In an earlier comment, I indicated that I would post something on my blog to help clarify the distinction between direct and representationalist perception.
I have now done that, in a series of four posts. The first of those is
and it, in turn, contains links to the other posts.
Your turn.
keiths:
walto:
I don’t think the book itself is particularly important, but Gibson’s ideas are, as you’ll see if you google “Gibson direct perception“. Also, Gibson didn’t hesitate to discuss the philosophical implications of his ideas. He was a proponent of Thomas Reid and a critic of indirect realism.
That’s a shame, because I think motion illusions have philosophical implications. They bolster the case for representationalism.
But I don’t claim that “NO physical objects can be directly perceived.” Why am I obligated to defend a view that I don’t espouse?
Earlier, I wrote:
That was in a comment to you, by the way. I’ve made the point multiple times. Now do you begin to see why I think you’ve been ignoring some of my statements?
Well, I’ve challenged some of your statements, and pointed out where I think you’ve gone wrong (this is The Skeptical Zone, after all), but I wouldn’t characterize that as hostility. I have no problem separating the person from the argument, and I’d happily buy you (or Neil, or anyone else here) a beer if we were arguing in person.
To Neil, I get the impression you think KeithS is just being perverse or obstinate, but apparently the primary argument against direct realism is The argument from illusion. Also, I think you indicated his illusions aren’t even working for you on linux, thus presumably hampering your ability to comprehend where he’s even coming from. In my case actually, only the fourth and last illusion worked, but the fourth was good enough — at a certain point the dots just spontaneously start moving up and down instead of left and right. It also occurred to me that the experience of blind people that suddenly gain their sight in adulthood has a bearing on all this, and sure enough that as well is considered in debates of direct vs indirect realism/perception.
Sorry Keiths, didn’t figure you actually need any help.
keith s writes: But I don’t claim that “NO physical objects can be directly perceived.” Why am I obligated to defend a view that I don’t espouse?
Of course you’re not obligated to defend it. But that is the claim that is contrary to mine. You want to argue with me, obviously, but to do so you have to assert something contrary to something I’ve said. I keep pointing out that my, indeed most, direct realisms do not require that ALL perceptions of physical objects be direct. If you agree, that’s lovely. But I do get the sense, you’d prefer to argue.
You point out that you haven’t claimed that all perception is indirect; it’s also true that I haven’t claimed that all perception is direct. But the important question regarding direct realism isn’t about perception of any kind, it’s about perception of physical objects. So to see if there’s actually any disagreement between us, I’d have to know not just whether you think there is some direct perception (because, e.g., sense-data theorists believe that they can directly perceive–or otherwise apprehend–those thingies). I’d have to know whether you think any perception of physical objects is or can be direct. And again, by direct, I mean without epistemic intermediaries–whether or not there are any causal intermediaries, because pretty much everybody acknowledges those.
BruceS,
Wow, thanks for posting that! That’s indeed me, but I’d never seen that summary and didn’t even know such individual summaries had been compiled. I don’t know if you’ve taken that yourself, but it’s based on a survey that philpapers conducted. My answers were no doubt all over the place and likely even occasionally self-contradictory (I just should have put “who the hell knows?” more often). I’m afraid to look too closely at it for fear of wanting to cry. Picking responses to all those questions was almost as hard as picking winners to every NCAA tournament game–and I was likely not much more accurate–even though they’re supposed to be MY views…..
Anyhow thanks for bringing it to my attention!
Re the tone here, I’ve been at several considerably more hostile sites, and (as Neil can attest) have contributed to the pissiness myself at times (though my MO has generally focused on sarcasm and snark). I actually don’t like to fight though, which is part of the reason I’m often indirect when I do so.
People (including me at times) invest a lot of ego in their expression of their views on the internet, even when they’re posted anonymously. It’s not surprising that people like being agreed with, but a lot of people feel hurt even when there’s no response to something they’ve said. I’ve been playing in these sandboxes for about 20 years, and it all still seems wicked weird to me.
Best,
W
It’s a terrible argument.
Some philosophers, particularly objectivists, use direct perception to claim that perceptions are true and so a sound foundation for epistemology. Maybe the existence of illusions counters that epistemic claim. However, I’m not arguing for a foundation for epistemology. I’m only concerned with how to best understand perception.
JT, to Neil:
I created a GIF of the last illusion so that Neil could see it. I would convert the others if I thought it would help, but Neil’s stumbling block appears to be something other than a lack of evidence.
No worries. The more, the merrier.
walto,
That’s because you keep saying things I disagree with. If I agreed with everything you said, I would lose the desire to argue with you.
Read the thread again. There’s been plenty of that.
You questioned the relevance of the motion illusions, and I defended it.
You asked for “non-physical’ intermediates, and I pointed out that they don’t need to be nonphysical.
You stipulated that relevant intermediaries “not TAKE PLACE in or around S”, and I disputed that restriction. You then amended it.
You stated that if the intermediates are physical, then perception is direct. I disagreed and explained why.
You referred to the physical intermediate as an “object”, and I suggested that “object” was the wrong word to use when describing a pattern of neural firings.
You said that “perceiving through an intermediary” did not constitute indirect perception, and I disagreed.
God only knows (so to speak) how you managed to ignore all of the above and concoct a narrative in which there is no real disagreement between us, just a pointless desire to argue on my part.
JT:
Neil:
That would have been more persuasive if you had explained exactly why the argument is terrible.
Instead, you addressed a different argument altogether:
I’m not using illusions to argue that perception is unreliable. That’s obvious and is reflected in the word “illusion” itself. My argument is that inference is an essential part of the motion illusions, and that the perception of motion is therefore indirect in these cases.
Neil:
If my examples are “fully consistent with direct perception”, then it will be easy for you to explain why and how. Excellent. I look forward to hearing your explanations. I’ve been asking and asking for them.
I did that in an earlier post.
keiths:
Neil:
Perhaps your eyes were shut while I was making my argument. Try rereading the thread. I think you’ll spot it this time.
Continuous motion across the visual field. When an image sweeps across the retina, then there is motion available to be directly perceived. When one image appears, followed abruptly by a different image, then there is no motion in the stimulus. If there is no motion in the stimulus, then it cannot be directly perceived. It must be inferred.
What is the invariant in the case of the motion illusions, and how do you get from that invariant to the perception of motion without inference, representation, or modeling?
I’m a broken record on this one, but I still think a lot of the disagreement between you and Keith S is that philosophers and psychologists don’t use the term “direct perception” in the same way and so don’t judge evidence for and against it the same way.
For example, I read Keith as saying a valid “epistemic intermediary” could possibly be unconscious whereas as I understood your paper as saying it must be apprehended, ie something one is aware of (eg the optic nerve is not an such an intermediary, you say at one point, and I would take this as extending to any subconscious mental/neural events).
But I am not sure if I understand both of you correctly and that is one reason a posting on the philosophy aspect in particular would interest me. Another reason is that I have a general interest in understanding what philosophy says about the human experience, as compared to science, in areas like perception, where they overlap.
I see someone has posted on moral calculus for an atheist which is garnering a lot of attention. This is why I thought a post on moral realism would be popular. Looks like that person got there first. I’ll be interested to see if the relativists of TSZ are out in force yet.
keiths,
Wow, I think you know several of those disagreements are actually only apparent. At least I hope so, since I’ve explained this stuff several times now. This post of yours is an excellent example of why I said that you prefer to argue than find any areas of agreement. If you called me “Roger” in one post, and we straightened that out, it would be kind of weird for you to still be insisting that we can’t even agree on my name. But that’s what that list is–a bunch of examples of talking past one another.
While I think your post does show that Bruce is right about areas of confusion, I think it also suggests that there’s not much point trying to clear them up.
If your vision worked the way that you apparently think it should, you would be blind most of the time. To be useful, vision has to work even when you are moving. Most of the continous motion across the visual field is due to your motion.
BruceS, to walto:
Me too, though my suspicion is the opposite of yours. I think that most philosophers and perceptual psychologists mean the same thing, or something very close, when they use the term ‘direct perception’.
That’s right. And not only can it be unconscious (or preconscious), it can be involuntary. I cannot will myself out of seeing those motion illusions, even though I know they’re illusions.
walto,
Some are apparent, some are real. If we don’t address a disagreement, we can’t determine which category it falls into.
Your unwarranted condescension is noted.
That would be weird, but of course I’m doing nothing of the sort.
I’m responding to this…
…with examples in which I do exactly that.
You trained as a philosopher, right? Philosophers disagree with each other and actually express those disagreements.
Why are you surprised or disappointed that it happens here, on a site called The Skeptical Zone?
Neil:
I’m not arguing that vision “should” work that way. I’m answering your question:
The answer, again:
Neil,
Also, don’t forget my question.
You wrote:
I asked:
keiths,
Skeptical shmeptical. You obviously just like to argue, whether there are actual disagreements or not. If we don’t mean the same thing by “direct,” it doesn’t really matter too much if you think (some but not all) perception is indirect and I think (some but not all) perception is direct, does it?
I note that I did ask you a question that I thought might help determine whether and the extent to which we really DO have anything to argue about with respect to the perception of physical objects. However, you preferred not to answer that, instead repeating stuff where it’s unlikely we disagree as if as if these were statements about which I’m both wrong and stubbornly refuse to engage you. That kind of behavior does not a skeptic make (at least among philosophers, I’ll let you judge with respect to your own field); what it does make in my own view, I think it might be violative of the rules to say. You can take official notice of that too–right along with my “condescension.”
Anyhow, whatever the title of this site may be, I’ve got better things to do than imitate Cleese for your enjoyment.
If you insist on starting with a representationalist assumption, then it is no surprise that you are confused by direct perception.
What representationalist assumption?
The conversation will go a lot more smoothly if you augment your assertions with supporting arguments.
Basing perception on a retinal image.
If it were done that way, you would always see motion, and you would mostly see a blurry world.
How is that a “representationalist assumption”? Even direct perceptionists (with the exception of you, possibly) agree that the eye focuses images on the retina.
walto,
I like to argue when someone writes something that I disagree with. You’ve done plenty of that, as I’ve demonstrated.
Exactly, which is why I wrote this:
walto:
Your question was:
You claimed:
I answered the question before you even asked it. Not only that, but you actually quoted my answer in the same comment in which you asked the question! I wrote:
How many times do I have to answer a question (and be quoted by you) before you’ll acknowledge the answer?
I haven’t accused you of refusing to engage. I have refuted your claim that I am being pointlessly argumentative.
If you write something I disagree with, why shouldn’t I say so? How do you think things are supposed to work at The Skeptical Zone? Is skepticism something that applies only to others, never to walto? Why should your claims be exempt from criticism?
Duly noted. I’ll file “petulance” next to “unwarranted condescension” and “extreme sensitivity to criticism.”
Your Cleese imitation needs some work. 🙂
“I have refuted your claim that I am being pointlessly argumentative.”
Love that. Sums up the whole post.
Exactly. There is a distinction between being argumentative and being pointlessly argumentative.
Do you claim otherwise?
I’m too busy dealing with my shame at having been refuted so stupendously (and non-pointlessly!) to contemplate that (most subtle) distinction at present.
As you see, I’m not only condescending, petulant, thin-skinned, a bad Cleese imitator, etc. etc., but also full of shame at present. One total refutation per month is about all can deal with. Even of any (i.e., the pointless) kind.
Anyhow, I think everybody will have now been convinced that it’s not just a matter of you liking to argue.
Gibson thought that idea was contradicted by the movement of eyes in saccades.
walto,
Extra check mark next to “extreme sensitivity to criticism”.
The people who do best at TSZ are those who take responsibility for their statements. When someone expresses disagreement, they either respond with a counterargument or accept the criticism.
Others complain that they’ve been wronged when someone disagrees with them. Those folks tend not to do so well at TSZ.
You type it in. You click “Post Comment”. No one is forcing you to do that. Your comments are your responsibility. If they’re right, you take the credit. If they’re wrong, or poorly expressed, you take the blame. Just like everyone else.
Richardthughes calls it “putting on your big-boy pants”, though of course it applies to “boys” and “girls” alike.
Neil,
Fully taking saccades into account, I find it hard to believe that anyone would argue that the eye doesn’t focus images on the retina.
Do you have a supporting Gibson quotation?
Oh no!! My big boy pants are all wet now too! On top of all the refutations and non-pointless arguments and everything!
Neil,
Besides looking up a supporting Gibson quote, don’t forget to answer my question.
keiths,
I am not sure that continuous motion even exists. For humans anyway, continuous motion is equivalent to 30-60 frames per second as that’s the highest rate of change we can perceive. And it seems intuitive to me (but also related to Zeno’s paradoxes) that continuous motion, irregardless of human perception, is a logical impossibility. Things do change position, but do not pass through an infinite number of points in finite time while doing so, as continuous motion would seem to require.
JT,
For perceptual purposes, continuous motion just means that adjacent photoreceptors are stimulated in sequence as the image sweeps across them. Whether space and time are ultimately discrete is irrelevant, because the granularity and response time of the photoreceptors is so coarse by comparison.
The important distinction is between continuous motion (as described above) and the kind of “motion” exhibited by the motion illusions I cited. In the latter, an object appears in a particular location. It then disappears, and an identical-looking object appears in another location, some distance away from the first location.
The image doesn’t sweep across the photoreceptors in between those two locations, so motion cannot be directly perceived. It is inferred instead, and the implicit logic behind the inference goes something like this:
1. An object appeared at location A.
2. It disappeared, and now I see an identical-looking object at nearby location B.
3. They’re probably the same object, since objects tend not to poof in and out of existence.
4. That means the object probably moved from A to B.
Of course, I’m not suggesting that there’s a general-purpose inference engine having these “thoughts”, but rather that there is a specialized piece of neural hardware, shaped by evolution, that carries out the inference preconsciously.
That would be a waste of time. You don’t actually care what Gibson said.
That would require a lot of brain science research. It probably won’t be settled in my lifetime.
As a teenager, I rode a motorcycle. The speedometer has a balance wheel (similar to what is in a clock). It gave the speed as the distance travelled per unit of time. You could see the speedometer need jump a little at the end of each time interval. It was a pretty accurate speedometer.
Change of position over time is a standard way of getting information about motion. I have no idea why you would think otherwise.
keiths, to Neil:
Neil:
keiths:
Neil:
You couldn’t come up with a supporting quote, could you?
I’m not surprised. I think Gibson was wrong, but he wasn’t stupid.
Neil:
Neil:
keiths:
Neil:
I see. So you have no idea how the motion illusions work, yet you confidently announce that they are “fully consistent with direct perception”.
That’s pitiful, Neil, especially coming from someone who writes things like this:
Neil,
There is no “change of position over time” in the motion illusions we’ve been discussing.
Here’s how I described it to JT:
I don’t own any of his books, and it is some distance to the nearest university library.
I’ll note that I have not denied that there could be said to be an image on the retina. It’s a matter of whether that’s purposeful, as your assertions imply, or merely a side effect of how the eye operates. The image, such as it is, will have a lot chromatic aberration and spherical aberration. And it will be in motion, due to saccades, so motion in that image is useless for determining motion.
I am not repeatedly asserting that you are wrong. I am not repeatedly asserting that I have evidence that refutes your view. I’m quite aware that my position is opinion. You seem unaware that you position is only opinion.
That’s an apparent change of position over time. It seems unsurprising that something built to detect change in position over time would be triggered.
Neil,
Why do you keep digging the hole deeper? Are you a masochist?
keiths:
Neil:
Neil, later:
You’d like us to believe that you cited Gibson in response to my question, but forgot to mention that you disagreed with the view you were attributing to him?
What about the last illusion where there is no change in position at all. The dot simply disappears, yet we perceive it as scurrying behind the box to its right.
I just saw it disappear. I have no idea what others see.
JT, to Neil:
Neil:
I doubt that, but I’ll humor you. Others (including me) perceive what JT described: the dot appears to move behind the box, when in reality it has simply disappeared. Why do we perceive motion when the actual stimulus just shows a disappearing dot?
It can easily be explained in inferential terms. The surrounding dots are inferred to be in motion. Then two further inferences happen: 1) the central dot is inferred to be moving in unison with the surrounding dots, and the movement places it at the same location as the box; and 2) the dot is no longer seen, so it is inferred as being behind the box. It makes perfect sense, it fits the data, and it’s an example of a sophisticated chain of perceptual inference — the kind you say never happens.
How do you explain it? You’ve said that my examples are “fully consistent with direct perception”. If so, then show us.
You wouldn’t want to be tarred by your own brush, would you?
I think you have both been ignoring (or at least failing to cite) more than a century of experimental work on the physiology of perception. Including work demonstrating that the retina is part of the brain and not at all passive. The retina can simply refuse to be stimulated. It is not a passive camera.
petrushka,
Have you been following the debate? I haven’t claimed that the retina is “a passive camera”, and neither has Neil, as far as I can tell.
I’ll let Neil speak for himself, but is there something I’ve written that led you to that conclusion?
Obviously I haven’t been following the debate. I’ve been reading it, but haven’t been following it.
Judging by the lack of progress, I’d say the same appears to be true of all participants.
I seem to lack the brain component necessary to follow this kind of discussion.
But since everyone seems to be talking past everyone else, I had hoped there would be some attempt to shift gears and reach some mutual understanding of terms.
petrushka,
That would be a mistake.
We have reached such an understanding. We’re in agreement that for perception to be direct, there must be an absence of intermediate inferences, representations, and models.
I have argued (in detail) that the motion illusions cannot be explained without recourse to inference. Still waiting for Neil to show that they can, since they are “fully consistent with direct perception”, in his words.