Stimulus and communication demands of visual acuity tests.

Comparative evaluations of visual acuity tests designed for young children have been difficult because tests vary both by stimulus target and by response methods required to communicate what is seen. To determine the independent effect of stimulus targets and response methods, four methods of response were systematically varied across four types of visual acuity tests and given to 59 preschool and early primary school children at three distances. An analysis of variance revealed that tests in which the stimulus target included a directional component were more difficult than those which did not, and that verbal report was the easiest method of answering; pointing to a picture on a key card which matched a target stimulus was the most difficult. Results are discussed in terms of developmental theory.