An ERP study of stimulus equivalence in aphasic and non-brain damaged individuals

Susanne Rasmussen, University of Texas at El Paso


In this study, one aphasic and four non-brain damaged adults engaged in a computerized equivalence-training procedure while cortical activation was recorded using event-related potentials (ERP). Equivalence training is a procedure used to promote transfer and generalization of learned skills. It is described by the properties reflexivity (A = A), discrimination (A = B), symmetry (if A = B then B = A), transitivity (if A = B and B = C then A = C), and equivalence (C = A). ERP is a non-invasive imaging procedure that records cortical activation in response to time or response specific events. The task consisted of a matching-to-sample paradigm of nonsense symbols. The symbols were presented at increasing complexity. Participants were required to touch a sample and then a matching choice on a computer monitor for a total of 201 trials. The present study compared the performance of the non-brain damaged individuals to the brain-damaged individual. The results show that both the aphasic and non-brain damaged individuals learned the equivalence relationships. The aphasic exhibited longer physical response latencies and cognitive latencies different from the non-brain damaged individuals. Additionally, cortical activation in the aphasic was marked by areas of high activation contrasted by areas of inactivation. This pattern was not observed in the non-brain damaged individuals. The implication of the study is that the aphasic processed stimuli different from non-brain damaged individuals and required added processing time, but he learned and generalized the emblematic relationships.

Subject Area

Speech therapy

Recommended Citation

Rasmussen, Susanne, "An ERP study of stimulus equivalence in aphasic and non-brain damaged individuals" (2005). ETD Collection for University of Texas, El Paso. AAI1430965.