From: Eugene Frison <cthulhu_calls.nul> Date: Mon, 23 Apr 2012 15:44:46 -0500 Archived: Tue, 24 Apr 2012 12:58:15 -0400 Subject: Re: Ufology And Psychiatry - Summary >From: Cathy Reason <Cathym.nul> >To: UFO UpDates - Toronto <post.nul> >Date: Sun, 22 Apr 2012 19:04:46 +0100 >Subject: Re: Ufology And Psychiatry - Summary >>From: Eugene Frison <cthulhu_calls.nul> >>To: <post.nul> >>Date: Sat, 21 Apr 2012 19:06:42 -0500 >>Subject: Re: Ufology And Psychiatry - Summary >>What vision researchers? What are these mechanisms by which the >>brain extracts information from the visual world? What >>experimental artifacts? What hypotheses are being tested on how >>the visual system behaves in highly novel and constrained ways? >>Can you tell us what these novel and constrained ways are? What >>have these tests reveiled about how the visual system behaves in >>novel and constrained ways? Don't just claim something _is_. >>Give us something we can sink our teeth into. >The phrase about pots and kettles comes to mind, but ok. The image of one utensil being more tanished than the other comes to mind, but ok. >Let's try the example of the Kanizsa Triangle. This is an >illusion in which only the corners of the triangle are actually >defined - the sides of the triangle just aren't there. >Nonetheless when we look at the illusion we see a complete >triangle. The sides are added in by a process known as illusory >contouring. I am familiar with this illusion and others similiar to it. I like the one with the snake. >This is actually very useful. For example, out of my window now >I can see a row of houses with a tree standing in front of them. >I can't actually see all the houses, because the tree obscures >the view. Nonetheless when I look at the houses, I see a row of >ordinary houses, and not a row of houses with a peculiar tree- >shaped hole in one of them which just happens to be hidden >behind an actual tree. Although the some of the contours of the >houses are not directly visible, they are added in by the >illusory contour mechanism. >Two interesting points here: First, the mechanism which computes >these illusory contours seems actually to be quite simple. There >are a number of models for producing illusory contours, and >although we don't know exactly how the brain does it, all the >models rely on highly specific local processing algorithms. >There is no need of any sophisticated top-down interpretation by >some sort of "narrative-constructing" homunculus. >Second point: Although we're happy to call these things illusory >contours, I can't think of a single _natural_ example in which >the contours are in fact illusory. In all real-life examples the >contours really are there, it's just that they aren't _directly_ >visible. This is why vision-researchers often don't call this an >illusory contour mechanism at all, but a boundary completion >operator. If you want to say that the brain _infers_ the >boundaries, I guess that's ok, just so long as we realize that >the inferencing mechanism is actually very simple and local, and >doesn't require any sort of intelligent top-down processing of >the sort beloved by cognitive psychologists. >However - this illusion regularly appears in psychology >textbooks as an example of how unreliable human perception is >supposed to be because, it's said, we see things that just >aren't there. So do better examples like the inattentional blindness experiments such as those conducted by Daniel Simons and Christopher Chabris, and the change blindness experiments conducted by Simons and and Daniel Levin. Cathy, let's be very clear about something. I never brought up the example of these illusions. I never, at any point, used them to support my views. It is you (and David) who bring them up and keep talking about them. The only thing I ever said regarding them was that psychologists _might_ be justified in considering them as more evidence added to the pile, if the assumption that human perception is unreliable, is soundly supported by evidence from other fields of science. In fact, I stated - agreeing with you and David - that these are not the type of realities that human beings find themselves dealing with in the real world. Turn the smoke machine off! Listen to 'Strange Days... Indeed' - The PodCast At: http://www.virtuallystrange.net/ufo/sdi/program/ These contents above are copyright of the author and UFO UpDates - Toronto. They may not be reproduced without the express permission of both parties and are intended for educational use only.
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