Hebb's Theory Of Intelligence

Hebb thought of a theory which attempted to acknowledge the influence of both genetics and environmental influences on child intelligence; the notion Intelligence A and Intelligence B.
Intelligence A is regarding the individual's potential attainable intelligence inherited through their genes. Intelligence B is how far this genetic potential can reach as a result of the child's experience in their environment. Vernon added Intelligence C to these, which takes into account that intelligence tests only measure a part of someone's intelligence B, so intelligence C is the unknown amount of intelligence which is measured in an IQ test.
Some theoriests have much more extreme theories, eg. An extreme nativist point of view is that absolutely all intelligence

With an adopted child, we would need to compare the similarity between the child and their birth parents – with whom the child shares genes but not environment, and compare this to the child and their adoptive parents. If the child is more similar in their intelligence, behaviour and skills to its birth parents than adoptive parents, this would demonstrate the influence of heredity.
In a study called the Texas Adoption Project (Loehlin, Horn and Willerman, 1994) adopted children were given IQ tests around the age of 18. Their scores were correlated against the scores of their birth mothers and of both their adoptive parents. The children's IQ's were somewhat predicted by their natural mothers' IQ's but not by their adoptive parents IQ's, even though they had spent their entire childhoods with the latter. This shows, like the twin studies of IQ, that there is a substantial genetic component in what is measured in IQ testing.
Cyril Burt conducted the most significant twin studies. His results showed that intelligence is indeed inherited. His results brought about the 11+ system in the UK as intelligence was seen to

It certainly does seem that intelligence is influenced by the environment a child is raised in. If we accept this idea, then we can accept that it is possible to improve a child's intelligence by improving their environment. There are many studies that document how a higher IQ can be achieved when children are moved from a deprived environment into a more enriched and stimulating one. Mason
(1942) reported about a child who had been raised by a mute mother in a dark attic up to the age of
6 and a half. When discovered she was retarded and without any speech. However, on moving her to a residency where she received extensive treatment she recovered to a remarkable extent, and acquired speech, a normal intellectual level and good social functioning.
Skeels (1966) studied 25 nineteen month old orphans. Thirteen of them had IQs of about 60 and these were considered unadoptable. These children were moved out of their over-crowded home to a special institution where they were taken care of by older sub-normal girls, who acted as substitute mothers. These orphans were now given a great deal of one-to-one attention and