Comments on: Vision Sciences Stuff — a moving color demo http://theinvisiblegorilla.com/blog/2010/05/10/vision-sciences-stuff-a-moving-color-demo/ the many ways our intuitions about the mind deceive us Fri, 02 Dec 2011 12:47:53 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Daniel Simons http://theinvisiblegorilla.com/blog/2010/05/10/vision-sciences-stuff-a-moving-color-demo/comment-page-1/#comment-394 Daniel Simons Fri, 14 May 2010 03:49:27 +0000 http://theinvisiblegorilla.com/blog/?p=366#comment-394 Thanks for commenting. I really loved the demo even though I'd beg to differ with the interpretation. I am familiar with both of the alternatives you raise, of course. However, I don't think either really applies here. Both assume that the dot colors are actually being represented for more than an instant. The alternative I favor is that subjects need not have much of a representation of the dots at all. If they're just living in the moment, they would notice large instantaneous changes but not small ones, and they wouldn't notice progressive changes that take a while to occur. The change from the current state back to the original state is a large, instantaneous change that produces big luminance changes in that instant. The change from the current state to a nearby current state produces less of a signal. Note that this sort of change detection doesn't require a detailed comparison to a long-gone representation. It just requires perception of a luminance signal at that moment (one instant to the next). Note that this same critique applies to the earlier studies of progressive orientation and luminance changes by Andrew Hollingworth. If people are just comparing the current state to the immediately preceding one, then a change back to the original scene is a huge change. They're not really updating. Their just representing in the moment. Thanks for commenting. I really loved the demo even though I’d beg to differ with the interpretation. I am familiar with both of the alternatives you raise, of course. However, I don’t think either really applies here. Both assume that the dot colors are actually being represented for more than an instant. The alternative I favor is that subjects need not have much of a representation of the dots at all. If they’re just living in the moment, they would notice large instantaneous changes but not small ones, and they wouldn’t notice progressive changes that take a while to occur. The change from the current state back to the original state is a large, instantaneous change that produces big luminance changes in that instant. The change from the current state to a nearby current state produces less of a signal.

Note that this sort of change detection doesn’t require a detailed comparison to a long-gone representation. It just requires perception of a luminance signal at that moment (one instant to the next).

Note that this same critique applies to the earlier studies of progressive orientation and luminance changes by Andrew Hollingworth. If people are just comparing the current state to the immediately preceding one, then a change back to the original scene is a huge change. They’re not really updating. Their just representing in the moment.

]]> By: Jordan Suchow and George Alvarez http://theinvisiblegorilla.com/blog/2010/05/10/vision-sciences-stuff-a-moving-color-demo/comment-page-1/#comment-393 Jordan Suchow and George Alvarez Fri, 14 May 2010 03:39:49 +0000 http://theinvisiblegorilla.com/blog/?p=366#comment-393 Glad you enjoyed the demo. We aimed to distinguish two accounts of our observers' failure to notice the rapid color changes: <em>freezing</em> and <em>silent updating</em>. (Here, <em>freezing</em> means having an outdated representation, and <em>silent updating</em> means having a current one. For an example of color-freezing in vision, see [1].) You correctly note that there is a big change in luminance at the moment the display reverts to the old colors. This isn't a defect — it's critical to the design. A change in luminance implies a difference in luminance before and after the change. However, from the vantage point of an observer who holds an outdated representation, the reverted display is identical to his outdated representation. With no differences, there is no change to detect. Since our observers do detect a change, it confirms that their representation is not outdated, ruling out the freezing account. Like you, we are also intrigued by interactions between the mechanisms that detect motion and flicker. We didn't have time to talk about it, but we've done experiments to address this directly — stay tuned. -Jordan Suchow & George Alvarez [1] Motoyoshi, I. (2007). Temporal freezing of visual features. <em>Current Biology</em>, <b>7</b>, 404-406. Glad you enjoyed the demo.

We aimed to distinguish two accounts of our observers’ failure to notice the rapid color changes: freezing and silent updating. (Here, freezing means having an outdated representation, and silent updating means having a current one. For an example of color-freezing in vision, see [1].) You correctly note that there is a big change in luminance at the moment the display reverts to the old colors. This isn’t a defect — it’s critical to the design. A change in luminance implies a difference in luminance before and after the change. However, from the vantage point of an observer who holds an outdated representation, the reverted display is identical to his outdated representation. With no differences, there is no change to detect. Since our observers do detect a change, it confirms that their representation is not outdated, ruling out the freezing account.

Like you, we are also intrigued by interactions between the mechanisms that detect motion and flicker. We didn’t have time to talk about it, but we’ve done experiments to address this directly — stay tuned.

-Jordan Suchow & George Alvarez

[1] Motoyoshi, I. (2007). Temporal freezing of visual features. Current Biology, 7, 404-406.

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