Today’s reading is “When Sound Affects Vision: Effects of Auditory Grouping on Visual Motion Perception,” by Katsumi Watanabe and Shinsuke Shimojo of Caltech (Psychological Science, 2001).

In 1997, Sekuler, Sekuler, and Lau discovered a fascinating effect that I’ve attempted to replicate using the crude resources available to me (iMovie). I’ve made two movies (quicktime required) that (perhaps with a little imagination) replicate the effect. First watch movie 1:

movie 1

It looks like the two balls pass through each other, right?

Now, make sure you have the sound turned up on your computer and watch movie 2.

movie 2

You should hear a clicking sound, right as the balls meet. Now it looks like the balls “bounce” off each other, right? But the display was identical — the only thing I changed was to add the sound to accompany the “collision.” The simple soundtrack changed your visual perception of the event. Nearly every observer Sekuler et al. showed similar movies to saw it the same way.

Watanabe and Shimojo wanted to know how this effect works. Does any sound at the time of “collision” cause the bouncing effect, or do only certain types of sounds work? So they asked observers to do the same task, but instead of playing a single sound, they played three separate clicks — one before the collision, one at the time of the collision, and one after. Now observers saw the balls pass through each other again.

Next they played a series of tones, but they changed the pitch of the tone simultaneous with the collision. Again observers saw the balls “bouncing” back to their original positions. Watanabe and Shimojo believe this is due to a phenomenon called “auditory grouping” — we don’t hear the series of clicks as separate, disconnected sounds, but as a single group. By changing the pitch of one of the sounds, they cause observers to ungroup the sounds, and this in turn causes the bouncing effect to reappear.

The bouncing effect is yet another example of how our auditory system is linked to the visual system. It’s part of the reason that staged fistfights and swordfights seem “real” — we’re often fooled even by fake punches that “miss” by a foot or more, as long as they’re accompanied by an appropriate sound effect.

When I was a cub reporter on my high school newspaper, our adviser did one of the few good things he’d ever done for us: he explained freedom of the press. He did a good job of it, too — I still remember what he told us after all these years. Freedom of the press wasn’t just some abstract concept: it reached all the way down to us peons writing for the Garfield Messenger and printing it in the on the old A.B. Dick presses in the graphics room down the hall.

You see, he told us, freedom of the press meant we had real freedom, even us kids. But we also had responsibility. We could print whatever we wanted — anything — and there was nothing the principal or anyone else could do to stop us. That was called “prior restraint,” and it wasn’t allowed, even for a bunch of geeky highschoolers. We could be disciplined afterwards, and the printed papers could even be removed if what we wrote caused a disruption at school, but no one could censor what we wrote before it went to press.

A few months back I did a search for “Garfield Messenger” online and was surprised to find that they now had a very impressive Web site, well designed, with up-to-date articles. As I was writing this post, I looked for the site again, and found it, here. Unfortunately, now there is only a two-sentence notice, “At the request of Messenger staff adviser Steve Miranda, this site has been taken down. We hope to restore it soon.”

Steve Miranda was not the adviser back when I wrote for the paper. I don’t know what our adviser would have done if we’d had a Web site back in those days. How can there be “prior restraint” with a Web site? Once it’s up, it’s up. It could be up for 30 seconds, then taken down because of potential for disruption.

There’s been some commentary around the blogosphere (John Shirley link may expire — sorry) about how high school students these days don’t understand their constitutional rights or don’t believe they are reasonable, how many kids don’t approve of freedom of speech.

As one student pointed out to BoingBoing, many rights don’t apply to kids. No freedom of speech, or assembly, or from search and seizure for them. That’s part of why I was so amazed that we did have freedom of the press. But now, with the Internet washing away the concept of prior restraint, it seems kids no longer have even that.

John Shirley makes an excellent point about the dual world kids live in.

Usually parental types (I’ve got three sons) push for more conservative-that is, careful-behavior. But some of these kids seem to have a hunger to restrict freedoms, free speech. Why? Recently a teen we know told my wife that he wished he “had more restrictions”. But he kicks if anyone tries to really restrict him. You hear that a lot-young people at once resenting limits and craving them. Could be they’re quietly freaked out by the wilderness feeling that the world gives them-mass media and the financial landscape seem, together, a kind of wilderness, more a jungle than ever, a sickening plethora of vapid choices.

I was going to add “these days” to my lead-in, but I think it’s always been that way. Even as a kid reporter for my newspaper, I felt more paralyzed than liberated by my freedom. Wouldn’t it just be easier if they told what we could and could not print? If they treated us like kids all the time, instead of picking and choosing?

It might have been easier, but it wouldn’t have been right. I don’t know why the Messenger has been taken offline, but I hope these kids get back at least that one freedom soon.

UPDATE: The Messenger’s Web site was back up as of noon today (2/3/05)