Response to Maniatis’ “Is a unified model of contrast and constancy possible? Reply to Gilchrist”

1. Maniatis claims that a unified explanation of lightness contrast and lightness constancy is not possible. But there is only one visual system and it exhibits both lightness contrast and lightness constancy. So obviously a unified theory is possible. 2. Maniatis claims there is ultimately no distinction between framework and layer theories, arguing that both theories acknowledge the existence of both layers and frameworks. But these theories make different predictions and those predictions can be tested.