Editing Developmental psychology (section)

===Infancy===
{{Main|Infant and child psychology|Infant cognitive development}}
From birth until the first year, children are referred to as [[infant]]s. As they grow, children respond to their environment in unique ways.{{sfn|Berk|2012|p={{pn|date=January 2025}}}} Developmental psychologists vary widely in their assessment of infant psychology, and the influence the outside world has upon it.

The majority of a newborn infant's time is spent sleeping.<ref>{{cite journal |last1=Hirshkowitz |first1=Max |last2=Whiton |first2=Kaitlyn |last3=Albert |first3=Steven M. |last4=Alessi |first4=Cathy |last5=Bruni |first5=Oliviero |last6=DonCarlos |first6=Lydia |last7=Hazen |first7=Nancy |last8=Herman |first8=John |last9=Katz |first9=Eliot S. |last10=Kheirandish-Gozal |first10=Leila |last11=Neubauer |first11=David N. |last12=O’Donnell |first12=Anne E. |last13=Ohayon |first13=Maurice |last14=Peever |first14=John |last15=Rawding |first15=Robert |last16=Sachdeva |first16=Ramesh C. |last17=Setters |first17=Belinda |last18=Vitiello |first18=Michael V. |last19=Ware |first19=J. Catesby |last20=Adams Hillard |first20=Paula J. |title=National Sleep Foundation's sleep time duration recommendations: methodology and results summary |journal=Sleep Health |date=March 2015 |volume=1 |issue=1 |pages=40–43 |doi=10.1016/j.sleh.2014.12.010 |pmid=29073412 }}</ref> At first, their sleep cycles are evenly spread throughout the day and night, but after a couple of months, infants generally become [[diurnal animal|diurnal]].<ref name=":2">{{cite book |last1=Patel |first1=Aakash K. |last2=Reddy |first2=Vamsi |last3=Shumway |first3=Karlie R. |last4=Araujo |first4=John F. |title=StatPearls |date=2025 |publisher=StatPearls Publishing |chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK526132/ |chapter=Physiology, Sleep Stages |pmid=30252388 }}</ref> In human or rodent infants, there is always the observation of a diurnal cortisol rhythm, which is sometimes entrained with a maternal substance.<ref name=":3">{{Cite journal |last1=Iwata |first1=Osuke |last2=Okamura |first2=Hisayoshi |last3=Saitsu |first3=Hiroki |last4=Saikusa |first4=Mamoru |last5=Kanda |first5=Hiroshi |last6=Eshima |first6=Nobuoki |last7=Iwata |first7=Sachiko |last8=Maeno |first8=Yasuki |last9=Matsuishi |first9=Toyojiro |date=Jan 2013 |title=Diurnal cortisol changes in newborn infants suggesting entrainment of peripheral circadian clock in utero and at birth |journal=The Journal of Clinical Endocrinology and Metabolism |volume=98 |issue=1 |pages=E25–32 |doi=10.1210/jc.2012-2750 |pmid=23150686 |doi-access=free }}</ref> Nevertheless, the circadian rhythm starts to take shape, and a 24-hour rhythm is observed in just some few months after birth.<ref name=":2" /><ref name=":3" />

Infants can be seen to have six states, grouped into pairs:
* quiet sleep and active sleep ([[dream]]ing, when [[REM sleep]] occurs). Generally, there are various reasons as to why infants dream. Some argue that it is just a psychotherapy, which usually occurs normally in the brain. Dreaming is a form of processing and consolidating information that has been obtained during the day. Freud argues that dreams are a way of representing unconscious desires.<ref>{{cite journal |last1=Zhang |first1=Wei |last2=Guo |first2=Benyu |title=Freud's Dream Interpretation: A Different Perspective Based on the Self-Organization Theory of Dreaming |journal=Frontiers in Psychology |date=2018 |volume=9 |page=1553 |doi=10.3389/fpsyg.2018.01553 |pmid=30190698 |pmc=6115518 |doi-access=free }}</ref>
* quiet waking, and active waking
* fussing and [[crying]]. In a normal set up, infants have different reasons as to why they cry. Mostly, infants cry due to physical discomfort, hunger, or to receive attention or stimulation from their caregiver.<ref>{{Cite web |date=2020-12-07 |title=Soothing a crying baby |url=https://www.nhs.uk/conditions/baby/caring-for-a-newborn/soothing-a-crying-baby/ |access-date=2023-12-28 |website=nhs.uk |language=en}}</ref>

====Infant perception====
Infant perception is what a newborn can see, hear, smell, taste, and touch. These five features are considered as the "five senses".<ref>{{cite book | vauthors = Bee D, Boyd H |title=The developing child |publisher=Pearson Education |location=Upper Saddle River, N.J. |isbn=978-0-205-25602-0 |page=36 |edition=13th|date=2011-12-12 }}</ref> Because of these different senses, infants respond to stimuli differently.<ref name="bremner" />

* [[Visual perception|Vision]] is significantly worse in infants than in older children. Infant sight tends to be blurry in early stages but improves over time. Color perception, similar to that seen in adults, has been demonstrated in infants as young as four months using habituation methods.<ref name="butterworth" /> Infants attain adult-like vision at about six months.{{sfn|Berk|2012|p=191}}
* [[Hearing (sense)|Hearing]] is well-developed prior to birth. Newborns prefer complex sounds to pure tones, human speech to other sounds, mother's voice to other voices, and the native language to other languages. Scientist believe these features are probably learned in the womb.{{sfn|Berk|2012|p=151}} Infants are fairly good at detecting the direction a sound comes from, and by 18 months their hearing ability is approximately equal to an adult's.
* [[Olfaction|Smell]] and [[taste]] are present, with infants showing different expressions of disgust or pleasure when presented with pleasant odors (honey, milk, etc.) or unpleasant odors (rotten egg) and tastes (e.g. sour taste). Newborns are born with odor and taste preferences acquired in the womb from the smell and taste of amniotic fluid, in turn influenced by what the mother eats. Both breast- and bottle-fed babies around three days old prefer the smell of human milk to that of formula, indicating an innate preference.{{sfn|Berk|2012|p=150}} Older infants also prefer the smell of their mother to that of others.<ref name="butterworth" />
* [[Haptic perception|Touch and feel]] is one of the better-developed senses at birth as it is one of the first senses to develop inside the womb.<ref>{{cite book | vauthors = Feldman RD, Papalia DE |title=A child's world: infancy through adolescence |year=2010 |publisher=McGraw-Hill |location=New York |isbn=978-0-07-353204-2 |page=57 |edition=12th}}</ref>  This is evidenced by the [[primitive reflexes]] described above, and the relatively advanced development of the [[somatosensory cortex]].<ref name="Slater">{{cite book |title=Introduction to Infant Development | vauthors = Slater A, Lewis M |isbn=978-0-19-928305-7 |publisher=OUP |location=Oxford |year=2006}}</ref>
* [[Pain]]: Infants feel pain similarly, if not more strongly than older children, but pain relief in infants has not received so much attention as an area of research.<ref name="MatthewMatthew">{{cite journal | vauthors = Mathew PJ, Mathew JL | title = Assessment and management of pain in infants | journal = Postgraduate Medical Journal | volume = 79 | issue = 934 | pages = 438–443 | date = August 2003 | pmid = 12954954 | pmc = 1742785 | doi = 10.1136/pmj.79.934.438 }}</ref> Glucose is known to relieve pain in newborns.<ref name="DilenElseviers">{{cite journal | vauthors = Dilen B, Elseviers M | title = Oral glucose solution as pain relief in newborns: results of a clinical trial | journal = Birth | volume = 37 | issue = 2 | pages = 98–105 | date = June 2010 | pmid = 20557532 | doi = 10.1111/j.1523-536X.2010.00389.x }}</ref>

====Language====
{{Main|Language development}}
Babies are born with the ability to discriminate virtually all sounds of all human languages.{{sfn|Berk|2012|p=189}} Infants of around six months can differentiate between [[phoneme]]s in their own language, but not between similar phonemes in another language. Notably, infants are able to differentiate between various durations and sound levels and can easily differentiate all the languages they have encountered, hence easy for infants to understand a certain language compared to an adult.<ref>{{cite book |doi=10.1111/b.9780631203124.1996.x |title=The Handbook of Child Language |date=1996 |isbn=978-0-631-20312-4 |editor-last1=Fletcher |editor-last2=MacWhinney |editor-first1=Paul |editor-first2=Brian }}{{pn|date=January 2025}}</ref>

At this stage infants also start to [[Babbling|babble]], whereby they start making vowel consonant sound as they try to understand the true meaning of language and copy whatever they are hearing in their surrounding producing their own phonemes.

In various cultures, a distinct form of speech called "babytalk" is used when communicating with newborns and young children. This register consists of simplified terms for common topics such as family members, food, hygiene, and familiar animals. It also exhibits specific phonological patterns, such as substituting alveolar sounds with initial velar sounds, especially in languages like English. Furthermore, babytalk often involves morphological simplifications, such as regularizing verb conjugations (for instance, saying "corned" instead of "cornered" or "goed" instead of "went"). This language is typically taught to children and is perceived as their natural way of communication. Interestingly, in mythology and popular culture, certain characters, such as the "Hausa trickster" or the Warner Bros cartoon character "Tweety Pie", are portrayed as speaking in a babytalk-like manner.<ref>{{cite book |doi=10.1111/b.9780631203124.1996.00014.x |chapter=Phonological Development |title=The Handbook of Child Language |date=1996 |last1=Menn |first1=Lise |last2=Stoel-Gammon |first2=Carol |pages=335–360 |isbn=978-0-631-20312-4 }}</ref>