Many students of cognitive development go even further, attributing to object play a crucial role in the growth of thought and understanding.

Piaget argued that cognitive development progresses through sequential stages as clear as the stages of physical development, and that object play helps children move through these stages. It is through interactions with objects that mental schemas such as space, time, number, and conservation of matter become refined. As Piaget says, "To think, for example, is to classify, to arrange, to place in correspondence, to collect, to dissociate, etc. But all these operations must be carried out materially in actions, in order to be capable afterward of being constructed in thought."

In a pioneering investigation, Elardo, Bradley, and Caldwell studied 77 infants using an inventory of home stimulation variables. They were looking for aspects of the home environment that correlate with Stanford-Binet IQ at 36 months. Three variables, measured at 6 months and at 12 months, correlated with later IQ. They were "provision of appropriate play materials," "maternal involvement with child," and "organization of physical and temporal environment."

Gottfried reviewed a series of longitudinal studies designed to identify home environment variables that correlate with cognitive development. The two most potent variables correlating with cognitive development during infancy and the preschool years were the availability of play materials and the quality of maternal (parental) involvement. With advancing age, the relationships between play materials and parental involvement were found to influence cognitive development even more.

The toys that correlated with intellectual function were those that fit the interests and abilities of the children studied. They are referred to as "age appropriate," "responsive," and "providing feedback when manipulated."

If the competencies children have are influenced by the quality, character, and timing of their early experiences, then we should know more than we do about how objects influence those experiences.

During the 1970s and early 1980s, the Johnson & Johnson Baby Products Company supported a major research program on the design of toys for infants. The author served as Director of Research for this program. The Johnson & Johnson research demonstrated that physical features of toys powerfully influence play duration and the range of experiences an infant can have while playing.

Through fifteen years of observations, we came to appreciate the many ways objects contribute to growth and development. The main ones are listed in Table 1. We learned that toys should meet the performance criteria listed in Table 2 if they are to be optimally useful for infants.

If an object is too simple, too complex, or otherwise unappealing, then exploratory behaviors are not sustained. Without sustained exploration, mastery cannot be achieved, and the self-confidence and receptivity to sharing that accompany mastery remain elusive.

Studies of infants from 12-33 months show that interactions with the physical environment can account for approximately 80-90% of waking time. K. Allison Clarke-Stewart found that a group of 9- to 18-month-old infants spent 46% of their waking time looking at and playing with physical objects, compared with 36% interacting with mother.

In addition to the amount of time that infants devote to exploration of the physical environment, investigators have been impressed by the seriousness with which infants conduct their explorations (Figures 1 and 2).

The first two years of life, during which exploration of the physical environment occupies so much of the infant's time, is also a period of rapid brain growth. New research methods are now propelling efforts to correlate spurts in brain development with spurts in cognitive abilities.

By adding more parts, and using flexible materials, we greatly expanded the number of ways the object could be explored, and the visual, tactile, and auditory consequences of these explorations. Now it can be twisted, bent, and stretched; examined by one hand alone, or by two together. And exploration with the mouth can be added without interrupting exploration with eyes and hands. Any change in handling alters the configuration of the object and invites additional exploration (Figure 3).

Between 6 and 9 months, the two hands begin to operate with increasing independence, finally allowing each hand to hold a separate object at the same time. The infant looks quizzically back and forth between the two hands, first staring at the object in one, then the object in the other, and so on, back and forth. The two objects are then brought close together. Finally, they are allowed to touch. A sound results. They are then brought together more forcefully, and louder sounds result. These discoveries can generate great excitement and pleasure (Figure 5).

It is exciting to watch this steady growth in the complexity of exploratory maneuvers. But, we are only seeing the tip of the iceberg. For a mind is also being stimulated to grow. The cautious exploration of how objects can be brought together and touched might occasion the birth of the idea: "more than one." This might, in turn, be a threshold event for the cognitive exploration of classification, sets, series, systems, and so on.

As the potentials for the use of multi-part objects become clearer, fitting relationships move to center stage. Now there is great interest in putting smaller objects inside larger ones, such as small blacks into a cup.

The exploration of physical relationships unfolds in an orderly manner. After the ideas of "more than one" and "inside/outside" become clear, infants use all the opportunities we give them to put smaller things inside larger things. We designed the Johnson & Johnson BALLS IN A BOWL toy to encourage such explorations (Figure 6). The three small, transparent balls fit easily through the mouth of the translucent container. The spinners inside the small balls add interest because they are decorated with bold graphics, and they spin easily, even when they are inside of the large ball.

From 9 to 36 months, children continue to explore physical relationships in multi-part toys. These toys need to provide increasing challenge to keep up with the expanding interests and skills. The Johnson & Johnson FITTING FORMS toy was designed to be more challenging than BALLS IN A BOWL. The fits are more demanding, and the differences in shape are now introduced (Figure 7).

On it goes--growing skills of action and understanding produce increasing competence in dealing with the world, and this new competence propels the growth of self-confidence needed to maintain momentum in all aspects of development.

In addition, an infant needs a safe, stimulating, physical environment that offers a wide range of materials to explore. She needs objects that capture her visual and aural attention, respond easily to her ways of exploring them, offer her opportunities to rehearse emerging skills, and invite experimentation and innovation.

Behavioral research has confirmed that in the early years of life children spend most of their waking time exploring objects. This is also a time of rapid brain growth, and theories of brain development suggest that the structure of early experience influences brain development, including the shaping of functional neuronal circuits.

A picture begins to emerge from these facts. We can now see how play with objects in the early years of life helps to build a foundation of skills needed for subsequent development.

by Richard Allen Chase, MD
Adjunct Professor of Psychiatry and Behavioral Sciences,
The Johns Hopkins University School of Medicine, and
Chief Executive Officer, Learning Pathways, Inc.

Photographs by Bill Parsons

This article first appeared in The Journal of Perinatal Education (Volume 3, Number 2, 1994).