Re: [visionlist] immunity from illusions (particularly visual illusions)

Hi Katherine,

My guess is that some component of their inability to ‘see’ the illusions was due to a response bias to say that they do not perceive illusions.  As Michael Bach mentioned, not seeing some illusions would suggest a problem with normal vision (e.g., the checker shadow illusion).  

I would recommend actually testing one of those students under lab conditions with a set of robust illusions that have stimulus parameters you can vary, and which require some sort of forced choice response, and measure their RTs as well.  Under those conditions, assumedly some illusory perceptions would show themselves.

Best  wishes,


On Sun, Feb 12, 2017 at 11:33 AM, Michael Herzog wrote:
Dear All
We just recently reported that there are few significant correlations between illusion magnitudes:
Thus, maybe just an instantiation of variability……
All the best
Qasim Zaidi wrote:

There are individual differences, but they have not been much studied
until the recent push by Jeremy Willmer at VSS.
I had a brilliant undergraduate at Columbia, who went on to be a star
grad student at MIT, has done start-ups, been CTO of multiple companies,
won an Emmy, etc etc, and he had no simultaneous brightness or color
induction, as measured by objective methods (nulling on a 2AFC adaptive
staircase).  He was also a meticulous observer in motion experiments,
where he saw all kinds of effects.
You may want to see what else is different about these students.  I
suspect that they will be normal on low level detection and
discrimination experiments, but that may still be worth checking.
Qasim Zaidi PhD
SUNY Distinguished Professor
Graduate Center for Vision Research,
State University of New York College of Optometry,
33 West 42nd St, New York, NY  10036.
Office: 212-938-5542; Lab: 212-938-5756; Fax: 212-938-5537
*”Dr. Katherine Moore” < >

Dear vision experts,
I was hoping some of you could help me out with something that made me
curious all of last semester. Last semester was about the fifth time
I’ve taught Sensation & Perception. Even though my classes are small
(less than 25 students), each time I teach this course I have a student
or two who is unusual in some sensory way — just one working eye,
synesthesia, no sense of smell, blind, prosopagnosia, etc.
This past semester I had two students who did not experience illusions
(out of just 10 students!) One of them truly did not experience any of
the illusions. Another did not experience the vast majority of them. We
mostly did visual illusions, but among the few auditory illusions we
did, these students didn’t experience them either. I have no reason to
think the students were lying about it–they are very sincere people.
And they both had trouble with an assignment that required students to
view some new illusions, describe what they saw and what was really
happening, and explain the illusion. These two students didn’t see what
the rest of the class saw, and only saw “what was really happening.”
The illusions spanned the course, which is to say they touched upon many
different causes. For example, the Hermann grid variations, including
the “disappearing dots” one that went viral this summer/fall were
affected, as well as the color constancy and size constancy ones like
the checkershadow illusion, Ames room, etc.
What do you all know about this, like what the cause could be for this
immunity from illusions of many kinds, or individual variation in the
experience of illusions?
Katherine S Moore
Assistant Professor of Psychology
Arcadia University
450 S. Easton Rd
Glenside, PA 19038
Office: Boyer Hall room 128
Phone: (215) 517-2429




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