MetaFilter posts tagged with vision and perception

Here's looking at you/me, kid

cogneuro — Thu, 28 Aug 2008 14:31:13 -0800

More good stuff for people who like visual ("optical") illusions (previously): A nice Scientific American article, a particularly creepy illusion, and a link to the "Best visual illusion of the year" contest. Given that the eye/mind/brain is so easy to trick, a person might wonder what's really out there in the world.

Ear-sighted

Kronos_to_Earth — Tue, 05 Aug 2008 20:30:02 -0800

"People with synaesthesia can’t help but get two sensory perceptions for the price of one. Some perceive colours when they hear words or musical notes, or read numbers; rarer individuals can even get tastes from shapes." (previously) Neuroscientist Melissa Saenz of the California Institute of Technology has discovered a new form [pdf] of synaesthesia. Can you hear the dots? (QT)

Chick Sexing

parudox — Mon, 19 Nov 2007 10:14:53 -0800

"Over and over he scoops up a chick with his left hand, expels its droppings with a squeeze of his thumb, opens its vent with his fingers, peers through the magnifying lenses attached to his spectacles and determines its sex." It's a dirty job (YT). Sexing chicks early is important so that the cockerels can be separated and culled^ or fed to be broilers^. The obvious differences take weeks to develop, so when the vent sexing method was developed in Japan in the 1920s, professional chicken sexers became sought after. After years of training, they can sex a thousand day-old chicks an hour with 99% accuracy. In many cases the sexer cannot say why he made a particular decision. The method is learned mostly empirically and is not open to introspection, which has made it of considerable interest to philosophers and cognitive scientists. Vent sexing is in decline, however, owing to development of feather sexing (i.e. using breeds with differences in feather length or color). Would you like to learn to sex chicks? There are plenty of resources, such as A Guide to Sexing Chicks (1935). Better yet, The Specialist Chick Sexer is a modern treatment (there is an extract and another poultry essay available). You can sex all fowl, actually. Cognitive scientists, philosophers, and psychologists all like chicken sexing. Biederman (of geon^ fame) and Shiffrar showed (PDF) that novices can be trained to decent accuracy with explicit perceptual clues. There's a discussion of chicken sexing in the defunct PSYCHE-B cognitive science listserv (more useful archive here). Scroll down to see it, particularly Bruce Mangan's post. (There was an earlier post, and the main link is good if you can get access.)

The Doors of Perception

jason's_planet — Mon, 14 Aug 2006 07:51:08 -0800

We’ve detected background radiation from the Big Bang. We’ve sent explorers to the bottom of the ocean and the moon above us. We have images of the individual atoms of which our world is made. But we cannot have direct access to the sensory experiences of another human being. Language can help to bridge the gap but it is an imperfect tool. The closest we have come is Brain Fingerprinting and even that only indicates recognition of a scene or object; it does not capture the actual visual memory of the scene or object. This may soon change. Several years ago, researchers at Berkeley wired a cat’s neurons to a computer and were able to obtain videos of what the cat was seeing.

Stereograms

Gyan — Sat, 04 Feb 2006 16:13:44 -0800

Color Stereo Stereograms Directory

Not very well, apparently

JZig — Thu, 10 Feb 2005 15:57:36 -0800

How do we see? This site by Dr. Dale Purves makes it obvious we don't see things like a camera in any way. Check out the interactive demos, test your perceptual abilities, and read the research explaining why this happens. Number 12: Color Contrast Cube is particularly startling. Warning: Totally Flash interface, but appropriate for subject matter. More experiments at a less Flash-y associate's site.

Enjoy the plasticity of your brain!

ikalliom — Sat, 10 Apr 2004 10:51:13 -0800

The McCollough effect is a visual illusion somewhat similar to regular color aftereffects, but the working mechanism is different, and despite a wealth of theories, not entirely explained. Once the effect is established, it does not seem to go away and can last for days or even weeks. Proceed at your own risk.

taz — Fri, 27 Sep 2002 01:27:26 -0800

A professor of vision science at MIT understands that life isn't just black and white, even though we often see it that way. This amazing illusion proves it, and these slick, fast-loading, Flash demonstrations of lightness perception show how it's done. (My favorite is the "Koffka Ring".) White paper here, for deeper background.