Acquisition and generalization of simple manual sign grammars by aphasic subjects

The present study investigated the acquisition and generalization of manual sign combinations in four moderately to severely aphasic subjects. Two experiments were conducted: In the first, matrices were employed to train agent-action-object and action-object combinations and monitor generalization. In the second experiment, subjects were trained to combine a different set of single signs into sign combinations (agent-action-object, action-object) that could be used to describe two pictures while generalization was monitored in a third. Results of experiment 1 demonstrated that the two least severely aphasic subjects were able to acquire and generalize all of the sign combinations presented in the training matrices. In the second experiment, although the subjects rapidly acquired single signs and combinations, additional training was required for the subjects to produce the sign combinations to describe the two pictures and no generalization was noted in the third untrained picture. It is concluded that success in manual sign training programs is related to severity of aphasia; that aphasic subjects' propositional use of manual signs rarely follows simple acquisition; and that generalization to untrained stimuli or environments does not occur without additional training.