Behaviorists tried to replace the mind with reflexes which Fodor describes as encapsulated (cognitively impenetrable or unaffected by other cognitive domains) and non-inferential (straight pathways with no information added). Low level processes are unlike reflexes in that they are inferential. This can be demonstrated by poverty of the stimulus arguments in which the proximate stimulus, that which is initially received by the brain (such as the 2D image received by the retina), cannot account for the resulting output (for example, our 3D perception of the world), thus necessitating some form of computation.