stimulus luminance
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2022 ◽  
Vol 18 (1) ◽  
pp. e1009738
Author(s):  
William Turner ◽  
Daniel Feuerriegel ◽  
Robert Hester ◽  
Stefan Bode

We often need to rapidly change our mind about perceptual decisions in order to account for new information and correct mistakes. One fundamental, unresolved question is whether information processed prior to a decision being made (‘pre-decisional information’) has any influence on the likelihood and speed with which that decision is reversed. We investigated this using a luminance discrimination task in which participants indicated which of two flickering greyscale squares was brightest. Following an initial decision, the stimuli briefly remained on screen, and participants could change their response. Using psychophysical reverse correlation, we examined how moment-to-moment fluctuations in stimulus luminance affected participants’ decisions. This revealed that the strength of even the very earliest (pre-decisional) evidence was associated with the likelihood and speed of later changes of mind. To account for this effect, we propose an extended diffusion model in which an initial ‘snapshot’ of sensory information biases ongoing evidence accumulation.


Author(s):  
Kallene Summer Vidal ◽  
Avinash J. Aher ◽  
Dora Fix Ventura ◽  
Jan Kremers

Abstract Purpose To study the spatial retinal distribution of electroretinographic (ERG) responses that reflect signals in the L-/M-cone-opponent and luminance post-receptoral pathways. Methods ERG recordings to heterochromatic stimuli (sinusoidal counter-phase modulation of red and green LED light sources) were performed, while varying fractions of red and green modulation. Two temporal frequencies of the stimuli were employed: 12 Hz to record ERGs that reflect L-/M-cone-opponent signal and 36 Hz for recording ERG signals sensitive to stimulus luminance. Stimuli were about 20° in diameter and projected on various retinal locations: the fovea and four eccentricities (10°, 19°, 28° and 35°), each presented nasally, temporally, inferiorly and superiorly from the fovea. Results The 36 Hz stimuli elicited responses that strongly varied with red fraction and were minimal at iso-luminance. Moreover, response phases changed abruptly at the minimum by 180°. In contrast, the responses to the 12 Hz stimuli had amplitudes and phases that changed more gradually with red fraction. The 36 Hz response amplitudes were maximal close to the fovea and sharply decreased with increasing distance from the fovea. The responses to 12 Hz stimuli were more broadly distributed across the retina. Conclusions In the present study, it was found that retinal eccentricity and direction from the fovea have distinct effects on ERGs reflecting different post-receptoral mechanisms. The results are in accord with previous findings that ERGs to 12 Hz stimuli are predominantly determined by the red–green chromatic content of the stimuli, thus reflecting activation in the L-/M-cone-opponent pathway, while responses to 36 Hz stimuli manifest post-receptoral luminance-dependent activation. We found that the response in the cone-opponent pathway is broadly comparable across the retina; in comparison, response amplitude of the luminance pathway strongly depends on retinal stimulus position.


Author(s):  
Fu Jiang ◽  
Mark D. Fairchild

The human visual system is capable of adapting across a very wide dynamic range of luminance levels; values up to 14 log units have been reported. However, when the bright and dark areas of a scene are presented simultaneously to an observer, the bright stimulus produces significant glare in the visual system and prevents full adaptation to the dark areas, impairing the visual capability to discriminate details in the dark areas and limiting simultaneous dynamic range. Therefore, this simultaneous dynamic range will be much smaller, due to such impairment, than the successive dynamic range measurement across various levels of steady-state adaptation. Previous indirect derivations of simultaneous dynamic range have suggested between 2 and 3.5 log units. Most recently, Kunkel and Reinhard reported a value of 3.7 log units as an estimation of simultaneous dynamic range, but it was not measured directly. In this study, simultaneous dynamic range was measured directly through a psychophysical experiment. It was found that the simultaneous dynamic range is a bright-stimulus-luminance dependent value. A maximum simultaneous dynamic range was found to be approximately 3.3 log units. Based on the experimental data, a descriptive log-linear model and a nonlinear model were proposed to predict the simultaneous dynamic range as a function of stimulus size with bright-stimulus luminance-level dependent parameters. Furthermore, the effect of spatial frequency in the adapting pattern on the simultaneous dynamic range was explored. A log parabola function, representing a traditional Contrast Sensitivity Function (CSF), fitted the simultaneous dynamic range data well.


2020 ◽  
Author(s):  
William Turner ◽  
Daniel Feuerriegel ◽  
Robert Hester ◽  
Stefan Bode

AbstractWe often need to rapidly change our mind about perceptual decisions in order to account for new information and correct mistakes. One fundamental, unresolved question is whether information processed prior to a decision being made (‘pre-decisional information’) has any influence on the likelihood and speed with which that decision is reversed. We investigated this using a luminance discrimination task in which participants indicated which of two flickering greyscale squares was brightest. Following an initial decision, the stimuli briefly remained on screen, and participants could change their response. Using psychophysical reverse correlation, we examined how moment-to-moment fluctuations in stimulus luminance affected participants’ decisions. This revealed that the strength of even the very earliest (pre-decisional) evidence was associated with the likelihood and speed of later changes of mind. To account for this effect, we propose an extended diffusion model in which an initial ‘snapshot’ of sensory information biases ongoing evidence accumulation.


2020 ◽  
Author(s):  
William Turner ◽  
Daniel Feuerriegel ◽  
Robert Hester ◽  
Stefan Bode

We often need to rapidly change our mind about perceptual decisions in order to account for new information and correct mistakes. One fundamental, unresolved question is whether information processed prior to a decision being made (‘pre-decisional information’) has any influence on the likelihood and speed with which that decision is reversed. We investigated this using a luminance discrimination task in which participants indicated which of two flickering greyscale squares was brightest. Following an initial decision, the stimuli briefly remained on screen, and participants could change their response. Using psychophysical reverse correlation, we examined how moment-to-moment fluctuations in stimulus luminance affected participants’ decisions. This revealed that the strength of even the very earliest (pre-decisional) evidence was associated with the likelihood and speed of later changes of mind. To account for this effect, we propose an extended diffusion model in which an initial ‘snapshot’ of sensory information biases ongoing evidence accumulation.


2018 ◽  
Vol 2018 (1) ◽  
pp. 308-312 ◽  
Author(s):  
Minchen Wei ◽  
Siyuan Chen ◽  
Ming Ronnier Luo
Keyword(s):  

2009 ◽  
Vol 49 (23) ◽  
pp. 2747-2753 ◽  
Author(s):  
Nick Gover ◽  
John R. Jarvis ◽  
Siobhan M. Abeyesinghe ◽  
Christopher M. Wathes

2008 ◽  
Vol 8 (1) ◽  
pp. 15 ◽  
Author(s):  
Katharina Georg ◽  
Fred H. Hamker ◽  
Markus Lappe

2007 ◽  
Vol 17 (4) ◽  
pp. 538-544 ◽  
Author(s):  
M. Gonzalez De La Rosa ◽  
M. Gonzalez-Hernandez ◽  
V. Lozano Lopez ◽  
D. Perera Sanz

Purpose Stimulus luminance (L) and area (A) are related by the equation LxAk=constant. The authors evaluated the k value at 66 positions of the central visual field in patients with glaucoma, to modify L and A simultaneously in order to examine advanced glaucomas with a bigger dynamic range. Methods The luminance limitation of a computer screen with automatic photometric control was compensated for by increasing the stimulus area in the range between 0 and 17 dB, using the k topographic values previously calculated on normal subjects. Four initial series of 21, 12, 10, and 10 glaucomas were sequentially examined with the Octopus 311 in which the stimulus size cannot be freely changed during the examination, and with the experimental method (Pulsar-SAP) modifying stimulus sizes to equal the results. k Final estimation was verified in 60 new cases. Results k Values increase progressively with defect deepness. Values higher than those of the normal population with equivalent topographic differences were obtained. Correlation between indices was as follows: MD: r=0.94 (p<0.0001); square root of the loss of variance (sLV): r=0.93 (p<0.0001). Frequency of local defects was similar in both procedures. Average topographic differences between thresholds were usually less than 1 dB. The average threshold difference favored Pulsar-SAP by 0.45 dB at those points where the average threshold of both examinations was less than 18 dB and 0.37 dB where such average was higher than or equal to 18 dB. Conclusions k Value is higher in patients with glaucoma than in normal subjects, although the topographic features are similar. It is feasible to design a scale combining stimulus luminance and sizes to use screens with relative low brightness as surfaces for visual field examination.


2001 ◽  
Vol 41 (16) ◽  
pp. 2157-2164 ◽  
Author(s):  
Ulrich Schiefer ◽  
Hans Strasburger ◽  
Stephan T. Becker ◽  
Reinhard Vonthein ◽  
Jan Schiller ◽  
...  

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