Take a look at this amazing illusion created by Arthur Shapiro (you'll need the latest version of Flash Player to see it):
You're looking at two donut-shaped figures whose "holes" are gradually changing color from black to white and back again. It appears that the holes are changing in an opposite pattern -- when one is light, the other is dark, and so on. But if you click to remove the surrounding donuts, you'll see that the two holes are actually changing together.
Shapiro calls this the Contrast Asynchrony illusion, and he argues that it can tell us a lot about how the visual system works.
Definitely worthwhile to read the rest of the original post...
Finally, I found a recent study shows that the human brain reacts differently to people that seem like us than to those who don't through firstname.lastname@example.org via kottke.org by on 2/7/08
The experimenters used functional magnetic resonance imaging (fMRI) to scan the brains of Harvard and other Boston-area students while showing them pictures of other college-age people whom the researchers randomly described as either liberal northeastern students or conservative Midwest fundamentalist Christian students.
The study concludes that the secret to getting along with someone that you perceive as an outsider is to find some common ground so that your brain will accept them as someone with similar circumstances.
David Galbraith expands upon what this means for society at large:
In other words, a civilized society depends not on the people who are currently the most civilized, but those who are most willing to accept change, as social or cultural groupings change, split or coalesce. Inevitably this means reasonable people rather than faithful people.
As Garr Reynolds says, "If your idea is worth spreading, then presentation matters." It would seem we need to do our best to combine both the visual and the cognitive with PowerPoint and Web 2.0.