Each panel plots the normalized recovery of

*a*_{max} for a different subject at a range of bleaches; the subjects were the same as in . In all cases the curves plot , obtained by substitution of into ; the parameter

*c*_{a} in is then equal to

*I*_{equiv}(0)/

*I*_{0}, where

*I*_{equiv}(0) is the initial magnitude of the equivalent background intensity and

*I*_{0} is the half-saturating intensity for steady backgrounds. For the three observers, we had previously obtained

*I*_{0}= 80, 42 and 48 Td for panels

*A, B* and

*C*, respectively (see ).

*A*, recovery for subject FD, determined in two sessions following bleaches estimated as 16, 47 and 100 %. In panel

*A* dim flashes were also presented during recovery, and

*a*_{max} was determined using the first approach (iterative fitting).

*B*, recovery for subject TDL, following bleaches estimated as 8, 15, 47 and 91 %, and two bleaches of 100 %.

*C*, recovery for subject MMT, following bleaches estimated as 8, 15, 46, 69 and 100 %. In panels

*B* and

*C* the results were analysed using the second approach (measurement at fixed time). Symbols, bleach levels and parameters of the curves for the three subjects were:

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