Hommel et al. propose that high-level perception and action planning share a common representational domain, which facilitates the control of intentional actions. On the surface, this point of view appears quite different from an alternative account that suggests that “action” and “perception” are functionally and neurologically dissociable processes. But it is difficult to reconcile these apparently different perspectives, because Hommel et al. do not clearly specify what they mean by “perception” and “action planning.” With respect to the visual control of (...) action, a distinction must be made between conscious visual perception and unconscious visuomotor processing. Hommel et al. must also distinguish between the what and how aspects of action planning, that is, planning what to do versus planning how to do it. (shrink)

Several aspects of Glover's planning–control model (PCM) appear incompatible with existing data. Moreover, there is no logical reason to suppose that separate visual representations should be required for the “planning” and “control” of actions in the first place. Although intuitively appealing, the PCM appears to lack strong empirical support.