Weakness - two-process model can't explain cognitive characteristics of phobias
people with phobias have irritational beliefs regarding the phobic item/situation
sufferers of claustrophobia may think 'I'm going to be trapped in this lift and suffocate', which is an irrational thought and not taken into consideration in behaviourist explanation.
behaviourist approach only focuses on observable behaviour, it's unable to account for these cognitive symptoms and not a complete explanation of phobias.