Deficit model This model sees learning difficulties as being mainly due to deficits or internal factors within the pupil rather than to external factors. Learning difficulties from this perspective are caused by factors such as sensory impairment, low ability, medical conditions, emotional and behavioural problems and specific information processing problems. External factors are seen as less important or as insignificant. External factors include poor teaching, inappropriate curriculum and poor school attendance. An interactionist model or perspective sees learning difficulties as being due to an interaction between both internal and external factors.