The effectiveness of tactile stimulation as a form of early intervention: a quantitative evaluation.

The results of studies examining the effectiveness of tactile stimulation as a form of sensory enrichment for infants and young children were analyzed by the use of recently developed quantitative methods that treat research synthesis as a unique type of scientific inquiry. Nineteen studies meeting certain predetermined criteria were included in the review. The 19 studies contain 103 statistical hypothesis tests that evaluated the effectiveness of tactile stimulation programs. Analysis of these tests, based on the calculation of effect sizes, revealed that subjects receiving some form of controlled tactile stimulation performed better on a variety of dependent measures than subjects not receiving intervention. Larger treatment effects were associated with pre-experimental designs, and also with studies in which the internal validity was rated as poor. Several other study characteristics, such as how the subjects were assigned to conditions and how the dependent measure was recorded, were related to study outcome as measured by effect size. The results indicate that an accurate interpretation of tactile stimulation studies cannot be made without consideration of specific design variables and study characteristics.