FREE ESSAY ON COMPARISON BETWEEN ENVIRONMENTAL AND

COMPARISON BETWEEN ENVIRONMENTAL AND

Intelligence is the level of competence, ability to learn or to some people
it is how well an individual performs on an IQ test. The structure of
intelligence is best subdivided into two significant categories. They are
environmental and hereditary influences. 
Environmental differences can be divided into different factors. The
deprivation model of social class and intelligence consists of three
variables. These variables explain, in terms of environmental factors,
development and performance which are correlated with social status. 
The first of these variables consists of the combination of birth order,
nutrition, and prenatal care. Children who are first born, on average
score better on mental tests. There is a definite higher number of first
born children among higher socioeconomic groups as opposed to lower
socioeconomic groups. According to Bruce Eckland, children of higher
economic class tend to be brighter, on average, than children of lower
economic groups (65). Both prenatal stress and malnutrition, impair
development and are found much more frequently among lower
socioeconomic classes. According to Philip E. Vernon, the fetus can
have lack blood supply and growth of the fetus can be disturbed if the
mother takes certain drugs or suffers from certain diseases. Severe stress
on the mother can also be hazardous to the fetus (84). These conditions
expressed are both genetic and or resulting from environmental conditions
and are known to as constitutional factors. The second variable of the
deprivation model which helps exhibit differences in performance is the
cultural variable. It seems that lower socioeconomic classes experience a
unique pattern of behavioral and psychological traits which impair
development in children raised in these conditions. The last environmental
variable that accounts for differences in the cognitive development is the
social cultural variable. This variable includes deprivation which involves
socially structured inequalities in education and other social opportunities
for improving performance. Sidney W. Bijou states that in order to help
development, an ample supply of physical stimuli for cognitive
development is favorable along with the people who have to manage
these stimuli in contingent relationships after the birth of the child (230). 
Another environmental contribution to intelligence, which Bijou points out
is the availability of people who enhance opportunities for cognitive
development. These people have the job of shaping responses and for
bringing responses under stimulus control. Examples of this contribution
are conceptualizations and symbolizations. An unwanted contribution
would be some situation where there are people with marital discord or if
they are economically poor. Another contribution, explained by Bijou,
refers to the kinds of reinforcers in effect in cognitive situations. An
example of this contribution would be to use positive reinforcing
contingencies. A hampering situation would entail adults who use
aversive, neutral or random stimulus contingencies. The last of these
contributions refers to the schedules of reinforcement. These
contributions are categorized by a high number of people who schedule
contingencies of reinforcement in ways which maintain the cognitive
repertories acquired (230). Greenfield insists that people learn what they
need to accomplish a goal presented by the environment. The
specification of a particular set of goals by the environment not only
determines whether learning (255). In an experiment done on children,
Werner and Kaplan found out that variable verbal and action contexts
for a certain concept provide a way of generalizing that particular concept
by differentiating it from its context. Educationally this provides a wide
variety of action goals but even more important during the initial stage
instead of the later stages. This goal structure of the environment plays a
most important role in early life and then gradually declines in importance,
according to Patricia M. Green field. Greenfield also points out in a study
administered by Garves that middle class mothers give significantly more
positive feed back as opposed to lower class mothers who give a high
rate of negative feedback to their children. This scenario leads to feelings
of failure on the on the child's part. In other words, lower class mothers
believe that their goals cannot be attained, therefore giving way to a
feeling of discouragement and a response of negative feedback to their
children. This condition produces a lack of self-determination for the
lower class mothers which then in turn gives the child himself lack of
self-determination among other things. The home environment is also a
major factor for cognitive development. For starters, middle class
mothers may mothers may supply their children with an image of goals
towards which school is aimed. On the other hand lower class lower
class families seem to lack this positive feedback all together (252-260). 
Vernon states that child and parent interactions greatly influence the
cognitive growth of the child. Evidence of the previous is best
demonstrated in the work of Wulbert et al. Wulbert's experiments
compared the homes and mothers of twenty children who were retarded
in language and matched them with twenty normal children. The mothers
of the language retarded children had lower results in emotional and
verbal responsiveness and were more liable to punish their children than
the mothers of the other twenty normal children. Davis helps to illustrate
the views of Vernon. Davis described a girl who lived with a deaf mute
mother and did not develop any speech until she was moved from that
environment (p.131). Spitz, on the other hand, describes the effects of
early hospital upbringing but still helps support Vernon's views. He
studied infants who layed inside of their cribs with very little to look at
unless they were being fed or cleaned. Many of these infants died and all
of them, including those that died fell into a state of "apathy" (132). Both
of these studies support Vernon's views to the point that parent and child
interactions influence the child's cognitive development and growth ,
especially early in life. It seems that environmental differences play a
major role on the level of intelligence of an individual. Evidence of
environmental differences and its impact on intelligence is better illustrated
through higher IQ gains generated by the help of environmental
enrichment programs. These programs are more effective if they are
begun early in the life of the child. The reason behind that is that the
programs are better able to create lifelong changes in capacity to generate
and sustain responses to cognitive stimulation. These programs entail the
development of visual and auditory competence as well as encourage
attention and labeling which help cognitive development in children. 
Storfer notes the Drash and Stolberg experiment were it was found that
extraordinary high competence, emotional maturity and speech
development were attained by children as a result of an enrichment
program designed to modify the behavior of parents during the first year
of their child's life. The Stanford Binet scores of the four children
averaged one hundred fifty-five. 
Before we start to discuss Hereditary influences we must initially note
that both genetic or hereditary and environmental influences are equally
important, according to Dobzhansky. Many psychologist refer to
genetics as one of the major influences upon the level of individual
intelligence. Cancro states that the expression of "like produces like" is
an oversimplification with a strong basis underlying it. He points out that
offspring are more likely to be similar instead of unlike to their parents on
any genetically loaded trait. Cancro expresses that genetic as far as
heredity is concerned, is a distinct property of a population. 
This statement was made to note that inheritance is not a measure of an
individual or of the trait itself. Inheritance estimates the proportion of the
total variance in a proportion of the total variance in a population at a
particular point. Inheritance for intelligence usually falls between .70 to
.90, according to Cancro. This number depends on the population which
is being considered and on the specific test or method being used. The
Polygenic model suggests that both environmental and hereditarian
variables are required to explain differences in individual intelligence. The
Polygenic model is basically the same as the deprivation model from
environmental influences. The difference between these two model is the
fact that the Polygenic model introduces three new variables. The first of
these variables is the mid-parent and child's heredities which refer to the
genotypes of intelligence and furthermore result in "quantitive" variations
in cognitive functioning. The second variable of the Polygenic model is
referred to as mid-parent's and child's intelligence. The last variable of
the model is the child's heredity which stands for all the sources of
variance in the child's heredity accounted for by the mid-parent's
heredity. A connection between each variable supports the model. The
path is the connection and the path taken from parental intelligence to
social status is the most important. according to Eckland, it is the primary
link between genetic and environmental parts and it also forms the
weakest link in the genetic loop. Two other links in the model's loop deal
with the proportion of variance in intelligence and how this is due to
genetics. These other links are labeled as PMP and PIH. Since the
coefficient or magnitude of this proportion is increasing then the coefficient
is a population statistics and always depends upon the absolute value of
variance of trait factors in the environment. The paths of the two links
change with any strong change in the environmental factors. This means
that if either one of the paths from parental social status and parent's
intelligence to the child's environment increase then we would see a
decrease in the proportion of the variance in measured intelligence. The
last link to consider in the genetic loop of the polygenic model is labeled
PHP, and is highly strong. Cancro points out that a child receives half of
his or her genes from each parent. This makes the correlation between
parent-child intelligence equal to .50. Cancro warns that this correlation
is considerably larger since this figure is only subject under conditions of
random mating. This means that the closer the parents resemble one
another then the more closely children will resemble their parents (73). 
This holds true to the fact that males and females of like intelligence would
generally end up in similar settings such as school dropouts or graduate
students. These factors either limit mating or pair like individuals together
and therefore changing the previous correlation. If both parents have
above average intelligence then their children will most likely exhibit this
trait. This evidence, according to Canro, therefore is partly due to the
hereditary basis of intelligence. According to kinship correlations,
proportions of genes of intelligence that are held in common by two
relatives enable us to predict correlations between their IQs. Identical
twins, for example, posses identical genes. Vernon points out that the
interclass correlation of identical twins should be 1.0 since they share the
same genetic makeup. Heritability analysis covers the subject of twins
among other kinship relations. The correlations, according to Vernon of
genetic expectation for both dizygotic twins and non twin siblings raised
apart or together is .50. According to studies performed on these
groups, there is a high similarity between the genetically expected and the
obtained results. Vernon states that the results of his tests support the
conclusion that both genetic and environmental components have a
significant effect upon the intelligence of the child. There has also been
some research done on identical twins who live in different environments. 
They have been compared with siblings who are not twins but live in the
same environment. The correlation results for twins who live apart is .75
and .24 for no-twin siblings who do live together. It seems that together,
these two correlations almost add up to 1.00 which is the total phenotypic
variance. Vernon points out that the effect of genes is much more
powerful than that of the environment. Even though the precise values of
the correlations are of dispute, analyses of kinship data, concludes
Vernon, provides the most convincing demonstration of genetic influence
on intelligence. 
Undoubtedly ,the subject of intelligence can be defined in many ways. 
To better understand intelligence psychologist have rendered two main
influences as cause for variable intelligence levels. These two main
influences as discussed previously cannot be explained as one being the
main determinant of intelligence. This two influences are environmental
and hereditary influences.