Figure 7. LUM motion for a pair of pulsed L′ and M′ gratings of 1 cycle deg⁻¹ on the yellow field which produces no phase shift.

Probability correct for direction judgements of a pair of pulsed (15 ms) L′ and M′ gratings in spatial quadrature phase. Motion is near chance when two patterns are simultaneous (0 SOA). SOA is specified for the L′ pattern relative to M’.L′ contrast was 0.038 and 0.044 (C.F.S and J.D.W., respectively) and M′ was 0.071. Field luminance was 1580 Td and the wavelength was selected to yield no L’ versusM′ phase shift for each observer.