Attachments

Attachments Revision



The Essential Guide!!

Name FOUR things about



Attachment

Attachment – What is it?

• 1. An affectional tie between two people or

animals

• 2. A two-way process that endures over time

• 3. Leads to certain behaviours such as:

Clinging – Proximity seeking – Crying -

Smiling

• 4.Serves the function of protecting the infant

or young animal

(Mary Ainsworth 1970)

What do we mean by these

Behaviours?

• And how are they essential to the

development of a healthy creature?

• They are all features of a Secure Attachment

• Proximity Seeking

• Secure Base Behaviour

• Separation Anxiety

• Stranger Anxiety

Key Terms

• Proximity Seeking – Staying close to the

attachment figure

• Secure Base Behaviour – Regularly returning

to an attachment figure when exploring

• Separation Anxiety – Anxiety at being apart

from an attachment figure

• Stranger Anxiety – Anxiety in the presence of

strangers

• They are all essential for survival!

Why are Psychologists so



interested in

Attachment?

Why are Psychologists so

interested in Attachment?

• Because ALL psychologist believe that the

attachment we form with our primary carer

(usually our mother) forms a TEMPLATE for

all future relationships - with friends, with

teachers, and, in the future, with husbands and

wives and in turn, OUR FUTURE CHILDREN.

If our attachment with our mother is not good,

psychologists believe our whole life could be put

at a disadvantage.

Explain Attachment using the



Learning Theory

Explanations of Attachments N0. 1

• LEARNING THEORY

• All behaviour is learnt rather than inborn

• Children are born blank slates and everything

they become is dependent on what they

experience

• Learning theory is put forward by

BEHAVIOURIST psychologists who say that

all behaviour, including attachment is learnt

by:

• Classical and Operant Conditioning.

Classical Conditioning – Learning by Association

Operant Conditioning – learning by Reward

(Reinforcement) and Punishment

• Classical Conditioning – food produces

pleasure. “Feeder” (mother) becomes associated

with food/pleasure so baby becomes attached to

her.

• Operant Conditioning – food is the primary

reinforcer, “feeder” becomes the secondary

reinforcer – both food and mother reduce

discomfort, and therefore reward the infant and

so the baby becomes attached to the mother.

Evaluating the Learning Theory

(Sometimes called the “Cupboard Love” Theory!)

• Strengths 

• Learning theory suggests that the attachment develops

between infant and carer because the carer provides food.

And it’s true – we do learn through association and

reinforcement.

• Weaknesses 

•  We do learn through association and reinforcement but

it may not be the food that is the reinforcer, it may be the

responsiveness and attention of other carer.

•  If the learning theory is true:

• How come babies often develop strong attachments to

people who don’t feed them?

• The Harlow Monkey Experiment.

Name, date and describe Two

research studies which cast

doubt on the

Learning Theory

The Harlow Monkey Experiment

• Harry Harlow, 1959 conducted research in to learning

using young rhesus monkeys, kept alone.

• He created two “mothers”, one with made of wire but a

full feeding bottle of milk, and the other wrapped in a

soft cloth but without food.

• According to the learning theory the young monkeys

should have become attached to the wire mother.

• In fact the monkeys spent most of their time with the

cloth-covered mother and would cling to it, especially

when frightened.(a proximity-seeking behaviour,

characteristic of attachment)

Schaffer and Emerson 1964

• Whilst the Harlow Monkey experiment used animals,

the above study used human infants.

• 60 babies (from mainly working-class Glasgow homes)

were observed for a year.

• Schaffer & Emerson found that infants were not most

attached to the person who fed them but became

attached to the person who was most responsive to them

and who interacted most with them.

• This reinforces the Harlow Monkey experiment and

suggests that “cupboard love” is not likely to be the best

explanation for attachment, although association and

reinforcement may be part of the story.

The Evolutionary



Perspective - Bowlby’s

Theory of Attachment

Explain Bowlby’s theory of

Attachment using the following

terms

• Survival Value Reproductive Value

• Innate Drive Imprinting

• Pre-programmed Social Releasers

• Adaptive Sensitive Period

• Monotropy Template

• Internal Working Model

• Continuity Hypothesis Responsive Mother

Bowlby’s Theory of Attachment

• Bowlby’s theory is an Evolutionary theory

• In his view attachment is a behaviour that has evolved

because of its survival value and, ultimately, its

reproductive value.

• According to Bowlby, children have an innate drive to

become attached to a caregiver because attachment has

long-term benefits. He proposed that normal psychological

development requires the development of a secure

attachment between a baby and its main carer.

• He also proposed the concept of imprinting – an innate

readiness to develop a strong bond with a mother figure.

Pre-programming!!

• John Bowlby said that babies are pre-

programmed to behave in ways that encourage

adult attention

• He called these behaviours social releasers

• These include “cute” behaviours such as

smiling and cooing and are the child’s

contribution towards an attachment. The

mother’s contribution is that she must respond

and react to these behaviours

• He suggests these instinctive behaviours

enhance survival and and are protective for the

infant. He called these behaviours ADAPTIVE.

Sensitive Period

• Bowlby said there is sensitive period from when

the baby is born to around the age of 2, when the

baby is programmed to form a special attachment.

He called this monotropy. If something happens

to damage or break this attachment, the child may

develop and insecure attachment its development

may well be damaged.

• For a secure attachment to take place, the child’s

main carer (usually the mother) needs to be

attentive, SENSITIVE and responsive to the

child’s needs, during this sensitive period.

More about Bowlby’s theory

• Bowlby said the child develops a model or

template from the attachment with its mother

which influences all future relationships and

future parenting style. It is a prototype of all

future relationships. He called this the internal

working model.

• The internal working model indicates a big link

between early emotional experiences and later

relationships. He called this the continuity

hypothesis – the idea that early experiences

continue to influence throughout life.

Give some  Strengths of

Bowlby’s theory of Attachment

Evaluating Bowlby’s theory of

Attachment - Strengths

• It is considered the dominant explanation of how

and why attachment develops.

•  Imprinting is supported by Lorenz’s ducks

•  Bowlby suggests that attachment evolved to as

an aid to survival. If this is true then attachment

and caregiving behaviours should be universal, in

all cultures, despite differences in child-rearing

practices. There is evidence to support this.

(Tronick et al 1992)

Give Some Research Evidence



Supporting Bowlby’s Theory



Research Evidence for Bowlby’s Theory

•  Schaffer and Emerson, 1964, observed that

strongly attached infants had mothers who

responded quickly to their demands and who

offered the child the most interaction whereas

weakly attached infants had mothers who failed

to interact with them.

•  The Minnesota longitudinal study (Sroufe et al

2005) followed children from infancy to

adolescence and found continuity between their

early attachment styles and their later emotional

and social behaviour. This supports the

continuity hypothesis.

And the Harlow Monkey

Experiment

•  Supports Bowlby’s theory that a

responsive mother is needed for good,

lifelong psychological health. The

monkeys were not only psychologically

damaged, but proved incapable of

becoming effective and loving parents,

themselves.

Give some Weaknesses  of



Bowlby’s Theory

More Evaluation of Bowlby’s theory

Weaknesses

•  The idea that attachment behaviours have

evolved to promote child development has good

face validity. But evolutionary ideas are very

difficult to test and so difficult to prove or

disprove.

•  Bowlby’s theory focuses on the role of the

mother. There is evidence that in two-parent

families, the quality of attachment of the father

can also have a big effect on the child’s

development. (Grossmann and Grossmann,

1991)

Give an Alternative Explanation

for



Attachment

An Alternative Explanation

• A key feature of Bowlby’s theory is the continuity

hypothesis – the idea that there are continuities between

early attachment and later social/emotional

development. However Kagan, 1984 put forward

• The Temperament Hypothesis, in which he proposed

that we are all born with our distinct, innate

temperament, and it is this that is the big factor in

determining our attachment style and our subsequent

emotional and social development. In other words, to

some extent, our development is pre-determined by our

genetic makeup. And there is evidence to support this---

---

Belsky and Rovine 1987



• Assessed babies aged one to three days

old and found a link between certain

psychological behaviours and later

attachment types. They found that

infants who were calmer and less anxious

were more likely to be securely attached.

Name and date the procedure

which aimed to test the nature

of attachment systematically.

The Strange Situation – Which is

Ainsworth and Wittig 1969







• Laboratory Procedure using

• Observation Techniques

• Designed to measure the security of

attachment a child displays towards its main

care giver

• What is being assessed?

• Secure base behaviour, proximity seeking,

separation anxiety, stranger anxiety, response

on being reunited with care giver.

What is the Procedure of the



Strange Situation

The Strange Situation –it gets its name from the fact

that the baby is placed in an unfamiliar – that is, a

strange room

Stage

Situation Designed to measure

The child and carer are placed in an empty room.

1.

The child is free to explore-encouraged if necessary Proximity-seeking and

2. secure base behaviour

A stranger enters, greets the carer and attempts to Stranger Anxiety

3. play with the child

The carer leaves the child with the stranger Stranger anxiety +

4. Separation distress

The carer re-enters and the stranger leaves Reuniting response

5.

The carer leaves the child alone Separation distress

6.

The stranger re-enters Stranger Anxiety

7.

The stranger leaves and carer re-enters Reuniting response

8.

What were the findings of the



Strange Situation

Behaviours displayed by infants in The

Strange Situation (Ainsworth et al 1978)

Secure Insecure Insecure Insecure Avoidant/

attachment Resistant.

Avoidant Resistant(Ambivalent) “Disorganised”

(Type B) (Type A) (Type C) (Type D)

Willingness to Alternate

HIGH HIGH LOW between A & C

explore

Stranger Often prefer

HIGH LOW HIGH strangers’ company

Anxiety

Separation Reasonably INDIFFERENT DISTRESSED Alternate

Anxiety easy to soothe Between A & C

Behaviour at re- ENTHUSIASTIC AVOIDS SEEKS AND Often afraid of

Union with carer CONTACT REJECTS carer

% of infants in Minority of

66% 22% 12%

this category Infants display

this disorganised

behaviour

How did Mary Ainsworth

account for the

Variations in attachment

types?

Explaining Attachment Types

• Mary Ainsworth believed variation in

attachment types is a result of the main

carer’s behaviour towards the child.

Maternal Sensitivity Hypothesis

• High levels of maternal sensitive responsiveness =

Secure attachment

• Mothers who “pick up” signals and respond =

Secure attachment

What is Secure Attachment?



What did Ainsworth believe caused

it?

Secure Attachment

• This is a strong and contented attachment

of an infant to its caregiver, which

develops as a result of sensitive

responding by the caregiver to the

infant’s needs. Securely attached infants

are comfortable with social interaction

and intimacy. Secure attachment is

related to healthy subsequent cognitive

and emotional development.

What is Insecure Attachment?

What causes it? What can it lead

to?

What is the difference in the various

insecure attachment types?

What is Insecure Attachment?

• Insecure attachment – This is a form of attachment

between infant and caregiver that develops as a result of

the caregiver’s lack of sensitive responding to the infant’s

needs. It may be associated with poor subsequent

cognitive and emotional development.

• Insecure Avoidant Type A– children who avoid social

interaction and intimacy with others.

• Insecure Resistant Type C – Children who both seek and

reject intimacy and social interaction.

• Insecure Disorganised Type D– Children whose

behaviour patterns are inconsistent and a mix of types A &

C.

What Research Methods



Were Used?

Research Methods used

• The research room was a novel environment

• A 9 X 9 foot square marked off in to 16 squares to help

the recording of the infant’s movements

• Research methods used were Laboratory procedure

using covert and controlled observation

• Using covert observation (One-way mirrors were used to

prevent participants being aware they were being

observed). Knowing your behaviour is being observed is

likely to alter it.

• It used Controlled observation because it involved structuring the

behaviour of the participants as well as the observers –the

participants had to follow 8 episodes and the observers had a

checklist of 5 behaviours that they had to rate every 15 seconds.

Give 2 Criticisms of the



Strange Situation

1. Is it Valid?

• Validity – means are we measuring what we meant to

measure. This lab procedure intended to measure the

attachment types of children. Did it? A criticism is that

it only measured the strength of one particular

relationship, and this wasn’t necessarily with the main

carer.

• Others say this doesn’t matter, since Bowlby said the

relationship with the main carer becomes internalised

and is reflected in all other relationships-so if the child

appeared insecurely attached, even if the main carer

wasn’t present during the Strange Situation, the

attachment type given to the child is a reflection of what

is happening at home with the main carer.

2. Is it Ethical?

• The intention of the Strange Situation was

to cause mild distress. Is this acceptable?

Ainsworth claimed that the whole procedure

was not intended to be any more disturbing

than ordinary life experiences, yet in

episode 6 (The carer leaves the child alone)

20% of infants reportedly “cried

desperately”.

And what did Hazen and Shaver

1987 find about Adult Romantic

Relationships in their



Newspaper Love Quiz?

Love Quiz Findings

Attachment Secure adults Insecure- Insecure-

type avoidant adults resistant adults



Current love Relationships Fearful of Preoccupied

experiences closeness by love

Are

Positive



Attitudes Trust others Love is not Fall in love

towards love and believe in lasting nor easily but

enduring love necessary for have trouble

happiness finding true

love

Name and date the Research that

aimed to study

Cross-Cultural Attachments

What were the Aims and

Procedure?

Cross-cultural patterns of attachment –

Van Ijzendoorn and Kroonenberg,

1988

• Aim – To investigate global attachment

patterns

• Procedure - This was a meta-analysis (the

data from 32 Strange Situation studies from

eight countries was collated and analysed)

What were



The Findings?

Findings

In all countries, secure attachment was the most common –but…….!!!!!!!!!!!

Secure Attachment (Type B) -Most common in all cultures. The

The Lowest proportion was in China (50%)

The Highest (approx 75%) –GB & Sweden.

------------------------------------------------------------------------------

Avoidant Attachment (Type A) More common in W. Germany

than other western countries.

Very rare in Israel and Japan.

---------------------------------------------------------------------------------------------

Resistant Attachment (Type C) - Common in Israel, China &

Japan.

Lowest proportion was in Scandinavian countries such as Sweden

What Conclusions



Can be drawn?

Conclusions

• Globally, secure attachment was the most common

and we could conclude, the “best” for healthy

social and emotional development.

• The variation in percentages, particularly between

types A and C suggest that child-rearing practices

in different countries may affect the attachment of

babies -------and/or

• It may be that the Strange Situation does not work

well in all cultures.

Give a Criticism of the



Cross-cultural Strange Situation

Big Criticism: Is the Strange

Situation Culturally Biased?

• The Strange Situation was developed in the

U.S, an individualist country.

• But in Japan for example, which is a collectivist

country, the cultural norm is for mothers and

babies to rarely be separated, which means we

might expect to see high levels of separation

anxiety and might explain the high % of Type C

in the SS. Many of the differences in the cross-

cultural SS concern collectivist countries.

More on Culture Bias

• Rothbaum et al 2000 said that attachment theory and

research is not relevant to other cultures because it is

so rooted in American culture. Why did they say

this? Here are two examples.

• 1. The Continuity Hypothesis (Ainsworth said that

those infants who are securely attached grow up to

be socially and emotionally competent adults)-

people who are independent and able to express

their emotions. BUT!! ….. In Japan being a

socially and emotionally competent adult means

being group orientated and someone who is able to

inhibit (not show) their feelings.

We must be so careful when

interpreting data!!

• What we call “avoidant” behaviour in the

UK and USA, might well be called

“independent” in Germany, an

individualist country, but where

independence is very highly valued. And

just look at the graph and you will see that

there are a higher proportion of type “As”

in Germany.

Methodological Issues (can also be used

for evaluation)

• 1. Meta-analysis (the results of 32 S.S studies were

analysed)

• 2. Substantial study and large sample size (over

2000 babies)

• 3. But half of the 32 studies studied were carried

out in the US, reflecting the dominance of US in

psychology studies.

• 27 were carried out in individualistic cultures

• Only 5 in collectivist cultures, implying that the

sample was not truly representative.

More Methodological Issues

• 4. Ainsworth’s Strange Situation was

developed in the US so we can only

make valid interpretations in cross-

cultural studies if we really understand

the attitudes to child-rearing in that

culture.

What does all this mean?

• When looking at attachment behaviours cross-

culturally, some might question Bowlby and

Ainsworth’s view, that attachment is a universal

factor in human development. However, whilst

there are differences, and to some extent,

attachment theory is culture-bound, the

impressive fact is that in in all 8 countries

involved in the meta-analysis of the Strange

Situation, secure attachment was the most

common, by far, and we could conclude, the

“best” for healthy social and emotional

development.

• Certainly research has shown that secure

attachment is associated with good psychiatric

health in adulthood.

What is Disruption of the



Attachment Bond?

Disruption of the Attachment

Bond

• Deprivation - temporary or

permanent disruption of the attachment

bond.

• This means there was an attachment to

start with but it’s been broken in some

way, perhaps due to hospitalisation or

death of the mother.

Identify some effects that

disruption of attachment has on

A child’s social and emotional

development

Provide Research support

Effects of Disruption.

• Robertson and Robertson observed John and Laura

sufferering when they experienced physical disruption

with no substitute emotional care. But Jane, Thomas,

Lucy and Kate coped well when given substitute

emotional care at the Robertson’s home .

• Spitz and Wolf 1946, observed that 100 “normal”

children placed in an institution became severely

depressed within a few months.

• Skeels and Dye 1939, found that the intellectual deficits

of the institutionalised children recovered when they

were transferred to a home for mentally retarded adults

and given lots of T.L.C.

Evaluate the



Robertson Research

Evaluation of the Robertson

Research

• 1.  High validity – films were made of

John and Laura. These were naturalistic

observations in a realistic setting.

• 2.  Low validity – The conclusions were

based on case studies of only a few

children, who may not have been typical of

the majority of children.

So what factors effects whether



A child will recover from

Disruption?

Bowlby concluded..

• Children cope better and recover better

from disruption if they were securely

attached to start with.

• Bowlby 1956 –: 60 children under the age

of 4 who had TB

• They were put in a hospital, no substitute

emotional care was given.

• When assessed in adolescence. 63% were

maladjusted, leaving 37% who were not.

So What is



Privation?

Privation

• Privation – when there was

never any attachment bond to

begin with.

• This can be due to extreme abuse

or Institutional care, or in rare

cases, children kept in total

isolation.

Can you describe some real-life

cases?

• Genie and the Czech twins, handout N0. 8

• AlSO it is essential to revise The Affects

of Privation, Hodges and Tizard, 1989

also Handout No. 8

What do most of the studies on

Privation

Show?

The Findings suggest..

• The findings suggest that early privation

had a negative effect on the ability to form

relationships even when children were

given good subsequent care.

• This supports Bowlby’s view that the

failure to form attachments during the

sensitive period has an irreversible effect on

emotional development.

What are some of the effects of



Privation and

Institutionalisation?

The Effects are….

• Attachment Disorder – There are two types:

• Reactive or inhibited – when the child is unable to

cope in most social situations

• Disinhibited - Over-friendly and attention seeking to

people the child hardly knows.

• Deprivation Dwarfism – Gardner 1972, suggests

emotional disturbance may effect the production of

growth hormones which may explain why children in

institutional care tend to be physically small.

The research suggests that some



Children are able to

recover from privation.

How come?

Evaluation

• Some research suggests that children who do

not form an attachment within the sensitive

period are unable to recover.

• But this is not true of all children. How come?

• One reason is because we really don’t know

enough about the children in the studies. For

example in the Hodges and Tizard study -Why

were some adopted and others not? Could it be

that some were easier children to start with –

that’s why they were chosen for adoption, so of

course, their outcomes were better!

1.Why are we interested in day

care?

2. What is Day care?

Day Care is -

• A form of temporary care (not all day and not

all night) that is not provided by family

members and takes place outside of the home.

• Why are we interested in day care?

• Because day care involves the very thing

psychologists are interested in – disruption of

the attachment bond with the primary carer

which may affect the child’s social and

emotional development.

What do we mean by



Social Development?

Social Development



• The development of sociability,

learning to relate to others and

acquiring appropriate

knowledge & skills of how to

integrate socially.

You may be asked for research

evidence on social development

and aggression in children

In Day Care.

Here it is.

Research on the impact of Day Care

• Negative effects on social development    

• Bowlby said prolonged separation from mother figure could cause

long-term maladjustment. Many studies of day care have

supported this.

• Violata & Russell, 1994 did a meta-analysis of the findings of 88

studies of day care and concluded that regular day care of more

than 20 hours p/w had a negative effect on the social and emotional

development of young children.

• Increased Aggressiveness (NICHD 2003)  

• The NICHD in America started a longitudinal study in 1991, using

1000 children from mixed backgrounds and locations. Assessed

aged 5, the data found that, irrespective of quality, the more time

spent in day care, the more aggressive and disobedient they were

deemed to be by adults. Belsky, 2007 looked at the same children

at the end of primary school education, and still found these

children more aggressive than children who hadn’t been in day

care.

On the other hand…

• This same NICHD study found that a mother’s

sensitivity to her child is a better indicator of

whether a child had behavioural problems, than

was time in child care. Sensitive mothering was

linked to fewer problem behaviours. Higher

maternal education and family income also

predicted lower levels of problem behaviours.

So this same data suggests that children’s

development is more strongly affected by factors

at home, than by day care.

Peer Relationships   

• Bowlby’s theory of attachment and his

Continuity Hypothesis predicts better peer

relationships for securely attached children.

There is evidence that children in day care are

less securely attached. Belsky & Rovine, 1988,

assessed infants in day care for more than 20

hours p/w using the Strange Situation. They

found these children were more likely to be

insecurely attached than children at home. We

could hypothesise that their peer relationships

would also suffer too.

On the other hand…  

• Day care allows children to develop social strategies,

such as the ability to negotiate and make friends. Field,

1991, found the amount of time in full-time day care

was positively correlated to the number of friends the

children had once they were at school.

• However we can’t assume that experiences in day care

cause later sociability - there is a link; it could be that

shy and unsociable children have mothers who are like

that too (temperament is inherited) and these mothers

prefer to stay at home to care for their children. The

outgoing mothers send their outgoing children to day

care, which explains why they’re more sociable.

Mediating Factors

• A mediating factor is something that connects two other

things, in this case it is intervening between the effects

of day care and social development.

• Quality of care - A NICHD study (1997) reported that

low-quality day care was associated with poor social

development.

• Individual Differences – The above NICHD study

found that insecurely attached children did less well in

day care. On the other hand, Egeland & Hiester, 1995,

found that insecurely attached children did best in day

care and it was the securely attached ones who became

aggressive. This might be due to the fact that the

insecurely attached children needed the care and

attention that they weren’t getting at home.

More Mediating Factors

• Child’s age and number of hours

• Gregg et al, 2005, found that the negative effects

of day care were more likely to be found in

children placed in day care before they were 18

months old. On the other hand, Clarke-Stewart

et al, 1994, found no difference in attachment

between spending a lot of time in day care (30

hours or more a week from 3 months of age).

Implications of research into

attachment and day care

• Now we must look at how research translates into the

practical issues of childcare provision in the UK. What advice

can be given to governments and to parents?

• Attachment Research

• In previous handouts we discovered that James and Joyce

Robertson (remember little John and Laura in hospital?) found

that the negative effects of emotional disruption could be avoided

if substitute emotional care was provided. This entailed specific

adults spending time with the children and responding to their

needs in a sensitive way in the same way that a primary care

giver would. The characteristics of quality day care do just

that and psychologists have identified the following key

characteristics needed for high-quality day care.

Characteristics of high-quality day care

• 1. Low child-to-staff ratio – NICHD study 1999,

identified this was absolutely necessary for high-quality

care.

• 2. Minimal staff turnover – Schaffer, 1998, identified

consistency of care as one of the most important factors in

high-quality care.

• 3. Sensitive emotional care – The NICHD study found

that 23% of infant-care providers give highly sensitive

care, 50% give moderately sensitive care and 20% are

emotionally detached from the infants in their care.

• 4. Qualified Staff – Sylva et al 2003, reported that the

higher the qualifications of the staff, the better the

outcome for the children in terms of their social

development.

What are the most important

factors to consider

When looking at Day Care?

The most important factors in day care with regard to the

welfare of children are:

• 1. QUALITY of the day care Research indicates positive effects for good

quality day care but negative effects for poor quality care. Quality

encompasses having sufficient stimulation, such as toys, sufficient and verbal

interactions between staff and children and sensitive emotional care to

provide a substitute for the break in the mother-child relationship. A rapid

turnover of staff can have a profound effect

• 2. CHILD-TO-STAFF RATIO This affects results tremendously as it

determines how much attention each child gets.

• 3. AGE of the children in care. Research indicates day care can be

detrimental to very young babies.

• 4. NUMBER OF HOURS the child is in care This has a big effect on

whether the bond with the primary care giver is disrupted.

• 5. The strength of the bond between each child and its primary care giver is

very important. Securely attached children are less likely to be affected by

the separation that day care entails. (The Strange Situation study)