Washington, Dec 3 (ANI): Scientists have tried to understand how the eyes and the brain make sense of what we see as the visual system constantly takes in ambiguous stimuli, weighs its options, and decides what it perceives.
According to researchers at California Institute of Technology, the visual process normally happens effortlessly, but at times an ambiguity is persistent, and the visual system waffles on which perception is right.
Most scientists believe that rivalry occurs only when there's "spatial conflict", when two objects striking the same place on the retina at the same time as our eyes move.
However, the retina isn't the only filter or organizer of visual information. There's also the "non-retinal reference frame", objects such as mountains or chairs that locate things in space and make the world appear stable even when our eyes are moving.
"We asked: what if visual ambiguities are not presented on the same spot on the retina, but on the objects in the frame as they move around," Jeroen J.A. van Boxtel, the lead researcher, said.
Boxtel and his colleague Christof Koch found evidence of rivalry in this reference frame, with surprising effects on the better-understood spatial conflict.
In their experiments, the researchers created spatial conflict with a "motion quartet," which changes the arrangement of four dots. If the dots are displaced in certain ways, the visual system isn't sure if the movement is vertical or horizontal.
If the dots move to an altogether different space, there's no rivalry. Then the researchers upped the perceptual ante by creating an object reference frame with three white discs and shifting it, too, along with or in opposition to the smaller dots.
Seven male and female participants viewed the changing arrangements in four conditions. In one, both dots and discs remained stationary, in each of two, either dots or discs moved right or left, in the fourth, both moved horizontally together creating ambiguity in the frame.
Each time, participants had to press a button indicating whether the dots moved horizontally or vertically. The presses were analyzed for perceived movement "bias" and duration-evidence either of rivalry or visual clarity.
They found that even when the dots moved to another space altogether, so there was no spatial conflict, the moving discs created the effect of perceptual ambiguity. But the researchers also found that visual rivalry disappeared when the dots were stationary and the disks moved.
The study will be published in Psychological Science. (ANI)
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