THE STUDY

Hart and Risley
(1995)
have carried out a unique
long-term investigation
of the direct effects
of home experiences
on children’s development.

They looked at the verbal interactions
between parents and their children
and analysed monthly,
1-hour tape recordings taken
from the age of about
10 months to 3 years.

There were 42 families involved and
these were classified
into three main groups of:
professional families,
where parents were college professors
(generally equivalent
to UK lecturers),
working class families,
and families who were on welfare support.

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FINDINGS

Hart and Risley’s first main findings
were of progressive differences
in the language abilities
of the children from the three types
of home background.

Although children from all
of the groups started
to speak at about the same time
and also developed good structure
and use of language,
their vocabulary as measured by the
number of different words used,
varied significantly.

By age three,
the observed cumulative vocabulary
for children in the professional families
was about 1,100,
for the working class families it was about 750,
and for the welfare families it was just above 500.

These developments happened alongside
major differences
in the language experiences
of the children studied.

In professional families,
children heard an average of
2,153 words per hour;
in working class families
1,251 words per hour
and in welfare families only
616 words per hour.

Extrapolating these figures
to cover 4 years of experience
would give 11 million words heard
by a child in a professional family,
6 million for a child
in working class family
and 3 million for a child
in a welfare family.

Hart and Risley also identified
a number of key features
of positive verbal interaction
which could be applied
to all of the families.

They found that these could be grouped
into five main categories of parent behaviours:

• ‘They just talked’
-generally using a wide vocabulary.

•‘They tried to be nice’
-using high rates of approval
and few prohibitions.

•‘They told children about things’
- language had a high information content.

•‘They gave children choices’
- children were asked about things,
rather than simply being directed.

•‘They listened’
- responding to what children said
rather than just telling them
what to do or making demands.

When these were combined together
into a single index of parenting,
Hart and Risley found that
at the end of the study
this had a strong relationship
with children’s general linguistic
and intellectual development.

RELATIONSHIP BETWEEN
PARENTING INDEX AND
IQ SCORES AT AGE 3 YRS.

Source: Hart and Risley
(1995)

The correlation between these two variables is .78,
which means that
the parenting measures are able
to account for 59 percent
of the cognitive accomplishments
of children at this age.

Given that this was based
on only about 26 hours of observations
for each child
and that it missed out the first 10 month period,
it seems likely that the true relationship
between upbringing and ability
could be even greater.

If this is the case,
then although genetics may still have some effect,
its role would have
to be much less that traditional estimates
have usually indicated.

A detailed analysis
of socio-economic status
of the families as assessed by parental occupation,
was only able
to account for 29 percent
of the variance in I.Q.

SCORES

As can be seen from the graph above,
working class children
covered the range of attainments
and this was largely related
to the quality of parental involvement –
the child with the highest ability came
from a working class home,
which also had the highest quality
of interactions.

Socio-economic status therefore only appears
to be a relatively crude proxy
for what actually happens
within individual families
although those with the highest levels
of deprivation
(on welfare)
were more consistent in scoring
at a low level.
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INTERPRETATIONS

When a group of 29 of the children
were followed up
at ages 9 to 10,
the earlier parenting measures
were still able
to account for 61 percent
of the variance in measures of verbal ability.

This is a very high value
for such long term prediction and
is probably due
to the fact that parenting styles
were relatively stable and continued
to have consistent effects
on children’s development.

THE EARLY I.Q.

measures at 3 years old
had no discernible influence
on later measures of academic achievement and this study
therefore supports the belief
that quality of parenting
is the key feature which determines general cognitive abilities
as well as academic attainments.

One possible alternative interpretation
of the above findings is that children who were inherently more intelligent
evoked more verbal interaction
from their parents,
or that intelligent parents
(who talk a lot)
simply have more intelligent children.

That is to say,
genetic effects could have been
the underlying basis
of the observed differences in performance.

This does not seem likely however
as the detailed observations indicated
that parents largely set up and
directed verbal interactions,
and were not just responding
to their children’s initiatives.

Also,
if intelligence were simply inherited,
then children’s verbal abilities
and the interactions
between parents and their children
would arise directly from this.

This is not supported by the fact that,
as found in studies
such as Bouchard and McGue
(1981),
the correlation between
the measured intelligence of parents
and of their children
(.42)
only accounts
for about 17 percent of the variance.

This is outweighed by the fact that
in Hart and Risley's study,
the correlation between
parental behaviour and children’s
verbal abilities accounts
for 59 percent of the variance.

It therefore seems much more likely that
it is parental behaviour which causes
children’s verbal development,
and that the correlation between
parent-child intelligence
could be secondary
to this in some way.
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REFERENCES

Bouchard, T. and McGue, M.
(1981)
Familial studies of intelligence:
a review.

Science, 212, 1055-1059.

Hart, B. and Risley, T.
(1995)
Meaningful Differences
in Everyday Parenting and
Intellectual Development
in Young American Children.

Baltimore: Brookes.

Martyn Long March 2002
(All ideas and opinions expressed
in this article are entirely my own
and do not necessarily represent
those of my employer)