Do chromatic variations have an effect on motion perception and multi-partite illusions?

Maria Fernanda De La Torre

In their paper, “Color brings relief to human vision,” Frederick A A Kingdom showed that there are circumstances in which color contrast promotes luminance contrast for visual form judgements by superimposing luminance-defined gratings with right-oblique color-defined gratings that results in a 3-dimensional plaid that appears corrugated in depth. What I found interesting about this illusion and many other bi-partite or multi-partite percepts is that prolonged fixation on these stimuli results in one of the component gratings fading and causes the percept to switch between the two states of either depth perception and just one of the color/luminance-defined gratings.

In this illusion, I am interested in whether continuous chromatic variations of either the background or the objects can cause color adaptation and consequently, have an effect in motion perception and whether these chromatic variations can affect the length of a perceived state in multi-partite illusions.

As an attempt to answer this question, I present different illusions on both a gray background and a dynamic color-changing gradient background. The illusions were inspired by some existing illusions, some based on color adaptation, the reverse rotation effect and Moiré patterns.

The first row is a static wheel-like design, one way to look at this first row would be to fixate on the center of the figure on both backgrounds. On the right, do you notice the luminance and sometimes the apparent color changes as the background changes? This might happen because of color adaptation, since the color that is visible continuously leads to desaturation and interruptions by a nearly opponent color counteracts this desaturation. Does the wheel on the right seem to be moving slightly?

The second, third and fourth rows have wheels rotating clockwise. These might create an illusion similar to the wagon-wheel-effect (reverse rotation effect) and each row just varies the color of the wheel. This illusion happens in both backgrounds. Stare at the center of the wheel for some time, in the first few seconds, the lines might slightly change in shape and width. After more time, the will might seem as if it was rotating counter-clockwise. If you are able to perceive this change, notice that the percept of the wheel rotating counter-clockwise is soon taken over by the real clockwise movement of the wheels. Is the amount of time or frequency in which the wheel switches in rotational states affected by the background on the right?

The rest of the rows are more fun, they are examples of Moire patterns. Each row just varies in colors, type of wheel, speed or superimposed location. Here we have two wheels superimposed. Here the background light has to either pass both patterns or be blocked in some cases, which results in multiplication of the two transmittance values and multiplication of patterns with similar spatial frequencies causes different frequencies to appear. In these rows, you don’t have to fixate on anything, you may notice that the two wheels will result in an apparent third pattern in the middle of the two that is moving at an opposite direction, or you might notice the wheels changing in their direction of rotation. As the background changes on the right, you might also notice one of the wheels will draw your attention over the other. Do the two backgrounds have different effects on the patterns or the duration of each pattern state?

References

Brown, R. O., & MacLeod, D. I. (1997). Color appearance depends on the variance of surround colors. Current Biology, 7(11), 844-849.

Kingdom, F. A. (2003). Color brings relief to human vision. Nature neuroscience, 6(6), 641-644.

Link, N. K., & Zucker, S. W. (1987). Sensitivity to corners in flow patterns. Spatial vision, 2(3), 233-244.

Purves, D., Paydarfar, J. A., & Andrews, T. J. (1996). The wagon wheel illusion in movies and reality. Proceedings of the National Academy of Sciences, 93(8), 3693-3697.


Comments


Maria Fernanda De La Torre

c) The subjective reports partly answer my question (I think this is because my posed question is a little vague). The reports show that the chromatic background changes do have an effect on motion illusions or that they can create illusory motion-like behavior (first row expansion/contraction). However, for some of the motion illusions, it seems that this effect mainly occurs when the background color gets closer or matches the wheel color, since these effects are not visible in the black or white wheels. For bi-partite state illusions, I think it's difficult to measure how long we spend seeing the wheels turn one way or reverse and I'm not sure that my illusion could measure that directly.
d) I think one improvement would be to just focus on one particular illusion and vary the background in terms of speed, range of colors and gradient direction. I think this change would also help with the second part of my question since seeing variations in the speed, specific colors and directions of the background might explore further the effect of the background on motion and potentially see changes in the length the observer spends looking at the wheel turning clockwise vs. reverse.


James Turrell's art looks amazing, I definitely plan to visit his exhibit once they reopen. Thank you so much for sharing!
The deformation as I looked at a different also happened to me but I thought maybe I just spent too long looking at them. I learned so much and had a lot of fun with this illusion!

Maddie C

Wow this comment box is deforming from motion adaptation and changing colour as I type...

first row- slight motion in right column compared to left. Like Malinda I don't see it spinning, I see it expanding and contracting
second row- i don't see too much difference between right and left
rows 3-5: the green wheel undergoes the most changes (turning backward, getting fuzzy, width of the lines getting thinner and thicker, slowing down & speeding up). yellow is the next one . black remains quite constant I thought
moire patterns: Yes, it's quite difficult for me to describe what is going on but I see the most changes in pattern for the green/red pair that seem to be linked to the colour changes. Some of it of course happens when one of the pinwheels almost fade into the background. I see change for the black ones too, but it doesn't seem to be linked to the changes in colour as much?


Based on this illusion, i think you might like the artist James Turrell, who plays a lot with these intense color adaptation effects. In his art, he uses them to help you lose your sense of depth perception. He has an exhibit at Mass MOCA (in North Adams, Massachusetts) until 2025.

Malinda

These are very cool illusions! I definitely see the wheel on the right in the first row moving (I see it contracting and expanding, rather than spinning, though).

In the next three rows, for me the green spiral switches direction the most and appears to be spinning the fastest. I can see the one of the left switch then the background on the right is pink.

For the final rows I pretty persistently saw all the wheels spinning clockwise (though I'll admit I couldn't look for too long since they made me a bit dizzy!)

Overall I found the first row the most compelling - I think the color changes of the background create a motion illusion.