Today’s reading delves deep into the visual system, so hold your breath and get ready to dive in. It’s “Sound-aided Recover from and Persistence Against Visual Filling-in” by Bhavin Sheth and Shinsuke Shimojo of Caltech (Vision Research, 2004). I even found a PDF link for this one.

Ignaz Paul Vital Troxler (1780-1866) was a Swiss physician and philosopher who discovered a simple visual effect that continues to be studied today. Because his work generates so much research interest, there is even a Web site devoted to his life and work. The effect he discovered is aptly named “Troxler fading” and can be observed in a number of different circumstances. The basic effect is simple: stare at a colored figure where the center is a contrasting color from the background color. Within a minute or so, the center will appear to fade into the background. It eventually completely disappears. Try it yourself here. There is no trick to the site; it’s a simple .gif file.

Are you sufficiently amazed yet? The effect is pervasive, and can be generated in a number of different ways, but what’s truly important about it is what it tells us about the visual system. The eye is a lot like a camera, but the way we “see” the images our “camera” produces is very different. The eye has a lens, and even “film” (the retina), which detects light focused by the lens. The signal from the retina is then sent to the brain via a complex process, and it is only after the information has been processed in a number of ways that we actually “see” anything. What we see may have been initiated by the chemical response of cells inside our eye, but the processes going on inbetween that and our consciousness of “seeing” something have an important effect: what we “see” is not always what our retina “sees.”

Troxler fading is a clear example of a disparity between the retinal image and what we see, so it provides a critical opportunity to understand how vision works. The same effect can be generated by presenting a flickering object. Watch a contrasting image that flashes randomly on the screen in the same spot for a minute or so, and it will eventually fade away.

What our mind appears to be doing is maximizing efficiency. If we keep getting the same uninteresting signal, over and over again, eventually we just ignore it — those brain cycles can be used for something else. But what can cause us to pay attention again? That’s what Sheth and Shimoju wanted to explore, so they devised an experiment to find out. They asked people to stare at a white cross on the middle of their green computer screen, then flashed two red dots — one on each side of the cross — randomly until they both faded from view. They then began to play a clicking sound, synchronized with the appearance of either the left-hand or right-hand dot. Remarkably, when the click was played, the participants could again see the corresponding dot, but the other dot remained invisible.

So sound can affect the way we see objects before we are even conscious that the object is there. The effect is so strong that even when the opposite dot’s brightness is doubled, viewers see the two dots equally well. If the sound is played from the beginning of the experiment, only the object with no accompanying sound “disappears” from view. Even though the sound does not come “from” the object, sound causes us direct our attention to the thing that is changing. Ventriloquists rely on this phenomenon as well. We hear speech, and we see the dummy’s mouth move, so we assume the dummy is the one doing the talking (when we all know the real dummy is the one with his hand up a doll’s tuckus!).

Perhaps the larger point is an incisive window into the way the mind works. The brain is a collection of expert systems: for vision, for language, for touch, smell, emotion, and a host of other skills. These systems can work independently, but they are also connected in remarkable ways. This evidence showing the connection of the auditory system with the vision system is just one of them.

Now that 8 million of us have blogs (sorry, can’t remember where I got that figure), you’d think some of the mysteries of blog design would be sorted out. For example, why does everyone put the goofy little calendar in their menubar? What purpose does it serve? Does anyone ever scroll down to the calendar and say to themselves, “hmmm… I wonder what Munger said on the 21st of January. Let’s click here and see.”

No, no one ever does. Of course, I do have the calendar on my site, though I’ve thought many times about taking it down. I keep it there because it’s a reminder of my own industriousness (or lack thereof). It’s a point of pride for me to blog every weekday, and the calendar-thing lets me know if I’m keeping at it. Come to think of it, I guess that’s probably what other people use them for, too. People can visit my blog and quickly note that I’m a weekday blogger. Others blog in fits and starts, and still others can’t go half an hour without posting something. The calendar gives you a quick visual impression of what type of blog you’re dealing with.

I guess that’s not much of a peeve. But this one is: don’t you hate it when you want to link to a blog and you can’t immediately tell how to link to a particular post. The best blogs offer a convenient “permalink” link for just that purpose. Mine doesn’t, though. You have to click on the title of the blog post to get the permalink address. That’s not so bad, either — it’s pretty clear from the visual arrangement of my site that that’s what you need to do. Other blogs put the “permalink” in the time stamp of the blog post. This strikes me as amazingly counterintuitive. Why would I ever click on “7:51 a.m.”? Worst of all is when you need to click on the name of the person posting the article. Shouldn’t a click here bring up all the posts by that person? Or maybe an e-mail address? Half the time I end up clicking on the name, just to check to see if it’s the permalink, and all the sudden my e-mail app opens up. Ugh!

Here’s a relatively minor one: the “comments” link. Many blogs (including mine) use this link for a dual purpose: to let readers know the number of comments so far, and to take them to the commenting engine. But if there are no comments yet, the link shouldn’t say “no comments.” This suggests that comments aren’t allowed.

And why do some blogs have text widths that go from here to Albania? I think I keep my browser window at a reasonable width: it covers about 800 pixels of my screen, or roughly the width of a sheet of business paper. If your text can’t fit on 800 pixels, it’s TOO WIDE! That’s like writing a business letter with no margins — and then some. That’s like a newspaper that carries narrow lines of text all the way across the entire page. It’s almost impossible to read. I’ve seen blogs formatted so wide that I can’t see the whole thing, even when I stretch my browser window to the full 1024 pixel width of my screen. Enough, already!

Finally, the blog title. The title of your blog should do something, people! What should it do? Take visitors back to the home page of your blog. What if someone finds your blog via a link from another blog. They won’t be on the home page, and if they actually like your blog, they want to see what else you’ve done. Make it easy for them!

Oh, and one more thing… don’t you just want to puke when people make their sidebar some gaudy color like purple? Or yellow — that’s the worst. Especially when they’ve got some dorky animated logo. And don’t get me started on disingenious wordplay with blog titles and author names…