Early experiences seem to be important in providing the background necessary to cope with the environment at a later age. The parents who are proud of the “good baby” lying quietly in the crib may not be giving that baby what is best for him. The importance of a stimulating environment in the early years can be further illustrated by a classic study by Skeels and Dye (1939).

A group of orphaned children (whose development at the age of nineteen months was so retarded that adoption was out of the question) was transferred to an institution for the mentally retarded. In this institution, in contrast to the overcrowded orphanage, each child was placed in the care of an older, mildly retarded girl who served as a surrogate mother, spending great amounts of time playing with the child, talking to him, and informally training him.

In addition, the living quarters were spacious and well equipped with toys. As soon as the children could walk, they began to attend a nursery school where additional play materials and stimulation were provided. After a period of four years, this experimental group showed an average gain in intelligence of 32 I.Q. points; a control group that remained in the orphanage showed a loss of 21 points. A follow-up study over 20 years later found the experimental group to be still superior to the control group (Skeels, 1966). Most of the experimental group had completed high school (one-third had gone to college), were self-supporting, and had married and produced children of normal intelligence. Most of the control group, on the other hand, had not progressed beyond third grade and either remained institutionalized or did not earn enough to be self supporting.

Although the number of subjects in this study was small and the possibility of some innate intellectual differences between the experimental and control groups cannot be completely ruled out, the results are sufficiently impressive to indicate the importance of stimulating early environment for later intellectual development.


Stages in Development

As a developmental concept, a stage usually defines a set of behaviours that occur together. As a group, they characterize a quality of behaviour that differs appreciably from the quality of behaviour in earlier and later stages. Stages follow each other in an orderly sequence, and the transition from one stag to the next usually involves a process of integration, whereby the behaviour from the earlier stage is transformed into the next, along with some new elements. While environmental factors may speed up or slow down development, they do not change its sequence.

Cognitive Development

Stage 1. Sensor motor (Birth-2 years): Infant differentiates himself from objects; gradually becomes aware of the relationship between his actions and their effects on the environment so that he can act intentionally and make interesting events last longer (if he shakes a rattle it will make a noise); learns that objects continue to exist even though no longer visible (object permanence).


Stage 2. Preoperational (Birth 2-7 years): Uses language and can represent objects by images and words; is still egocentric, the world revolves around him and he has difficulty taking the viewpoint of others; classifies objects by single salient features: If A is like B in one respect, must be like B in other respects; toward the end of this stage begins to use numbers and develop conservation concepts.

Stage 3. Concrete Operational (7-12 years): Becomes capable of logical thought; achieves conservation concepts in this order: number (age 6), mass (age 7), weight (age 9): can classify objects, order them in series along a dimension (such as size), and understand relational terms (A is longer than B).

Stage 4. Formal Operational (12 and up): Can think in abstract terms, follow logical propositions, and reason by hypothesis; isolates the elements of a problem and systematically explores all possible solution; becomes concerned with the hypothetical, the future, and ideological problems.