[From Bill Powers (2006.09.01.1656 MDT)]
Rick Marken (2005.09.01.1540) –
I’m not sure I’m convinced that
the switch in the Necker Cube requires an
explanation in terms of a change in imagined
orientation.
Not imagined orientation – imagined data from which the brain would
compute 3-D orientation and present it as a perception of depth. The
usual Necker cube, drawn as if projected using parallel light rays, is
exactly how the cube would look in either orientation; there would be no
difference. It contains exactly zero depth information. Thus if you
perceive a 3-D cube in either orientation you must have supplied some
information of your own to create the impression of depth.
My perspective example shows that there is information in the way the
lines converge that would favor one orientation over the other; this
makes it harder to achieve and hold the appearance when the orientation
creates distortion. the imagined information is inconsistent with the
actually perceived information, at quite a low level, perhaps
configurations.
Couldn’t it just be that the
lines (depending on where the fixation is) provide sufficient input for
3-D object perceivers to produce a fairly strong perceptual signal?
Subjectively, it seem like the orientation (in space) perception happens
after I perceive an object.
But there is nothing to create the impression of three dimensions at all,
in the infinity projection. Neither binocular disparity, nor perspective,
nor dimming with distance, nor texture, nor any of the other cues is
present. If you see depth at all, you are imagining whatever it is that
tells your brain to perceive depth. Or you are directly imagining the
depth signal attached to various parts of the figure. Judging from the
difficulty there is in switching, I would guess you are imagining the
lower-order information, while the higher-order systems slowly figure out
the big picture.
I’m afraid I just don’t think it
would have been a very good idea for an
intelligent designer (or a random evolutionary process, for that matter)
to
have allowed imagination to have much of a role in real time control
of
perception.
It’s not good to control something that is entirely imagined if you
depend on (and think you are) controlling a corresponding real variable
outside you (like food intake). But if you’re trying to figure your way
out of a maze, or solve any other problem where you have to think of a
lot of alternative possibilities and test them for feasibility at least
in principle, you will be much better off controlling imagined
perceptions instead of real ones.
I think that when
imagination does have a significant role in
control of perception (on the input side) we see that as clearly
dysfunctional; I think it’s called psychosis.
You’re not leaving much room for control of imagined perceptions – that
is, problem-solving, planning, and just plain thinking.
I would consider the lady’s
thing with the vase a bit nutty if all she really cared about was the
appearance of the vase. But my guess is that it was just the fact that
the vase was broken that was the problem. There was no imagining
required to know that the vase had been cracked.
Unless you’re actually looking at the crack, imagining/remembering is the
only way of knowing about it*.*
So changing it because
it had been cracked would make sense, whether she could see the crack
when the vase was turned or not. But if all she cared about was how the
vase looked, then replacing a vase that looked fine just because she
could imagine the invisible crack on the other side would seem a bit nuts
to me.
So, you have proven that you can control various scenarios composed of
purely imaginary elements, like the lady and her vase, and draw
conclusions from these imaginary observations about the mental state of
your model of the lady. A very useful ability that human beings have. We
don’t actually have to put out our eyes to imagine what it might be like
to be blind. We can run models in our heads and observe their behavior,
which will tell us what would really happen (if the models are accurate)
without our actually having to produce a real result or a real
perception. You’re being pretty judgmental about this figment of Oliver
J. Lee’s (and now your) imagination. Is the point of all this that when
you perceive something, you see what is actually there? Whereas the
imaginary lady, who doesn’t perceive as accurately as you do, is
psychotic when she doesn’t want a vase that has a crack in it (and has
probably lost all its market value)? Maybe she should sell you the vase
for what she paid, and just tell you to turn the crack to the wall and it
will look as good as new. Would you pay as much for a vase you were told
had a painted-over crack down one side, but looked perfectly intact, as
you would pay for a perfect one? Couldn’t there be something beside
psychosis behind preferring the perfect one?
I think you’ve put in enough time and effort trying to prove that your
original statements about imagination not affecting perceptions were
right. It’s time to switch sides and try to prove that you were wrong.
The trouble with trying to prove your ideas are right is that you tend to
think up examples that support it, and miss alternative scenarios in
which the contrary is just as obviously true. I’ll bet you didn’t see
that the lady could have a perfectly good economic, artistic, or
practical reason for not wanting to see that worthless and falling-apart
vase looking deceptively pretty on her mantlepiece. But it’s still only
worthless and falling apart because of what she remembers, knows,
imagines in addition to what she sees. Even if all she knew about the
other side was that the color was different in one large patch – a mere
difference in sensations – she would not perceive the same configuration
of sensations as she would if she imagined the same color all over the
vase.
But I shouldn’t be doing this – you should.
Best,
Bill P.
