Child and Adolescent Development Progression:
An Interactive Timeline and Guide
by Dr Philip Tam and Amanda J. Pooley
In this interactive, easy-to-use, visual timeline, the Child and Adolescent Research Institute has built an evidence and clinically based guide of the key developmental aspects, risks, and clinical issues for the first 18 years of life. A full reference list and further resources are provided at the end of the timeline.
• ensure broadly normal milestones. • positive attachment experiences are vital for healthy development • promote fine motor skills via toys, writing, painting • ensure trust and empathy from primary caregivers
• infants and toddlers need 11 to 14 hours sleep in a whole day • usually have two naps in daytime • this decreases to one afternoon nap from age 2
• show good role modelling from infancy. • always prioritise child over ‘checking phone’. • shared family time. For example, meals and outings without any devices present.
• learning difficulties and language delay • early signs of autism possible • trauma and disrupted attachment • excess temper tantrums/infant anxiety • sleep and feeding disorders (may be related to anxiety or physical problem)
• avoid or minimise all device usage, including television. • do not use devices as a ‘pacifier’ or to aid sleep/settling. • may, from age of two, use screens as tool to aid communication (For example, with relatives).
• ensure broadly normal milestones • support independent activities of daily living. For example, dressing, toileting, fine motor skills • individual personality and characteristics will emerge. Encourage independent and social play/interactions • promote an ‘imaginative play space’ that is not screen/device based
• continue to show good role modelling. • be attuned to child’s needs and their developing personality • continue to have daily screen free family time, and promote shared family activities • avoid being over controlling, except around safety and clear screen use limits
• learning difficulties and language delay • autistic and sensory behaviours may emerge more • selective mutism and anxiety • attention deficit and hyperactivity disorder (ADHD) • behaviour and oppositional problems • obsessive compulsive disorder (OCD)
• many have own device • clear rules on usage and limits • no devices in bedroom overnight • have 1 to 2 hours screen free time prior to sleeping • aim to have more time on non screen activities in the day than screen based activities
• able to do all activities of daily living independently and without prompting • fine and gross motor skills developed • specific skills or interests may be emerging. For example, sporting, musical • personality and temperament style now more clear
• able to sleep through the night • should require minimal or a little amount of ‘settling’ prior to sleep • requires 9 to 11 hours total amount • no nap in the day • keep devices out of bedroom if possible
• continue to display positive role modelling • promote clear, regular structures through the day, including weekends • support individual interests, especially external/non screen activities • avoid anger, demeaning or criticising behaviours
• learning difficulties and language delay may become more prominent. • eating disorders may show early signs • depression and anxiety • ADHD may worsen if not treated • obsessive compulsive disorder (OCD) • behavioural and oppositional problems • very rarely, signs of bipolar or psychosis may emerge
• most have their own devices, for personal and schooling use • maintain clear screen time guidelines and limits, both for gaming and social media • promote device usage in a common space and not bedroom • no devices in bedroom overnight • at least 1hr of screen free time prior to sleeping
• fully or nearly independent in activities of daily living • more responsible for own belongings • personality nearly fully formed, although may still change • may have own part time job and finances • still needs positive role modelling from all caregivers
• need 8 to 10 hours unbroken sleep • device free for 1 hour pre bedtime • should not feel tired in the day if getting adequate sleep • get specialist assistance if sleep problems persist
• continue to be a positive role model, including around device usage • still need a caregiver to provide support and a ‘safe haven’ • clear rules and expectations for the household, made in advance, will reduce future conflict and tensions • if tensions persist, consider engaging in Family Therapy or similar
• depression and anxiety • early signs bipolar disorder and psychosis • drug use and addictions • gender identity and dysphoria • eating disorders (mainly in females) • conduct disorders and aggressive behaviour (mainly in males) • ADHD may persist, or may begin to improve
• almost all now have own devices, for education and personal usage • allow device usage in bedroom • can have devices overnight, if can show controlled use • 1hr of screen free time prior to sleeping is advised • online gambling also an emerging issue
Screen Use Guidelines
It is likely that even infants will be exposed vicariously to various screens in home. For example, seeing parents/sibling using devices. Even very young infants can ‘pick up’ on environment cues and show modelling and learning, so it is very important to model positive behaviour. For example, when at a park, avoid or minimise using your device when the child can observe you.
Guidelines: A child of this age should not have their own device and no device should be used as a ‘pacifier’ as he/she will associate devices with calming down and this worsens future emotion regulation. A child of this age should never use a device without adult supervision and use should be limited to 1 to 2 hours per day. Only allow a child to use a device for ‘positive technology’ use, for example, talking with distant relatives. Children of this age should not be left alone with devices.
Emerging Mental Health Disorders
Seeing a purely psychiatric illness in this age group is rare. Where they do occur, they are usually as a result of an attachment/bonding disruption with the caregiver. For example, due to post natal depression, as a result or trauma or neglect, or due to a developmental issue, such as learning delay, deafness, foetal alcohol syndrome. It is vital that, if any concerns arise, professional help is sought promptly, such as from a developmental paediatrician or an experienced early childhood psychologist. Caregivers may notice unusual bonding/attachment patterns from an early age in infancy, such as avoiding or disliking being cuddled, being very hard to settle, or showing poor eye contact. This may be an early sign of an autistic disorder, or associated with cognitive delays. Again, early assessment from a specialist is important.
Emerging Mental Health Disorders
Many mental health disorders can begin to emerge at this age, especially those associated with neurological or neurodevelopmental problems. Some behaviours may be noticed mainly, or only, in the preschool or the school setting (For example, in the classroom) and not when at home, and some may manifest across all settings. This is important, when making an accurate diagnosis. Any major, or worsening concerns should be noted by the caregiver, and consideration given to requesting appraisal by a developmental specialist, such as a child psychologist, paediatrician, or psychiatrist.
Family Guidelines and Modelling
Children in this group will be commencing school, and learning to play with others without an adult caregiver always present. This could be both ‘parallel’ play, or shared, interpersonal play. For example, via structured games and use of toys. Both types of play are important and should be encouraged, especially as the child commences schooling. Caregivers should begin to notice personality styles and characteristics or temperament evolving, and they should be aware of these often subtle differences. There is thus no single, ‘correct’ way to play and to interact; however, major difficulties in social interaction may require a specialist assessment if they persist or worsen over time. For example, the child never engages freely in shared play, or shows clear anxiety/distress when encouraged to engage in shared play. Children in this age range are also highly attuned to the behaviours and actions of others, and may ‘model’ their own behaviours on what they see adults doing, such as a caregiver always using their own device, in the presence of the child. Children in this range are forming their ‘internal working models’ of how to engage positively and to interact, whether in a familiar setting or in a new one.
Screen Use Guidelines
Increasing numbers of children in this age group will have their own digital device, usually a tablet computer, more often than a phone. It is important, at the point of purchase, to outline and discuss clear rules and expectations around using the device. Many primary schools are utilising computers and devices in the classroom setting. Always discuss the specifics or this usage with the class teacher to familiarise oneself with the classroom ‘digital diet’, and be consistent with rules, time spent, limitations on use. Think of the ‘When, Where and What’ rules : When is the child allowed to use the device and for how long; Where are they allowed to access and use the device, including connecting to the Web; What are they allowed to do on their device, including what level of parental observation and supervision is expected. It is recommended that the child does not access their device when a caregiver is not present.
Most children in this group have regular access to a digital device, or have their own laptop, tablet or computer. It is likely they will be using their devices for much of homework and study, so it important to ensure that healthy digital habits are discussed and reinforced, especially if they use their device in the evenings. It is recommended that devices are not kept in the bedroom overnight, and that they have a ‘screen free time’ of at least 1 hour prior to the planned bed time. If there are persisting problems with falling asleep, awakening in the night, or feeling excessively tired in the mornings, then an assessment from a sleep specialist doctor is recommended.
Emerging Mental Health Disorders
Many important and long lasting mental health conditions can show ‘early signs’ at this age, both the ‘common’ mental health conditions such as anxiety, Attention Deficit Hyperactivity Disorder (ADHD), and depression, and the less common ones such as psychosis, eating disorders, and Obsessive Compulsive Disorder (OCD). There is clear evidence that effective treatment for any of these conditions, when done at this age, can have a significant and long lasting benefit on their future wellbeing. Thus, early detection and early intervention from a trained mental health specialist is strongly recommended. Behavioural and emotion regulation problems, such as anger management difficulties, tend to appear in this range as the personality type of the child becomes more prominent, and the demands and responsibilities upon the child increase as they move towards the end of primary school, move into high school, and go through puberty. It is noted that some mental illnesses are emerging at a younger age than 10 to 20 years ago, such as eating disorders, severe depression, and behavioural problems.
Screen Use Guidelines
The majority in this group now have their own device, or a device for use at school. Many are regularly on social media and are gaming. Note that many schools have a clear technology and device usage policy for this age range, as well as a ‘bring your own device’ requirement. Some States are limiting phone usage and access in primary school, for example, NSW, and these rules and expectations should be consistent and reinforced at home; try to mirror at home what is done in class to minimise confusion. It is hard to delineate what is ‘total screen time’ as education, social, TV, and gaming can all be device based. A useful ‘rule of thumb’ is that non-education screen time does not exceed the other activities in the day. In other words, a maximum of 2 to 3 hours of screen use on a week day during term time and 4 to 5 hours on a weekend or school holiday weekday.
A wealth of research indicates that teens in this age group regularly do not get sufficient sleep (well over 50%), which is highly concerning, given the link between poor sleep and developing cognitive, emotional and physical ailments. There are many reasons for this issue, and screen usage at bedtime or during sleep time is an important, and a fully remediable, reason. Devices are typically kept overnight in the teen’s bedroom, but clear parental monitoring and supervision of usage should continue. Repeated breaches of having a ‘healthy sleep hygiene’ routine, including digital distractions at bedtime, may require removal of devices from bedrooms. Many sleep disorders arise in this age group, so prompt appraisal by a sleep medicine specialist is recommended if problems persist.
Screen Use Guidelines
Nearly all children in this age range will own their own device, and it is important that caregivers still have a monitoring and supervisory role on usage, including time spent on gaming, on social media, and around online shopping and spending. Recent research also indicates that online gambling is an increasing problem, particularly in males, and strict monitoring of financial transactions is recommended. Privacy, inappropriate content sharing, and cyberbullying are also increasing and highly challenging concerns in this age group. The World Health Organisation (WHO) has recently classified ‘gaming disorder’ (commonly known as ‘internet addiction’) as a recognised mental health condition. An increasing number of mental health specialists are offering tailored treatment for this emerging condition.
Emerging Mental Health Disorders
This age range is often considered among the highest risk groups for developing, or suffering, mental illnesses. It is also one of the commonest groups for impulsive and self-destructive behaviours such as aggression, violence to others, and deliberate self-harm and suicide attempts. There is also evidence that the rates of mental illnesses in this group, notably anxiety, depression, eating disorders and self-harming, have been on the increase over the past two decades. The reasons for this are not fully understood, but are thought to include increased pressure and stress on adolescents, increased family breakdown and dysfunction, financial uncertainty, the commercialisation of childhood, and the pervasiveness of social media. High rates of processed food intake and a decrease in healthy, fresh food consumption (often leading to childhood obesity) are also known to increase rates of mental illness such as depression, anxiety and ADHD.
School psychologists are a vital resource to notice ‘early warning signs’ of distress, or to diagnose a mental health condition in a student, and they often play a key ‘gatekeeper role’ in referring on to an external psychologist or child psychiatrist.
Further Reading and References for the Timeline
2. Australian Bureau of Statistics (2010). Measures of Australia's Progress: Children and Mobile Phones, Retrieved from https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/1370.0~2010~Chapter~Children%20and%20mobile%20phones%20(220.127.116.11.2)
3. Australian Bureau of Statistics (2011). Australian Social Trends, Jun 2011. Retrieved from https://www.abs.gov.au/AUSSTATS/abs@.nsf/allprimarymainfeatures/F855C098BB0D7E84CA25825D00792A48?opendocument
4. Australian Communication and Media Authority (2019). Kids and mobiles: How Australian children are using mobile phones: Young and mobile. Retrieved from https://www.acma.gov.au/publications/2019-11/report/kids-and-mobiles-how-australian-children-are-using-mobile-phones
5. Haight, M., Quan-Haase, A., & Corbett, B. (2014). Revisiting the digital divide in Canada: The impact of demographic factors on access to the internet, level of online activity, and social networking site usage. Information, Communication & Society: Communication and Information Technologies Section (ASA), 17(4), 503-519.
6. Barnett, L.M., Lai, S.K., Veldman, S.L.C. et al. (2016). Correlates of Gross Motor Competence in Children and Adolescents: A Systematic Review and Meta-Analysis. Sports Med 46, 1663–1688 https://doi.org/10.1007/s40279-016-0495-z
7. Bowlby, J. (1958), The nature of the child’s tie to his mother. International Journal of PsychoAnalysis, XXXIX, 1-23.
8. Jones, S. (2007). Imitation in Infancy: The Development of Mimicry. Psychological Science, 18(7), 593-599.
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10. American Academy of Pediatrics (2016): Media and Young Minds – expert guidelines and recommendations
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12. Australian Sleep Health Foundation (2015). Sleep Needs Across the Lifespan – factsheet
13. UNICEF Global Report (2017). Children in a Digital World. UN publications, 2017.
14. eSafety Commisioner (n.d) . Be an eSafe kid. Sharing photos and my personal information online Retrieved from https://www.esafety.gov.au/kids/be-an-esafe-kid/sharing-my-personal-information-online
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28. NSW Government- Education (n.d) Review into the non-educational use of mobile devices in NSW Schools: POLICY Student Use of Digital Devices and Online Services Policy 2020. Retrieved from https://education.nsw.gov.au/content/dam/main-education/en/home/about-us/strategies-and-reports/our-reports-and-reviews/review-into-the-non-educational-use-of-mobile-devices-in-nsw-schools/Policy.pdf
29. Paruthi, S., Brooks, L., D'Ambrosio, C., Hall, W., Kotagal, S., Lloyd, R., . . . Wise, M. (2016). Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine. Journal of Clinical Sleep Medicine : JCSM : Official Publication of the American Academy of Sleep Medicine, 12(6), 785-786.
30. Ragusa, G. (2014). Gender, social media, games and the college landscape. In W. G. Tierney, Z. B. Corwin, T. Fullerton, & G. Ragusa (Eds.), Postsecondary play: The role of games and social media in higher education. Baltimore: JHU Press.
31. Rodríguez-Sánchez, A. M., Schaufeli, W. B., Salanova, M., & Cifre, E. (2008). Flow Experience among Information and Communication Technology Users. Psychological Reports, 102(1), 29–39. https://doi.org/10.2466/pr0.102.1.29-39
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