Orval Hobart Mowrer 1960 proposed the two-process model
Classical conditioning involves learning to associate something of which we initially have no fear (neutral stimulus) with something that already triggers a fear response (unconditioned stimulus).
Operant conditioning takes place when our behaviour is reinforced (rewarded) or punished. A form of learning in which behaviour is shaped and maintained by its consequences
In operant conditioning, negative reinforcement is when the absence of unpleasant things strengthens a behaviour. Results in a desirable consequence which means the behaviour will be repeated
Operant conditioning reinforces the fear because every time someone avoids the phobic stimulus they feel calmer