ATTENTIONAL PROCESSES ALONG A COMPOSITE STIMULUS CONTINUUM DURING FREE-OPERANT SUMMATION

Trained 5 naive adult male hooded rats on a 3-ply multiple schedule. Different variable-interval contingencies were associated with tone (T + L) and light (L + T), while simultaneous presentation of tone and light (T + L) signaled extinction (SDELTA). During compounding tests, all Ss summated to tone-plus-light absence (T + L a8), emitting more responses to this condition than to (T + L) and (L + T) conditions combined. These results establish the symmetry of the composite dimension postulated to underlie summation and indicate that the continuum extreme chosen as SDELTA determines that aspect of the composite discriminative stimulus controlling responding. They are used further to relate summation to generalization peak shift and to prove that stimulus intensity dynamism is not involved in multimodal summation. (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.