A critical discussion is provided of three central assumptions underlying Nunez's approach to modeling cortical activity. A plea is made for neurophysiologically realistic models involving nonlinearities, multiple time scales, and stochasticity.

The epistemological premises and scientific viability of Stoffregen & Bardy's ecological perspective are evaluated by analyzing the concept of direct perception of global invariants vis-à-vis (1) behavioral evidence that perception is based on the integration of modal sources of information and (2) neurophysiological aspects of the integration of sensory signals.