Once upon a time, although it seems barely credible to us now, we were all children.
We gurgled, we cried, we laughed, we explored, we fell down, and we had very little idea about the journey on which we had just embarked.
Barring mishap, over the first few years of our lives we developed memory, language, self-concept, cognitive, social and emotional abilities.
We took our first steps towards our future selves.
Child psychology — or, more broadly, developmental psychology — is not just the study of children, it is the study of you and me and how we came to be this way.
Just as discovering your history can teach you about the future, so developmental psychology shows us what we once were and even what we will become.
Here are 10 classic developmental psychology studies that have illuminated crucial areas of childhood development.
Each one is a piece in the jigsaw puzzle that is ourselves, and each one reminds us, through examining just one piece, how aspects of experience we now take for granted were once so complex.
Click the links for a more extensive description of each developmental psychology study.
1. Infant memory develops very early on
Some argue it’s impossible for us to remember anything much from before around two to four years of age.
Others think our memories can go way back – perhaps even to before birth.
The question of ‘infantile amnesia’ is thorny because it’s hard to test whether adults’ earliest memories are real or imagined.
What psychologists have done, though, is examine the emergence of memory in our first few years with a series of now classic experiments in developmental psychology.
These have found that our memory systems actually work quite well from very early on.
Infants’ memories also seems to work in much the same way as adult memories – it’s just that infant memories are much more fragile.
2. Developmental psychology: when the self emerges
To this day the ‘mirror test’ remains the best developmental psychology experiment yet developed for examining the emergence of self-concept in infants.
Most people look out for number one, themselves, which makes it strange to think that there was ever a time when we had no concept of ‘me’.
A simple study dating from the early 70s suggests that before the age of around two years old we can’t recognise ourselves in the mirror.
Because of this study, and the many variations in developmental psychology that have followed, some claim that it isn’t until our second birthday that our self-concept emerges.
3. How children learn
A classic study of childhood learning suggests true understanding comes from letting go of established preconceptions.
How children revise their understanding of the world is one of the most fascinating areas of developmental psychology.
But it is not just relevant to children; we all have to take on new concepts from time-to-time – even though they may not be as profound as the origin of the species.
It’s tempting to think that learning is largely about memory – especially since in the bad old days of education learning was largely accomplished by rote.
However, the idea of ‘mental models’ suggests children create, and then test, mental models of the way the world works in order to build up our understanding, and that is how children learn.
4. Attachment styles in developmental psychology
Attachment styles analyse how people respond to threats and problems in their personal relationships.
People who find relationships difficult often become unable to participate in the ordinary give-and-take of everyday life.
They may become hostile towards others, have problems in education as well as a greater chance of developing psychiatric disorders later in life.
These difficulties sometimes have their roots in the most important early relationships, evidenced in attachment styles.
It’s no wonder that developmental psychologists are so interested in the first relationships we build with our primary caregivers.
These attachment styles are likely to prove a vital influence on all our future relationships, including those with our spouse, our workmates and our own children.
While you can’t blame everything on your parents, early relationship attachment styles are like a template that we take forward with us in life.
5. Infants imitate others when only weeks old
One of the most basic forms of social behaviour is copying another person.
Although imitation is something we adults take for granted, it’s actually a pretty demanding process for a young infant.
At the heart of imitation is understanding the difference between yourself and others – something that famous Swiss child psychologist Jean Piaget thought didn’t emerge immediately in infants.
Consequently, he argued that infants could not imitate others until they were 8 to 12 months of age.
However, now some researchers think tiny infants who are between 12- and 21-days-old can imitate others.
6. When children can simulate other minds
Theory of mind is when we can put ourselves in other people’s shoes to try and imagine their thoughts, intentions and possible actions.
Without the ability to simulate what other people are thinking we would be lost in the social world.
The emergence of theory of mind in children is a vital developmental milestone; some psychologists think that a failure to develop a theory of mind is a central component of autism.
Some developmental psychology studies suggest that at about 4- to 6-years old a range of remarkable skills start to emerge in young children that are vital for their successful functioning in society.
They begin to understand that others can hold false beliefs, they themselves can lie, and that others can lie to them — they have a theory of mind.
7. Object permanence in developmental psychology
Object permanence, or object constancy, in developmental psychology is understanding that things continue to exist, even if you cannot seem them.
Research in developmental psychology has found that infants as young as 3.5 months seem to have a basic grasp of object permanence.
It appears that young infants are not necessarily trapped in a world of shapes which have little meaning for them.
Instead, they seem to be intuitive physicists who can carry out rudimentary reasoning about physical concepts like gravity, inertia and object permanence.
8. How infants learn their first word
An infant’s very first step in their year-long developmental journey to their first word is perhaps their most impressive.
This first step is discriminating and categorising the basic sound components of the language they are hearing.
To get an idea how hard this might be think about listening to someone speaking a language you don’t understand.
Foreign languages can sound like continuous streams of noise in which it’s very hard to pick up where one word starts and another word begins.
Research in developmental psychology finds that until about 11 months of age infants are masters of discriminating phonemes used in all different types of languages.
But after 11 months infants settle down with one set of phonemes for their first language, and lose the ability to discriminate the phonemes from other languages.
9. Play and developmental psychology
The pioneering developmental psychologist Lev Vygotsky thought that, in the preschool years, play is the leading source of development.
Through play children learn and practice many basic social skills.
They develop a sense of self, learn to interact with other children, how to make friends, how to lie and how to role-play.
The classic developmental psychology study of how play develops in children was carried out by Mildred Parten in the late 1920s at the Institute of Child Development in Minnesota (Parten, 1933).
She closely observed children between the ages of 2 and 5 years and categorised the types of play.
She found six different types of play, ranging from solitary, through associative to cooperative
10. Piaget’s developmental psychology theory
Jean Piaget was a developmental psychologist whose four-stage theory, published in 1936, has proved extremely influential.
Piaget’s four stages of development theory has the dubious claim to fame of being one of the most criticised psychological theories ever.
From the sensorimotor stage, through the pre-operational stage, the concrete operational stage and the formal operational stage, his theory attempts to describe how childhood development progresses.
However, Piaget’s experiments and theories about how children build up their knowledge of the world have faced endless challenges, many of them justified.
Read on about them here.