Developmental assessment at four years: are there any differences between children who do,or do not,cooperate?

Among preschool children failure to cooperate in a developmental assessment is not uncommon, but many reports do not mention this awkward situation. Can such children be ignored? The abilities of 203 children were assessed at age 4 years and 7 1/2 years. At 4 years 37 (18%) did not cooperate fully and an overall developmental score could not, therefore, be calculated. For those sections in which they did achieve a score, the mean values, in all areas of development, were lower than those of complete cooperators and the differences were significant for visuomotor function, language, and comprehension. At 7 1/2 years children in the lower social classes who had been uncooperative at age 4 years had lower scores in all six areas of ability tested than those who had cooperated fully at 4 years. No differences were found for upper class children. Refusal to cooperate may in some cases indicate inability to perform and such children should not be ignored or discarded from follow up analyses.