The "psychic secretions" that interfered with Pavlov's experiments on digestion were:
Aprimary reinforcers.
Bconditioned responses.
Cconditioned stimuli.
Dsecondary reinforcers.
Eunconditioned responses.
Aprimary reinforcers.
Bconditioned responses.
Cconditioned stimuli.
Dsecondary reinforcers.
Eunconditioned responses.