Investigations of Visual Perception Abilities in Individuals with Severe Intellectual Disabilities
This project a five-year study of visual perceptual skills in individuals who have severe intellectual disabilities. The goal is to determine the extent to which difficulties in perception affect discrimination learning. Previous research has resulted in an effective, integrated set of methods for assessing and teaching same/different judgments with difficult-to-teach populations. Stimuli used thus far have been forms which differed along several dimensions. In the current project, we ask whether participants are capable of discriminating stimuli that are more similar to one another (i.e., that differ along fewer dimensions). The ability to make such discriminations is essential if participants are to respond differentially to abstract stimuli such as printed letters (e.g., m vs. n) or numbers (e.g., 3 vs. 8). To make these relatively fine discriminations, the defining stimulus differences must be detected (perceived). Until recently, however, the methodological foundation for profiling the perceptual abilities of individuals with severe disabilities did not exist. Recent work has established this potential. In overview, our plan is to elaborate and extend procedures we have developed in order to conduct the first truly comprehensive assessment of visual perception in individuals with severe retardation and limited language skills. The Specific Aims of the project are to: (1) Establish the validity of new methods that will be used to assess visual perception in individuals with severe mental retardation; (2) assess participants' psychophysical thresholds along a number of fundamental dimensions critical in detection of form stimuli; and (3) use the perceptual profiles to both predict and remediate problems in discriminating stimuli that are physically similar.