Acquisition of American Sign Language versus Amerind signs in a mentally handicapped sample

The differential acquisition of American Sign Language versus Amerind signs was investigated in a moderately to severely mentally handicapped sample. The subjects (n = 10) were selected from a residential training facility and each had a mental age within the range 3;0-5;0 years. Twenty signs were taught to each subject, 10 American Sign Language signs and 10 Amerind signs. An Alternating Treatments Design was selected to facilitate comparison of the relative efficacy of the two sign systems across single subjects. Five signs were presented per week (2 weeks) in each sign system. Results showed that a significantly greater (p less than .001) number of Amerind as compared to American Sign Language signs were acquired during Week 1, Week 2, and across both weeks. Retention results, after 1- and 2-week delays, showed that subjects continued to reproduce significantly more Amerind than American Sign Language signs. The results were thought to be due to the more concrete and less complex nature of the Amerind system. Implications of these results for this and similar samples are discussed.