Stimulus for each task. a) Motion coherence task, for which a proportion of the dots moved coherently (3 – 67%), and subjects discriminated the direction of these coherent dots (upward vs. downward). b) Fine direction-of-motion task, for which 67% of the dots moved coherently, and subjects discriminated their direction (tilted leftward vs. rightward of downward motion). c) Orientation task, for which a static 1% contrast sinusoidal grating was presented and subjects discriminated its orientation (tilted slightly to the left or right of vertical).