Introduction to Developmental Psychology


Why Study Child Development?

  • Its own justification - watching children grow up
  • Intellectual reasons - answer questions - how we came to be as individuals and as a species
  • Practical reasons - raising children, social policies - e.g. labour laws, coroporal punishment (physical discipline for antisocial behaviour leads to further development of this)
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Intellectual Reasons

We are interested in both:

  • Human phylogeny - evolution of species
  • Human ontogeny - evolution of individual organism
  • Recapitulation theory - ontogeny is thought to recapitulate phylogeny - rudimentary gills on human foetuses - fish?

Studying development can provide unique insights into the evolution of the species

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  • Plato emphasised self-control and discipline
  • Aristotle was concerned with fitting child rearing to the needs of the individual child.
  • Plato believed that children are born with innate knowledge (nativist).
  • Aristotle believed that knowledge comes from experience (empiricist) - innate mechanisms to learn but learning produces development
  • The English philosopher, John Locke, like Aristotle, saw the child as a tabula rosa (blank state) and advocated first instilling discipline, then gradually increasing the child's freedom.
  • Jean-Jacques Rousseau, the French philosopher, argued that parents and society should give the child maximum freedom from the beginning.
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Research-Based Approaches

Emerged in the nineteenth century, in part as a result of two converging factors:

  • Social reform movements provided some of the earliest descriptions of the adverse effects that harsh environments can have on child development.
  • Charles Darwin's theory of evolution inspired research in child development in order to gain insights into the nature of the species (studied own son William).

Developmental psychology matured in the 20th century as a science.

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How To Study Development

The scientific method is an approach to testing belief which involves:

  • Choosing a question
  • Formulating hypotheses (i.e. an educated guess)
  • Testing those hypotheses
  • Forming conclusions
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Naturalistic Observation

e.g. trouble families


  • Good ecological validity - similar to real life
  • Can be used to study a range of behaviour


  • Hard to identify causal relationships - there are so many variables, it is often hard to know which ones influenced the behaviour of interest
  • Painstaking to administer - many behaviours occur only occasionally in everyday environments, so researchers' opportunities to study them through naturalistic observations are reduced.
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  • Allows full focus on the individual's behavioural pattern
  • Follow up questions can clarify an earlier response


  • Can be difficult to generalise beyond the individual case
  • Can be difficult to generate a causal argument
  • Accuracy may be limited - children may not understand, parents may succumb to social desirability bias
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  • Can directly test relationships between variables
  • Experimental control is relatively easy


  • "Artificial" technique - so perhaps lacking in ecological valdiity unless using "naturalistic" experiments
  • Sometimes are not possible due to ethical issues (or practical issues)
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Naturalistic Experiments

Although experiments have the unique advantage of allowing researchers to draw conclusions about the cause of events, their ecological validity can be questionable.

This provlem can be overcome by conducting naturalistic experiments, in which data are collected in everyday settings such as the home or in a special playroom at the testing lab.

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Cross-Sectional vs Longitudinal

Cross-Sectional Designs

  • Children of diffierent ages are compared on a given behaviour or characteristics over a short period of time.
  • Common

Longitudinal Designs

  • Used when children are studied twice or more over a long period of time.
  • Time-consuming
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Used to provide an in-depth depiction of processes that produce change

Provides insight into the process and emotional response to it

In this approach, children who are thought to be on the verge of an important developmental change are provided with heightened exposure to the type of experience that is believed to produce the change and are studied intensely while their behaviour is in transition (e.g. "counting on", Siegler and Jenkins, 1989)

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Ethical Issues

Researchers have a vital responsibility to:

  • Ensure the research does not harm the children physically or psychologically
  • Obtain informed consent from parents/guardians and the child (if they are old enough to understand)
  • Preserve the anonymity of the children who take part
  • Counteract any negative outcomes and correct any inaccurate impressions that arise during the study.
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How Infants Learn and Develop

Infants' brains experience synaptogenesis - density of synaptic connections between neurons greatly increases - before birth and many months afterwards

Rich learning environments lead to more synaptic connections

Infants learn an enormous amount in a very short space of time - a remarkable achievement enabled by a variety of learning mechanisms:

  • Habituation
  • Perceptual learning
  • Statistical learning
  • Classical conditioning
  • Observational learning
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Testing Learning

Learning begins prenatally

  • Newborn infants have been shown to recognise rhymes and stories presented before birth
  • Newborns prefer smells, tastes and sound patterns that are familiar because of prenatal exposure
  • How on earth can researchers know what newborns and older infants know?
  • How is it possible to test learning experimentally in an ethical way?
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A decrease in responsiveness to repeated stimulation reveals that learning has occurred.

  • The infant has a memory representation of the repeated, now-familiar stimulus
  • The speed with which an infant habituates is believed to reflect the general efficiency of the infant's processing of information.
  • Some continuity has been found between these measures in infancy and general cognitive ability later in life.
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Habituation - Looking

  • Maurer and Maurer
  • 3-months old - pictures of faces
  • At the 1st appearance of a photo of a face, her eyes widen and she stares intently
  • With 3 more presentations of the same picture, her interests wanes and a yawn appears - habituation
  • By its 5th appearance, other things are attracting the baby's attention.
  • When a new face finally appears, her interest in something novel is evident - dishabituation
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Habituation - Sucking

At 2 months of age (Eimas)

  • Allow infant to **** on a dummy that is connected to a computer and measure baseline ****ing rate
  • Present phoneme (/pa/) repeatedly
  • Sucking rate first increases and then infant habituates (i.e. returns to baseline ****ing rate)
  • Present new phoneme (/ba/)
  • Infant dishabituates (i.e. ****ing rate increases)
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Habituation - Heart Rate

  • At 32 weeks' gestation, the fetus decreases responses to repeated or continued stimulation
  • In 9th month of gestation, a fetus can habituate to one sound "babi"
  • Presentation of a novel stimulus "biba" causes foetus to dishabituate (Lecanuet et al.)
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Perceptual Learning

From the beginning, infants use their perceptual abilities to search for order and regularity in the world around them.

Perceptual learning is involved in many, but not all, examples of intermodal co-ordination

  • An infant does not need learning to detect standalone events (e.g. seeing and hearing a glass smash on the floor)
  • But only through experience does an infant learn what perceptual experiences go together (.e.g that a particular tinkling sound means a glass is being broken).
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Differentiation is the extraction from the constantly changing stimulation in the environment of those elements that are invariant or stable (Gibson)

  • For example, infants learn the association between certain facial expressions and tones of voice, even from different people

With age and experience, infants become increasingly efficient at differentiating and extracting information and can make finer and finer discriminations amongst stimuli.

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A particularly important part of perceptual learning is the infant's discovery of affordances, the possibilities for action offered by objects and situations (Gibson)

  • For example, an infant must learn that small objects (such as small shapes) afford picking up but larger ones (such as their container) do not, that round shapes afford pushing into the container through the round hole but square and star shapes do not, etc.
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Statistical Learning

Involves picking up information from the environment, forming associations amongst stimuli that occur in a statistically predictable pattern.

The natural environment contains a high degree of regularity and redundancy

Certain events occur in a predictable order, certain objects appear in the same time and place, certain stimuli co-occur in patterns

From quite early on, infants are sensitive to the regularity with which one stimulus follows another.

Infants as young as 2 months old are sensitive to the underlying statisitcal patterns in shape sequences, even when the shapes are presented one at a time.

It takes 8-month-old infants only two months to pick a word out of a stream of speech (Saffran et al.)

Statistical learning may be critical to language learning.

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Classical Conditioning

A form of learning that consists of associating an initially neutral stimulus with another stimulus that always evokes a reflexive response

Plays a role in infants' everyday learning about the relations between environmental events that have relevance for them.

It is thought that many emotional responses (both positive and negative) are initially learned through classical conditioning.

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Classical Conditioning - Stimuli

Classical conditioning involves an unconditioned stimulus (UCS) that reliability elicits a reflexive, unlearned response - an unconditioned response (UCR).

Learning or conditioning can occur if an initially neutral stimulus, the conditioned stimulus (CS), repeatedly occurs just before the unconditioned stimulus.

Gradually, the originally reflexive response - the learned or conditioned response (CR) - becomes paired with the initially neutral stimulus.

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Classical Conditioning - Pavlov's Dogs

In a famous example of classical conditioning, the Russian researcher Ivan Petrovich Pavlov began to train dogs using classical conditioning.

Dogs naturally salivate (UCR) when presented with food (UCS).

Pavlov presented dogs with a ringing bell (CS) before feeding

After a few repetitions, the ringing bell alone was enough to make the dogs salivate (CR)

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Instrumental Conditioning

Also called operant conditioning

Involves learning the relation between one's own behaviour and its consequences.

Most organisms will tend to repeat behaviours that lead to rewards and will tend to give up behaviours that fail to produce rewards or lead to punishment

Note that the behaviour must occur before it can be instrumentally conditioned

Conditioning occurs when an infant learns the contingency relation between his/her behaviour and the resulting consequences

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Types of Instrumental Conditioning

Some conditioning strengthens behaviour (increases the likelihood that the behaviour will occur)

  • Positive reinforcement means behaviour is reliably rewarded by a positive experience (for strong ethical reasons, most instrumental conditioning research with infants involves positive reinforcement) - infants as young as 2 months old learn the contigency relation between kicking a leg and making a mobile move within minutes and deliberately and joyfully increases their rate of foot kicking - Rovee-Collier
  • Negative reinforcement means behaviour is reliably rewarded by stopping an ongoing negative experience.

Other conditioning weakens behaviour (decreases the likelihood that the behaviour will be repeated)

  • Punishment means behaviour is reliably penalised by a negative experience.
  • Extinction means behaviour is neither reliably rewarded or penalised (i.e. nothing happens)
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Infants may also learn there are some situations over which they have no control

  • Infants of depressed mothers tend to smile less and show lower levels of positive affect than do infants of non-depressed mothers.
  • This may be because infants of depressed mothers have learned there is no contingency relation between such friendly displays and being rewarded by their preoccupied parent (Campbell et al.)
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Observational Learning

Some have reported that the ability to imitate others may be present early in life, although in an extremely limited form.

For example, reports of newborns sticking out their tongues after watching an adult model repeatedly perform this action.

BUT recent work from Oostenbroek et al. suggests that young infants cannot imitate (which has been further debated)

Imitation is quite robust in older infants.

By 15 months, infants can imitate actions they have seen an adult perform on television.

In choosing to imitate a model, infants appear to pay attention to the reason for the person's behaviour (i.e., the person's intention).

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Imitating Intentions

When 18-month-olds see a person apparently try, but fail, to pull the ends off a dumbbell, the infants imitate the action by actually pulling the ends off.

  • They perform the action the person intended to do, not what the person actually did (Meltzoff).

They do not imitate a mechanical device at all.

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