2006 |title=Social cognitive development during adolescence |url=https://academic.oup.com/scan/article/1/3/165/2362733 |journal=Social Cognitive and Affective Neuroscience |volume=1 |issue=3 |pages=165–174|doi=10.1093/scan/nsl024 |pmid=18985103 |pmc=2555426 }}</ref>