Early psychologists argued that there were critical periods for learning and development - that is, if a child did not accomplish the developmental benchmark of a stage of development by a certain age, then the child's development was "arrested." This idea was even part of Freud's original psychosexual development; if children were not able to resolve a conflict by a certain age, then they were fixated, leading to certain behaviours and personality traits.

Psychologists were particularly interested in the development of language and IQ.  Early studies, such as the study of Genie or the feral boy Victor of Aveyron, led researchers to think that if language were not learned by a certain age, then it would not be possible to develop it in the future.  The study below will show why using a single case study - for example, the case of Genie - may lead researchers to draw false conclusions when they attempt to generalize to a wider population.

Koluchova (1972) carried out a longitudinal study of a pair of Czech monozygotic twin boys who had been discovered at the age of 7 in terrible living conditions.

The boys’ mother had died when they were born; they were raised by their father and then later, after the father remarried, their step-mother.  The step-mother kept them in conditions of severe deprivation. They lived in a small, unheated closet and were often locked for long periods in the cellar. They had been mistreated and beaten. They did not have adequate food, so they were suffering from vitamin deficiency when they were found. They had no access to exercise or stimulation of any kind, apart from the contact they had with each other.

Apparently, nobody knew of their existence. But by the time they reached age seven, their situation came to the attention of the authorities. At that time, the boys could hardly walk, play, or speak. They were initially placed in foster care and then later adopted by two sisters.

When they were found, the twins’ prognosis seemed very poor.  When the boys were first put into kindergarten, they would not play with the other children.  They were very timid and mistrustful. They were brought to kindergarten in a wheelchair because they could not walk.

The boys' speech was also very poor. They used gestures to communicate with each other and could only repeat two or three words at a time with poor pronuciation. They could not answer questions.

In order to carry out the study, Koluchova carried out a series of observations of their free play. This started with the boys often being afraid of objects that she would give them (e.g. moving mechanical toys).  Because of their low level of development, it was not possible in the beginning to carry out regular psychological testing.  She found that the boys could not understand the meaning or function of pictures.  This is a standard way to evaluate a child's level of vocabulary.  The researchers had to use pictures that were the same size as the object they represented - and eventually, a symbolic understanding developed.

The boys were able to complete the Wechsler Intelligence Test (WISC) at the age of 8 years and 4 months. It is estimated that their IQ scores were around 40 when they were found.  The chart below shows their development over the following three years.

Their school performance was generally good and they were highly motivated. By the age of fourteen they had caught up academically to other 14-year-olds, and as adults, they were able to attend university and develop good relationships with others.

It seems that, given the right sort of loving and caring environment and the opportunity to develop an attachment to a sensitive caregiver, the effects of deprivation may be reversible.

There are some important considerations when drawing conclusions about a child's ability to overcome adversity.

1. The twins were not totally isolated, so they may have formed an attachment to each other. This may account for their ability to later form healthy relationships with others.
2. The twins were discovered at the age of 7 which may explain why they recovered from the effects of their abuse; similar children who were discovered much later in life did not always demonstrate such a high level of resilience.
3. Because we do not have any way of knowing the academic potential of the children prior to the abuse, we cannot say for sure how well they have recovered.
4. This is a case study of two individuals, so the findings may not be easily generalized - gender, culture and historical period must be considered.