Which Factor Listed Below Led Pavlov to Determine That an Extinguished

Multiple Choice

Which factor listed below led Pavlov to determine that an extinguished conditioned response was not erased or forgotten, but only inhibited?

A) The unconditioned stimulus produced stronger unconditioned responses than before conditioning.
B) The conditioned response could be recovered in much less time than was originally required to learn it.
C) The conditioned stimulus always produced some diminished response after extinction.
D) Brain scans indicated that a permanent change at the synapses had occurred.