Generalized identity matching to sample of two-dimensional forms in individuals with intellectual disabilities

An assessment of identity matching to sample with two-dimensional forms was conducted with 44 subjects with moderate and severe intellectual disabilities. Identity matching that did not require conditional discriminative functions was tested first; subjects who passed that test were then tested on a conditional identity matching task. Tests for generalized identity matching were passed by 30 of the 44 subjects. The 14 individuals who did not pass were given a further teaching assessment that sought to teach identity matching directly via standard teaching methods. Some subjects also received training on a series of simple discriminations taught by the same methods. Four additional subjects passed identity matching tests. Overall, generalized identity matching was demonstrated in 34 of 44 subjects, including 7 of 16 individuals with mental age (MA) scores of 3.0 years and below and 14 of 15 individuals with MA scores between 3.0 and 5.0 years. Results with these two groups are much superior to those typically reported for individuals with comparable MA scores. The capacity for generalized performances requiring same/different judgments appears to have been substantially underestimated in this population, perhaps especially when the stimuli are two-dimensional, relatively abstract forms.