Open peer commentary on Joel Norman's 'Two visual systems and two theories of perception: an attempt to reconcile the constructivist and ecological approaches.'
The writing of this commentary was supported by a grant from the Economic and Social Research Council (UK) ROOO239112, and from fellowships from the National Science Foundation (INT-9901349) and National Institute of Child Health and Human Development (F32 HD08568-01). We wish to thank Mark H. Johnson for helpful related discussions.