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Aging Brings Big Changes in Visual Perception (SciAm MIND Jan/Feb 2016)


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This one is not online so I scanned and OCR'd the print mag article just for you good folks ;)


I like this ageing biomarker as it's fun, cheap and easy to do. Portable, too, in case you want to show it on your phone.




The Age of Illusion
How we perceive illusions offers clues to how the brain changes as we age
Aging causes significant changes in visual perception, even in healthy people with no dementia or eye disease. As a result, many people struggle with simple daily activities as they age—things like driving safely, walking on uneven ground or negotiating stairs. Unfortunately, the mechanisms underlying age-related defects in perception are not well understood. Few studies have investigated the kinds of perceptual changes that occur through adulthood, particularly in older individuals, and even fewer have correlated those changes with brain function and eye movements.
But visual illusions have begun to provide some important insights in this area. Because we know that specific ocular or brain mechanisms mediate certain illusions, how our perception of them alters with age provides clues to how aging affects related brain cell populations. These shifts also lay plain that the existence of illusions is not just an accident or mistake of evolution. Illusions are part and parcel of our perception, and their degradation with age—which, let’s be clear, makes the observer see the world in a more accurate and less illusory fashion—indicates that some aspects of illusory perception may have enhanced survival. Such an advantage becomes less important as brain function decreases in senescence.
Other types of visual impairments can help us understand neuro-degeneration in the aging brain. Yet illusions may stand Out above other visual biomarkers because older vision scientists—them selves experts in illusory perception— are acutely aware when their own observations do not match those of their younger experimental test subjects. It is one thing to have back pain, or to lose the ability to run an eight-minute mile, or to have trouble memorizing phone numbers. Those problems are all annoying. But when an amazing new illusion fails to work for your brain—especially when all your younger colleagues are agog—it is downright unnerving. It certainly focuses the mind and makes those neuroscientists wonder if they may be slowly losing theirs.
Lothar Spillmann, currently a visiting professor at the National Taiwan University, is a case in point. Spillmann spent most of his career at the University of Freiburg. Then he turned 65—the German university system’s mandatory retirement age—and he had to hit the road to find continued employment abroad. Now 77, he remains a highly productive scientist and serves as an international elder statesman for perceptual science.
As a world leader in his field, Spillman has discovered a number of important misperceptions, including the Ouchi Spillmann illusion, which produces a motion effect that we described previously in this column. So you can imagine Spillmann’s concern when—the same year he retired in Germany—he discovered he was blind to perhaps the most significant illusion of the past two decades, Akyoshi Kitaoka’s Rotating Snakes.


Above: Rotating snakes illusion

When most people look at Rotating Snakes—rendered here in the shape of a brain by neuroscientist and engineer Jorge Otero-Millan—they perceive illusory motion. Geneticist and painter Alex Fraser and biologist Kimerly J. Wilcox, both then at the University of Cincinnati, first discovered this type of illusory motion in 1979, when they elicited the effect from repetitive spiral arrangements of sawtooth-edged shapes shaded light to dark. Fraser and Wilcox’s illusion was not nearly as effective as Rotating Snakes, developed more than 20 years later by Akiyoshi Kitaoka, but it did spawn a number of related illusions. This family of perceptual phenomena is characterized by the periodic placement of colored or grayscale patches of particular brightnesses. In 2005 neuroscientist Bevil R. Conway, then at Harvard Medical School, and his colleagues showed that Kitaoka’s illusory layout activates motion-sensitive neurons in the visual cortex, providing a neural basis for why most of us perceive rotation: we see the snakes spin because our visual neurons respond as if we are in the presence of actual motion.
In our own research with Otero-Millan, now a postdoctoral fellow at Johns Hopkins University, we found a direct relation between the perception of this rotation and the production of transient eye movements, including eyelid blinks and tiny involuntary eye jerks called micro-saccades. Could age-related eye-motion failures explain why Spillmann and other older people have trouble seeing the ‘snakes” rotate? Maybe. But the Ouchi-Spillmann illusion—which Spillmann does still perceive—also appears to rely on eye movements. So it may be that certain visual processes, such as motion perception, motion adaptation or brightness perception, which are also susceptible to aging, have a differential involvement in one illusion versus the other. Or the age-related loss may reflect a combination of oculomotor and visual deficits.




Above: Rotating tilted lines illusion

In a 2009 study, psychologists Jutta Billino, Kai Hamburger and Karl Gegenfurtner of the Justus Liebig University Giessen in Germany tested 139 subjects—old and young—with a battery of illusions involving motion, including Rotating Snakes. They found that older subjects perceived less illusory rotation than younger ones, not only in Rotating Snakes but also in the Rotating-Tilted-Lines illusion, depicted above.


Above: Pinna illusion

To experience this illusion, move your head forward and backward as you fixate on the central area (Or alternatively, hold your head still and move the screen or page you are reading). Most young adults see illusory motion: the ring spins against the central and surrounding regions. But the Pinna illusion (above), which was the first to create a rotating motion effect, works for most observers, regardless of age: as you move your head (or the image) forward and back, you will see the inner and Outer rings rotate in opposite directions.
Whatever causes these various percepts to change with age is not simply a failure to perceive illusory movement but reflects ongoing changes in the brain or visual system. We hope these findings will lead to future research and a more nuanced grasp of the mechanisms underlying our perception of real and illusory motion, as well as the specific neurodegenerative effects of aging on different brain circuits.
• Japanese Optical and Geometrical Art. Hajime Ouchi. Dover Publications, 1973.
• Perception of Illusory Movement. Alex Fraser and Kimerly J. Wilcox in Nature, Vol. 281, pages 565—566; October18, 1979.
• Neural Basis for a Powerful Static Motion Illusion. Bevil R. Conway, Akiyoshi Kitaoka, Arash Yazdanbakhsh, Christopher C. Pack and Margaret S. Livingstone in Journal of Neuroscience, Vol. 25, No. 23, pages 5651—5656; June 8, 2005.
• Age Effects on the Perception of Motion Illusions. Jutta Billino, Kai Hamburger and Karl Gegenfurtner in Perception, Vol. 38, No. 4, pages 508—52 1; 2009.
• Microsaccades and Blinks Trigger Illu sory Rotation in the “Rotating Snakes” Illusion. Jorge Otero-Millan, Stephen L. Macknik and Susana Martinez-Conde in Journal of Neuroscience, Vol. 32, No. 17, pages 6043—6051; April 25,2012.
• The Neuroscience of Illusion. Susana Mprtinez-Conde and Stephen L. Macknik in Scientific American, Special Edition, Vol. 20, No. 13, pages 4—7; Fall 2013.
ABOUT the AUTHORS: Stephen L. Macknik and Susana Martinez-Conde are professors of ophthalmology at SUNY Down state Medical Center in Brooklyn, N.Y. They are the authors of Sleights of Mind (2010), with Sandra Blakeslee (http://sleightsofmind.com), winner of a Prisma Prize for best science book of the year.


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Thanks Khurram!




It frustrates me to report that while I see a lot of motion in the Pinna illusion and tilted line illusion when I move my head in and out relative to the screen, with my head motionless I don't really perceive motion in either the tilted line or rotating snake illusions. Perhaps a sign my brain is getting old. :(xyz  I'm 51.


Below are the three illusions, including Pinna (which everyone should see if you move your head forward/backwards), the tilted line illusion (keep your head still see if you see motion) and a different version of the rotating snakes illusion (again keep your head still and look for motion).


Perhaps other people would be willing to share their results?




Pinna Illusion (move head in and out relative to screen to see motion)





Tilted Line illusion (keep head still and stare at the middle. Do you see illusory motion?)




A different (perhaps more compelling?) version of the rotating snakes illusion (stare at the middle. Do you see illusory motion?)



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It frustrates me to report that while I see a lot of motion in the Pinna illusion and tilted line illusion when I move my head in and out relative to the screen, with my head motionless I don't really perceive motion in either the tilted line or rotating snake illusions. Perhaps a sign my brain is getting old. :(xyz  I'm 51.


Ditto on having some trouble with tilted lines --- they do move, tho'. I have the print version, too, but paper or screen the effect does not change.


I've been interested in optical illusions for a long time ... and, IIRC, these types effects used to move more (in my youth; i'm 48 now). 

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Most of them worked for me -- except the first rotating snakes. 


I'm 76.5  -- but I'm a full time employed university math. prof., teaching classes and doing original research.  My last research book, "A Non-Hausdorff Completion", was published by World Scientific last July.


Mathematics involves, among other things, visual perception -- so maybe I have an unfair advantage.


Or, maybe, the increased use of reasoning might tend to maintain brain health.




  -- Saul


  -- Saul

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Like Khurram, I seem to recall experiencing these types of illusions much more dramatically a few years ago...


Although It makes for good, sellable pop-sci articles, the overall importance of non- or slower perception of a couple of man-made optical illusions is not clear. 


IAC ...


In the future, I think I'll expand this topic out to include other senses along with their concomitant mind/brain connection. E.g., psychoacoustics (see*** below), muscle memory, etc.


I posted on the topic of middle-age intelligence on the List a few years back (damn those lost Archs!). An extended middle age is very new to human evolution so it's unsure how the body/mind/brain will react to life between 40-65. That said, and to cut to the chase, the middle-age brain may, in fact, be better in many cognitive tasks (compared to younger)**. It's possible that the "loss" of certain visual-illusion perception -- like the "tests" above -- means a gain in visual intelligence. The brain may simply be discarding trivial microsaccades and blinks for more important processing/problem-solving. Maybe by this time in age (evol. speaking) , it was the younger folks that were doing the chores that required fast visual acuity (hunting, fighting). The older were ... well ... old and wise, waitin' back at home for the young un's to bring home the groceries ;)


** Resources:

The Secret Life of the Grown-up Brain: The Surprising Talents of the Middle-Aged Mind--book by Barbara Strauch

[the book] Draws on new research to examine the brain's peak capacity in middle age, explaining how a growth of white matter and brain connectors enables improved judgment, cognitive function, and problem solving.


*** Personal account of audio/music/hearing.

Yup, freq, response has dropped since youth, so that biomarker is on track based on age. I can claim that psycho-acoustically, which is not part of de facto audiometry tests, I can notice some improvements. E.g., ability to adhere acoustic attention is improved (e.g. when listening to a symphony over earphones, the ability to discern instruments, timbre, rhythm and temporal cues, etc seems improved.) Agreed, some of this may be due to experience (learning, training, exposure); but that's also applicable to those who do better with visual biomarkers.

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The brain-shaped 'rotating snakes' doesn't work too well for me either (I suspect that illustration is more fanciful than functional - just to tie in to brain/aging). Is there someone in their 20s that can chime in???


This page has a better rotating snakes:



(says it requires flash, but mine worked without it)

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Thanks Tim!


That version is a lot more compelling for me too - I can see the snakes moving, especially when I move my eyes across the image and/or look at it out of the corner of my eye. Here is the non-flash version, which for some reason works better for me than the seemingly similar one I included above. Maybe I'm not so old after all.  :)xyz





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