Michael Lewis & Lawrence T. Taft 
Developmental Disabilities 
Theory, Assessment, and Intervention

The chapters in this volume are drawn from the presentations delivered at a symposium on Developmental Disabilities in the Preschool Child. This sym- posium was held under the auspices of The Institute for Pediatric Service of Johnson and Johnson Baby Products. It was co-sponsored by The College of Medicine and Dentistry of New Jersey, Rutgers Medical School, and The In- stitute for the Study of Exceptional Children, Educational Testing Service. The symposium was held in the Fall of 1979 in Chicago, Illinois and the participants, including Ph. D . 's, Ed. D . 's, and M. D . 's, represented the interdisciplinary approach which characterized the meetings. The interdisciplinary set of speakers was matched by an equally diverse audience who represented almost every profes- sional group concerned with the needs of disabled children and their families. Because of the successful information exchange that took place, a published volume of the proceedings was determined to be useful for others who were not able to attend. To all those who toil to help developmentally disabled children and their families we dedicate this volume. Michael Lewis Lawrence T. Taft vii CONTENTS Introduction xiii Part I-Sensory Development 1 / Handicapped Child – Facts of Life 3 Me"itt B. Low 2 / Theoretical Issues in the Early Development of Visual Perception 9 Joseph F. Fagan III and Patricia Ann Shepherd 3 / Clinical Appraisal of Vision 35 Richard N.