What is striking is the huge amount of brain contributing to vision, giving immense added value to the images of the eyes. Where does this extra richness for vision come from? By some authorities it is simply denied-they see perception as passive acceptance of what is out there, as a window facing the world. But this does not begin to explain how we see objects from the sketchy images of the eyes, even from sparse lines and crude dots of seemingly inadequate pictures. In ideal conditions, object perception is far richer than any possible images in the eyes. The added value must come from dynamic brain processes, employing knowledge stored from the past, to see the present and predict the immediate future. Prediction has immense survival value. It not only makes fast games possible in spite of the physiological signal delays from eye to brain, and brain to hand. Anticipating dangers and potential rewards is essential for survival¬made possible by buying time from seeing objects distant in space. (Gregory, 1997, p. 2).I am assuming that EPists are among the "authorities" here. I think the perception as passive idea comes from the talk of direct pickup; there is no activity of inference or computing. For EPists the activity of perception is moving the eyes and body around, but that thereafter the visual system just lets the information seep in.
For Gregory, there is the activity of moving the eyes and body (I assume he's ok with the movements of the body. The eye he discusses briefly (p. 44f)). The interesting perceptual activity for Gregory, however, is in the brain.
For EPists the activity of perception is moving the eyes and body around, but that thereafter the visual system just lets the information seep in.
ReplyDeleteHardly. The active pickup of information is a critical component, often the mechanism that creates the next information to be detected. Information doesn't seep in, it is actively discriminated.
I think I've read EPists taking exception to this passivity charge, but it comes down to what this "active pickup" and "active discrimination" amounts to. On the one hand, it's not stuff like computation or inference happening in the brain, but, now, on the other, you don't want to say that it is just moving the eyes and body. Ok, so what is it? What is this "active pickup" of which you speak? What constitutes this "active pickup"?
ReplyDeleteHere is what I think is going on. "Active" is a "higher status" proposal than is "passive", much as "dynamic" is "higher status" than "static". So, psychologists like to say that their view is active and dynamic, where the other view is passive and static. But, following Gregory's cue, I'm pressing for what this activity and dynamism comes to in EP.
ReplyDeleteI think it's also possible that EPists are making some sort of conceptual claim what they say that perception is active. It's not just that perception involves or is constituted by moving around. Instead, perception is active in the sense that you are doing something when you perceive, in just the way that you are doing something when you believe, doing something when you are feeling an emotion. Maybe it is this sense in which directly picking up information is doing something-is active.
ReplyDeleteWhen, in the opening passages of Action in Perception Noe claims that perceiving is doing something, that kind of leave me cold. Since I see a number of senses in which this must be right, but I'm not really sure who in their right mind would want to deny that perception is passive. This would have to take on a kind of particular meaning, which it might in the context of perception being direct pick up.
Active doesn't just mean moving around. It means you have to select which information to detect at different times, you have to acquire the ability to differentiate that information from the rich array, etc. I'm not simply receiving information: I go looking for it, I create some of it by virtue of my going looking for it, finding some of it is what then allows me to move so as to find the next bit, and so on.
ReplyDeleteInformation pickup is an active, dynamic process because it entails effort and feeds back into the next round of that effort.
We (perceptionists) all need our theories to have these features, we just put the responsibilities in different places. Gregory puts it all in the brain, Gibson distributes it over time, space and organism behaviour. But because we all know we need these features in our theories, Gregory trying to say Gibson (assuming he's the target) is merely passive is a low blow that actually misses the mark. It's not actually a point of difference he can use to support his account.
So, what I am trying to do is make some sense of what Gregory is claiming. When he says that some authorities see perception as passive acceptance, I think he is talking about seeing perception as non-computational. And you think he is not talking about anything. It's all just rubbish.
ReplyDeleteBut, as I will post a time or two in the coming days, there are vision scientists who charge orthodoxy with being "passivists" about vision.
If he's making a big thing about the claim that some people think vision isn't active in some sense then he's fighting a straw man. If he's claiming Gibson thinks perception is passive reception then he's fighting a straw man who doesn't even exist.
ReplyDeleteHe's just talking about the familiar claim that EPists don't believe in assumptions, inference, etc.
ReplyDeleteWhat is striking is the huge amount of brain contributing to vision, giving immense added value to the images of the eyes. Where does this extra richness for vision come from? By some authorities it is simply denied-they see perception as passive acceptance of what is out there, as a window facing the world.
It's a stupid way to express it, but ok, whatever :)
ReplyDelete