Table 1. Theoretical time (ms) to reach detection threshold.

	Stimulus condition
Stimulus intensity	Luminance	S-cone increment	S-cone decrement
2 × threshold	137	247	303
4 × threshold	93.3	180	227
8 × threshold	73.3	143	183
12 × threshold	63.3	127	163

Stimulus temporal profile was assumed to be 190 ms sinusoidal increment, 190 ms constant in the maximum modulation and 190 ms sinusoidal decrement, as in McKeefry et al. (2003). Impulse response functions in Fig. 4 were used and the temporal step size in this calculation was 3.33 ms. Zero time is defined as the stimulus onset (no delay, reaction latency or time for motor response is included).