Perceptual Transparency and Sinha’s Observations

In 1976, when I delivered the John Locke Lectures at Oxford, I often spent time with Peter Strawson, and one day at lunch he made a remark I have never been able to forget. He said, "Surely half the pleasure of life is sardonic comment on the passing show".  This blog is devoted to comments, not all of them sardonic, on the passing philosophical show.

Hilary Putnam

Pawan Sinha, who with Richard Held carried out the observations on children in India who had been blind from birth and subsequently (at ages ranging from 8 to 17) had their vision restored with the aid of corneal implants - experiments that I described in the previous post (as well as in my post of August 27, 2014) has shared the following observations with Held and myself:

“     Regarding Prof. Putnam's question about the subjective reports of children prior to the establishment of cross-modal connections, I think the answer is rather unremarkable. The children do have a sense of 'objectness' in the visual domain. They have difficulties parsing an image into distinct objects, but they do seem to understand the notion of objecthood. For instance, after their surgery, one can wiggle fingers in front of their eyes and ask how many things they see. If they are familiar with counting, they can respond correctly. Similarly, one can ask them to enumerate the number of items scattered on a plain background. I think some of this sense of objectness has its genesis in the fact that the children have light perception prior to surgery. This also means that they can see vague shadows when they pass their hands over their eyes in bright sunlight. Even this very rudimentary stimulation may suffice to help them associate the notion of objectness derived from proprioception and touch with one in vision.”

This further information is fascinating, but in no way incompatible with my claim that the Held-Sinha observations show that “transparency” is not innate or intrinsic to visual experiences. To explain why it isn’t incompatible, let me describe the issue as it now arises in the philosophy of visual perception. First. a couple of words about what the debate isn’t about. The transparency thesis is a thesis about all visual experiences. That is why Molyneux patients (as I shall call them) and Held’s famous kittens are highly relevant. The key claim (of, e.g., “representationalists” like Tye) is that transparency (or “diaphanousness”) is not just a normal feature of (mature, human) visual perception, which is uncontroversial, but that it is an essential  feature of all visual experience, i.e. there couldn’t be a visual experience which lacked it. The defenders of  “perceptual transparency” are transparency essentialists. So it is enough to show that some visual experiences are not “transparent” to refute their position.

Secondly, the debate is not about whether one could have a visual experience without having “the notion of objectness” – if I understand that question, it would seem to be about whether perception is conceptualized, which is a different issue[1]. Moreover, even if the defenders of transparency were claiming that subjects conceive of what they see as objects, in the logical sense of object, in which anything one can count (including shadows) is an object”,  that sense of object is much too weak to capture the idea that perception is “transparent”.

So, not to keep you waiting, I want to come to what “transparency” is supposed to be, and finally to a related question, whether what Sinha reports is or is not in conflict with what Ostrovsky et al reported[2].

What “transparency” is supposed to be

The observation that visual experiences are normally experienced as transparent goes back to G.E. Moore (who was not a transparency-essentialist, however). The following paragraph from Moore’s Refutation of Idealism has been widely quoted:

“…when we refer to introspection and try to discover what the sensation of blue is, it is very easy to suppose that we have before us only a single term. The term blue is easy enough to distinguish, but the other element which I have called consciousness — that which sensation of blue has in common with the sensation of green — is extremely difficult to fix. That many people fail to distinguish it at all is sufficiently shown by the fact that there are materialists. And, in general, that which makes the sensation of blue a mental fact seems to escape us: it seems, if I may use a metaphor, to be transparent — we look through it and see nothing but the blue.”

Similarly, in  Seeing Things As They Are: A Theory of Perception (p.188), John Searle explains transparency thus:

“The veridical case of the perception reaches right up to the object itself. We see right through to the object, we do not see any intermediate entities, and the description of our perception is precisely a description of the object in the external world. If you try to describe the experience, you end up describing the objects and states of affairs that you perceive.”

Speaking for myself, I think that what it is to see something as “an object in the external world” is to see it as possessing what Gibson called “affordances”, e.g., as something I can touch by stretching out my hand so, or, alternatively, as something “too far away to touch”. If that is what transparency means, then Held’s observations (both on kittens and on Molyneux patients) shows that transparency is learned and not innate or intrinsic to the visual sensations themselves. That is why I think that the fact that cross-modal connections are learned already refutes transparency. “Out-thereness” is cross-modal. But even if there is a sense in which a purely visual sensation, unassociated with any haptic elements, could look “external”), if even some subjects satisfy the description of Ostrovsky et al, even part of the time, viz. “they pointed to regions of different hues and luminances as distinct objects. This approach greatly oversegmented the images and partitioned them into meaningless regions, which would be unstable across different views and uninformative regarding object identity”, then in those situations even if they think of those regions as “objects”, they don't see them as external  objects in any meaningful sense of “external”. If even visual sensation of the sort these investigators describe count as experiences of “external objects”, what content does “external” have?

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[1] See Hilla Jacobson and Hilary Putnam, “Against Perceptual Conceptualism”, International Journal of Philosophical Studies (accepted). 

[2] Here is a description of the subjects studied by Ostrovsky et al:

“subjects’ responses were driven by low-level image attributes; [when asked to point to objects] they pointed to regions of different hues and luminances as distinct objects. This approach greatly oversegmented the images and partitioned them into meaningless regions, which would be unstable across different views and uninformative regarding object identity. A robust object representation is difficult to construct on the basis of such fragments”  (Ostrovsky, Y., et al. 2009. “Visual parsing after recovery from blindness”. Psychological Science 20, 1484-1491. 

Perceptual transparency (repeated as background to next post)

In 1976, when I delivered the John Locke Lectures at Oxford, I often spent time with Peter Strawson, and one day at lunch he made a remark I have never been able to forget. He said, "Surely half the pleasure of life is sardonic comment on the passing show".  This blog is devoted to comments, not all of them sardonic, on the passing philosophical show.

Hilary Putnam

Back in August (August 27, 2014, to be exact), my post included a description (which follows) of two sets of experiments by Richard Held of MIT, who was my colleague when I was Professor of Philosophy of Science there from 1961 to 1965. I argued, and would still argue, that those experiments show that what is called the “transparency” of our visual experiences is learned and not innate or intrinsic (not part of their “essence”, as it were). Some months later Held transmitted to me a further description of the second set of experiments (involving children who had been blind from birth) by Pawan Sinha, who collaborated with Held in this research. In this post, I will simply repeat the earlier description so my readers won’t have to scroll down all the way to the August 27 post. In the next post I will give the further description and discuss whether it requires any modifications in my argument.

Held’s experiments (1)

There is strong experimental evidence that in certain cases, described by Richard Held in two different series of experiments many years apart, some non-human mammals and even some humans do not visually perceive colors and shapes as “out there”. I conclude that “transparency” is (normally) the result of early learning (but, contrary to Block’s view, mentioned in my previous post, not something we can override if we try and we know how to do it. At least I see no evidence for this claim.) The first visual experiences of many mammals, including both cats and humans, are not experienced by those organisms as properties of surfaces “out there”. “Out-thereness”, recognition of things as having locations in places accessible to both sight and touch, requires that the correlations between visual space and sensorimotor (tactile, or “haptic”) space be learned. The disposition to learn such correlations quickly may well have been selected for in the evolutionary history of our visual and haptic systems, but some hours or days of learning are still needed. Here is some background.

In 1963, when Richard Held and I were colleagues at MIT, he showed me the following experiment that he and Alan Hein performed[2]: two kittens were placed in baskets that were at the opposite ends of a pole that was free to rotate around a vertical axle[3]. One basket had holes that permitted the kitten in that basket, kitten A, to push against the floor and thus to determine how the basket would move, at least to a limited extent. Kitten B’s basket had no holes; willy nilly, kitten B experienced spatial motion when kitten A moved – the mirror image of kitten A’s spatial motion, in fact - but no sensorimotor feedback. When kitten B was taken out of its basket, it had no recognition of any sensorimotor affordances at all. If one poked a finger towards its eyes, it stuck out its paws (an innate reflex), but not in the direction of the approaching finger. If it were put near the edge of the table, it would fall off (or would have fallen if there were not something to catch it) as often as not. But when Kitten A was taken out, it was able to position its paws in front of the threatening finger, it never walked off the edge of the table, etc. The results strongly suggest that the kitten that had not learned those correlations did not see the visual data it experienced as “out there”, and so the phenomenal aspects of its visual experiences were not transparent.

Held’s experiments (2)

In 1688 William Molyneux sent a message to the philosopher John Locke asking: “Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere of the same metal ... Suppose then the cube and sphere placed on a table, and the blind man be made to see: query, whether by his sight, before he touched them he could now distinguish and tell which is the globe, which the cube ...?”[4]

In 2011 a team of researchers including Held and led by Pawan Sinha of MIT, published a negative answer to Molyneux’s question.[5] Similar results were reported earlier by a group referred to by Held in “Visual-Haptic Mapping and the Origin of Crossmodal Identity”[6]. The research involved studying youngsters who had been blind from birth, after they had lenses surgically implanted under the auspices of Project Prakash in India. Here is  the Abstract of “Visual-Haptic Mapping”:

“We found that the congenitally blind person who gains sight initially fails to identify seen objects with their felt versions: a negative answer to the Molyneux question. However, s(he) succeeds in doing so after a few days of sight. We argue that this rapid learning resembles that of adaptation to rearrangement in which the experimentally produced separations of seen and felt perceptions of objects are rapidly reunited by the process called capture. Moreover, the original ability to identify objects across modalities by the neonate may be assured by the same process.”

—And here is a description of the subjects studied by Ostrovsky et al:

“subjects’ responses were driven by low-level image attributes; [when asked to point to objects] they pointed to regions of different hues and luminances as distinct objects. This approach greatly oversegmented the images and partitioned them into meaningless regions, which would be unstable across different views and uninformative regarding object identity. A robust object representation is difficult to construct on the basis of such fragments”  (Ostrovsky, Y., et al. 2009. “Visual parsing after recovery from blindness”. Psychological Science 20, 1484-1491. 

In sum, these subjects’ visual experiences were anything but “transparent” to them. The representational content of visual experiences is something we learn to recognize. It is not intrinsic, and a fortiori not identical with their phenomenal character.

Husserl thought of Twin Earth! 

In 1976, when I delivered the John Locke Lectures at Oxford, I often spent time with Peter Strawson, and one day at lunch he made a remark I have never been able to forget. He said, "Surely half the pleasure of life is sardonic comment on the passing show".  This blog is devoted to comments, not all of them sardonic, on the passing philosophical show.

Hilary Putnam

Dagfinn Føllesdal informs me that Husserl had the Twin Earth thought experiment in mind in 1911!

Husserl wrote,

“But how is it, if on two celestial bodies two people in surroundings that seem to be totally similar, conceive of “the same” objects and adjust their utterances accordingly? Does not the “this” in these two cases have a different meaning?

It is some comfort, however, that I could not have know this in 1972, the year in which I wrote the first complete draft of “The Meaning of ‘Meaning’”, for, as Føllesdal writes[1],

Husserl’s manuscript was printed in 1987, long after Putnam had put forth his twin earth example.  Before then it was known only to a few Husserl specialists, and the examples had never been mentioned in the philosophical discussion.  So Putnam got the idea independently.

Whew!

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[1] Dagfinn Føllesdal, “Husserl and Putnam on Twin Earth”, forthcoming in Themes from Putnam, Michael Frauchiger (ed.), Ontos.