Studien �ber den stereoskopischen Glanz

A simple model of binocular luster

“…Our current model is based on the assumption that monocular contrast signals from the two eyes interact in some way at an early binocular stage. Instead of being integrated into a stable binocular contrast signal, two incompatible monocular signals seem to remain in a state of competition, which many researchers believe to be the cause for a lustrous sensation (e.g., Brewster, 1861 ; Howard, 1995 ; Sachsenweger, 1960 ; Sachsenweger, 1961 ; Wendt & Faul, 2022 ). This may be due to a binocular mechanism that is unable to combine the conflicting monocular signals.…”

“…No time constraints were imposed on the subjects for the two tasks. They were also asked to move their eyes over the stimuli during presentation, as it was found that fixation of the target area can lead to a weakening of the lustrous effect due to local adaptation ( Kiesow, 1920 ; Sachsenweger, 1960 ; Wendt & Faul, 2022 ). For the entire experimental series, the subjects needed between 20 and 25 hours, divided into 10 to 12 blocks of about 2 hours each.…”

“… Anstis (2000) assumed that the lustrous effect results from the inability of the visual system to binocularly combine the two discrepant monocular contrast signals: At the retina, incremental and decremental luminance patterns are encoded by two different types of ganglion cells, which are referred to as ON- and OFF-center cells, respectively (see also the model description in the following section). A dichpotic inc–dec stimulus would trigger these two cell types at corresponding retinal positions whose signals, however, cannot be integrated at a binocular level and therefore remain in a state of conflict, causing a sensation of luster ( Burr, Ross, & Morrone, 1986 ; Sachsenweger, 1960 ).…”

Binocular luster elicited by isoluminant chromatic stimuli relies on mechanisms similar to those in the achromatic case

“…According to Anstis (2000) , the visual system is unable to integrate these two monocular signals at a binocular level, and they therefore remain in a state of competition, causing the phenomenon of luster (similar conflict ideas have already been proposed by Brewster, 1861 , and Sachsenweger, 1960 ; see also Mausfeld, Wendt, & Golz, 2014 ; Wendt & Faul, 2022b ). Alternatively, there may be binocular cells in the early visual system that specifically respond to interocular conflicts, particularly to between-eye luminance patterns with reversed contrast polarities ( Kingdom, Read, Hibbard, & May, 2022 ); we discuss this idea in more detail in the General Discussion section.…”

“…Because binocular luster is generally a rather unstable phenomenon for which the perceived strength tends to vary over time (cf. Qiu, Caldwell, You, & Mendola, 2020 ; Ruete, 1860 ; Sachsenweger, 1960 ; Wendt & Faul, 2022b ), subjects were asked to base their judgment on the maximum perceived luster during the stimulus presentation (the duration of which was not time limited). It should be noted that this instability is especially pronounced for stimuli without a ring or with larger ring widths, whereas thin rings seem to have a stabilizing effect on the lustrous sensation ( Wendt & Faul, 2020 ; Wendt & Faul, 2022b ).…”