New Firefox/Firebug is a train wreck. Can't download old versions any more. Thank goodness for Time Machine backups.
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June 2009 Archives
Back from Stinson. Grabbing a burrito. Enjoying the sunshine. Link
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At stinson. Just got beat at football.
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Trying out a new Mexican joint. +1 points for a broccoli and corn burrito. -1 points for stingy salsa portions.
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I have an entire book of visual illusions, but this is among my favorites. It's been missing for several years but it turned up today during some spring cleaning. To see it, stare at the black cross until the purple dots disappear and all that remains is a rotating green dot.
This illusion is great because it makes a succinct argument why the trichromatic theory alone cannot explain color perception (the trichromatic theory says our eyes have three types of color receptors, and that the response of each is directly related to a stimulus's proximity to its preferred wavelength). In essence, this illusion draws attention to the fact that the psychological experience of seeing different colors isn't purely an additive process (like mixing paint). Were that the case, the purple dots wouldn't eventually disappear.
Trichromatic theory isn't wrong, but it's incomplete. It's true our eyes have three types of color receptors, and they do in fact respond preferentially to short, medium, and long wavelengths of light. However, immediately after a receptor is activated, its signal is subtracted from its neighbors. This mathematical derivative helps our brain decipher complex color patterns and distinguish shades of color beyond pure red, green, and blue.
In the case of this particular illusion, our eyes have cells that perform math on red and green stimuli. A collection of cells fire like crazy when there's lots of red and little green(R+G-) and others when there's lots of green and no red(G+R-). When the red dots temporarily disappear in this illusion, R+G- cells shut up, and our G+R- cells cease to be inhibited. As a result, for a brief moment the eye tells the brain that it's seeing green. A similar phenomenon is witnessed when one sees the "green flash" immediately after the sun sets (but only if you've stared at the setting sun sufficiently long beforehand).
Why do the red dots eventually disappear? My theory is that the brain realizes it's receiving a spike in G+R- without actual green stimulation and detects a ruse. The red dots sporadically, but only temporarily, re-appear as your eyes shift and different receptors re-affirm that the dots are in fact real. This leads to the subject of photoreceptor fatigue, but that's a topic for another illusion.
I have plenty of these. I think I'll post more soon.
What the Iranian leaders are saying today is frustrating to hear. It makes me want to stop purchasing their gasoline.
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Just claimed facebook.com/briantobin. All the other Brian Tobins can suck it.
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Let's go Penguins!
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Back from Drakes Bay. Tired x10. Looking forward to grabbing a falafel and watching an episode of West Wing before passing out. Good night!
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Biked down to the airport to buy sailing gear for my race tomorrow. Now stopped in Brisbane for a drink before trekking home.
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Go Penguins!
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This day is bananas.
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Holy cow Batman. Flight Control update!
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Jens Lekman rocked tonight at Bottom of the Hill! Now time for a quick sando at Love 'N Haight. Link
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Brian posted Fireworks on Roof 2
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