L. Poot, H. P. Snippe, and J. H. van Hateren, "Dynamics of adaptation at high luminances: Adaptation is faster after luminance decrements than after luminance increments," J. Opt. Soc. Am. A 14, 2499-2508 (1997)
As is well known, dark adaption in the human visual system is much slower than is recovery from darkness. We show that at high photopic luminances the situation is exactly opposite. First, we study detection thresholds for a small light flash, at various delays from decrement and increment steps in background luminance. Light adaptation is nearly complete within 100 ms after luminance decrements but takes much longer after luminance increments. Second, we compare sensitivity after equally visible pulses or steps in the adaptation luminance and find that flash detectability is initially the same but recovers much faster for pulses than for increment steps. This suggests that, whereas any residual threshold elevation after a step shows the incomplete luminance adaptation, the initial threshold elevation is caused by the temporal contrast of the background steps and pulses. This hypothesis is further substantiated in a third experiment, whereby we show that manipulating the contrast of a transition between luminances affects only the initial part of the threshold curve, and not later stages.
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
You do not have subscription access to this journal. Article tables are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Parameters in Eq. (4), with Test Delay Measured in Seconds, for the Three Main Observers in Experiment 1
a
Observer
γ
α
LP
HS
JH
-
Observer JH performed the increment step condition only at a single contrast thus we cannot estimate his contrast power exponent γ. The parameter for this observer is estimated with the average γ for the other two observers.
Table 2
Detectability as a Function of the Duration of a Luminance Pulse in the Adaptation Background for Two Observers
a
Observer
Duration of Background Pulse (ms)
7.5
10
20
40
500
LP
HS
The background pulse contrast, Eq. (3), was 3.5% for observer LP and 2.5% for observer HS. These contrasts were chosen to obtain approximate threshold detectability, for the 500-ms duration luminance blocks used in experiment 1.
Table 3
Test Detection Thresholds in Experiment 3 at Four Conditions for the Dynamics of the Adaptation Luminance: a Ramp Transition, a Step, a Dipole-Enhanced Step, and a Constant Luminance That Is Identical to the Luminance Reached after the Transitions in the Other Three Conditions (5600 Td)
a
Condition
Threshold (Td)
LP
HS
JH
LP
HS
JH
ramp
3220
1030 ± 60
590 ± 40
2300 ± 180
1360 ± 80
1140 ± 100
step
5600
3920 ± 240
3260 ± 160
2020 ± 160
1430 ± 90
1060 ± 100
dipole
6300
8960 ± 540
6160 ± 270
2680 ± 210
1470 ± 90
1200 ± 140
constant
5600
700 ± 50
515 ± 30
565 ± 30
Luminance before the transitions is 700 Td. Thresholds were obtained for three observers, at two delay values for the test probe: and The second column contains the luminances (in Td) of the adaptation field when the test flash is presented at delay This shows that the ordering of the thresholds for the three dynamic conditions at is preserved when thresholds are normalized relative to these background luminances. Thresholds for the constant adaptation luminance are presented in the column for Note that at this delay value the thresholds in the dynamic conditions are still considerably higher than the steady-state threshold.
Table 4
Comparison of Threshold Elevations Δ [Defined in Eq. (2)] as Measured by von Wiegand et al.8 and As Predicted from Eq. (4), Which Describes Our Step Increment Data a
τ (ms)
ratio
60
68
14.53.2
132
1.120.30
750
68
4.21.0
4.40.9
0.95 0.30
60
680
369
5012
0.72 0.25
750
680
7.62.0
175
0.45 0.20
Predicted values were derived with the average of the parameter estimates from Table 1. Measured values were estimated from Fig. 7 in the paper by von Wiegand et al.8 The data for are averaged over their two observers; data for are from their only observer at this contrast. Errors in are estimated from the experimental error bars reported in the study by von Wiegand et al.
Tables (4)
Table 1
Parameters in Eq. (4), with Test Delay Measured in Seconds, for the Three Main Observers in Experiment 1
a
Observer
γ
α
LP
HS
JH
-
Observer JH performed the increment step condition only at a single contrast thus we cannot estimate his contrast power exponent γ. The parameter for this observer is estimated with the average γ for the other two observers.
Table 2
Detectability as a Function of the Duration of a Luminance Pulse in the Adaptation Background for Two Observers
a
Observer
Duration of Background Pulse (ms)
7.5
10
20
40
500
LP
HS
The background pulse contrast, Eq. (3), was 3.5% for observer LP and 2.5% for observer HS. These contrasts were chosen to obtain approximate threshold detectability, for the 500-ms duration luminance blocks used in experiment 1.
Table 3
Test Detection Thresholds in Experiment 3 at Four Conditions for the Dynamics of the Adaptation Luminance: a Ramp Transition, a Step, a Dipole-Enhanced Step, and a Constant Luminance That Is Identical to the Luminance Reached after the Transitions in the Other Three Conditions (5600 Td)
a
Condition
Threshold (Td)
LP
HS
JH
LP
HS
JH
ramp
3220
1030 ± 60
590 ± 40
2300 ± 180
1360 ± 80
1140 ± 100
step
5600
3920 ± 240
3260 ± 160
2020 ± 160
1430 ± 90
1060 ± 100
dipole
6300
8960 ± 540
6160 ± 270
2680 ± 210
1470 ± 90
1200 ± 140
constant
5600
700 ± 50
515 ± 30
565 ± 30
Luminance before the transitions is 700 Td. Thresholds were obtained for three observers, at two delay values for the test probe: and The second column contains the luminances (in Td) of the adaptation field when the test flash is presented at delay This shows that the ordering of the thresholds for the three dynamic conditions at is preserved when thresholds are normalized relative to these background luminances. Thresholds for the constant adaptation luminance are presented in the column for Note that at this delay value the thresholds in the dynamic conditions are still considerably higher than the steady-state threshold.
Table 4
Comparison of Threshold Elevations Δ [Defined in Eq. (2)] as Measured by von Wiegand et al.8 and As Predicted from Eq. (4), Which Describes Our Step Increment Data a
τ (ms)
ratio
60
68
14.53.2
132
1.120.30
750
68
4.21.0
4.40.9
0.95 0.30
60
680
369
5012
0.72 0.25
750
680
7.62.0
175
0.45 0.20
Predicted values were derived with the average of the parameter estimates from Table 1. Measured values were estimated from Fig. 7 in the paper by von Wiegand et al.8 The data for are averaged over their two observers; data for are from their only observer at this contrast. Errors in are estimated from the experimental error bars reported in the study by von Wiegand et al.