1.
Science
; 177(4053): 1009-11, 1972 Sep 15.
Artigo
em Inglês
| MEDLINE
| ID: mdl-17788815
RESUMO
When presentation of a retractable lever always preceded food delivery, rats licked or gnawed the lever. They also approached but seldom orally contacted a lever signaling brain-stimulation reinforcement; instead, subjects sniffed, pawed, or "explored" the lever. Therefore, a Pavlovian conditioned stimulus evoked directed skeletal responses whose specific form depended on the forthcoming unconditioned stimulus.