Domain specificity: modules only operate on certain kinds of inputs—they are specialised Informational encapsulation: modules need not refer to other psychological systems in order to operate Obligatory firing: modules process in a mandatory manner Fast speed: probably due to the fact that they are encapsulated (thereby needing only to consult a restricted database) and mandatory (time need not be wasted in determining whether or not to process incoming input) Shallow outputs: the output of modules is very simple Limited accessibility Characteristic ontogeny: there is a regularity of development Fixed neural architecture.