Lecturer's Précis - The Molyneux Question

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First published online 09:00 BST 20th September 2006, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 18:00 14th January 2010

 

 

1 - The Nature-Nurture Debate in Perception

The nature-nurture debate in perception is all about whether we are born able to perceive or whether we have to learn how to do it. What has come to be known as the Molyneux Question sums up the entire issue. This is how it was posed of the philosopher John Locke in the late 17th century .....

 

"..... To which purpose I shall here insert a problem of that very ingenious and studious promoter of real knowledge, the learned and worthy Mr. Molyneux, which he has pleased to send me in a letter some months since: and it is this: '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, and nighly of the same bigness, so as to tell, when he felt one and the other, which is the cube, which the sphere. Suppose then the cube and sphere placed on a table, and the blind man to 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?' To which the acute and judicious proposer answers: 'Not. For though he has obtained the experience of how a globe, how a cube, affects his touch; yet he has not yet attained the experience that what affects his touch so or so must affect his sight so or so; or that a protuberant angle in the cube, that pressed his hand unequally, shall appear to his eye as it does in the cube.' I agree with this thinking gentleman, whom I am proud to call my friend, in his answer to this his problem; and am of opinion that the blind man, at first sight, would not be able with certainty to say which was the globe, which the cube, whilst he only saw them; though he could unerringly name them by his touch ....." (Locke, 1690, Book II, IX.8; emphasis added).

 

In agreeing that the newly sighted blind man would not be immediately capable of visual perception, Locke was arguing that this ability needs to be learned empirically - that is to say from one's experience of the world. No prior experience, no perception; as simple as that. Humans are born with effectively an empty mind and their experiences gradually develop it and fill it up. Locke called this empty mind upon which experience "writes" a tabula rasa (Latin = "blank slate"), and this type of explanation subsequently became known as empiricism.

 

Key Concept - "British Empiricism": School of philosophy derived from 17th and 18th century thinkers such as John Locke and Bishop Berkeley, and leaning very heavily towards the nurture side of the nature-nurture debate. Locke was famous for accurately predicting the outcome of the Molyneux Question (see above), and Berkeley for philosophical conundrums such as the possibility (probability?) that what person A experiences as a particular perceptual quality (say "redness") need not match person B's experiences, even for an identical stimulus. If asked what mental abilities we are born with, an extreme empiricist would answer "the ability to acquire knowledge", whereas the extreme nativist would answer "everything"; the truth - as always - probably lies somewhere in between. In describing the infant's world as a "great blooming, buzzing confusion", William James (1890) was taking a distinctly empiricist position.

 

As luck would have it, the Molyneux Question was put quite quickly to the test once it became possible for sufferers from cataracts to be cured by surgical procedure. This is because such sight-restoration patients are seeing the world for the first time. Von Senden (1932) reviewed the literature here, and found 3 oblique or poorly detailed reports in the period 1020 to 1709, and a further 41 in the period 1728 to 1931. On balance, these reports (extracts in Section 2) support the view that there is no recognition of visual pattern or depth in such patients: that is to say, that there has been no "transfer" of knowledge from tactile experience to the visual modality. There was, on the other hand, some apparent ability to distinguish colour and brightness or even to judge that two patterns were different. Von Senden's work remained relatively obscure until it was referenced by Donald Hebb in his 1949 book "The Organisation of Behaviour", and, more recently, Richard Gregory reports some rather tragic case history of newly sighted patient SB, a 52 year old male, in his 1966 book "Eye and Brain".

 

 

2 - Visual Abilities of the Newly Sighted

Here are extracts from the 41 reasonably reliable reports of sight renewal identified by Von Senden (1932/1960) in the literature between 1728 and 1931, in which were documented a total of 62 individual patients. Note that this work only became readily available in English in 1960, and that there is often a short delay between the date of the curative operation and the date of the write-up.

 

Cheselden (1 patient, 1728): This is the first significant academic report of sight renewal, and refers to a 13 year old male .....

 

"He knew not the shape of anything nor any one thing from another, however different in shape or magnitude [.....] but upon being told what things were, whose form he knew before from feeling, he would carefully observe, that he might know them again." (Cheselden, 1728, cited in Von Senden, 1960, p129 and pp182-183.)

 

Daviel (22 patients, pre-1762): Operated on 22 congenital cataract patients and reported that upon regaining their sight "not a single one [has] recognised the objects shown to him after the operation, without the use of touch, unless they have been many times shown to him and named." (Daviel, 1762, cited in Von Senden, 1960, p106.)

 

Home (2 patients, 1806): Here are comments relating to a 7 year old male .....

 

"Upon being shown a square, and asked if he could find any corners to it, the boy was very desirous of touching it. This being refused, he examined it for some time, and said at last that he had found a corner, and then readily counted the four corners of the square; and afterward, when a triangle was shown him, he counted the corners in the same way; but in doing so his eye went along the edge from corner to corner, naming them as he went along. (Home, 1807, cited in Von Senden, 1960, p118.)

 

Beer (14 patients, 1783-1813): Tested 14 patients, and concluded .....

 

"Apart from the outline, they cannot judge mathematical solids at all by eye alone; thus a sphere appears to them a circular disc, more or less illuminated at particular points. But feeling, and the direction of motion in their hands together teach them that this body also curves away backwards, and so at length they learn to recognise its shape completely ....." (Beer, 1813, cited in Von Senden, 1960, p266.)

 

Franz (1 patient, 1840): Tested an 18 year old male with a pyramid, first with one triangular face showing, and then with an edge toward him.

 

"After considering and examining it for a long time, he said that this was a very extraordinary figure; it was neither a triangle, nor a quadrangle, nor a circle; he had no idea of it, and could not describe it." (Franz, 1841, cited in Von Senden, 1960, p269.)

 

Nunneley (1 patient, pre-1855): Here are observations of a 9 year old male faced with the original Molyneux test .....

 

"..... he could at once perceive a difference in their shapes; though he could not in the least say which was the cube, and which the sphere, he saw they were not of the same figure." (Nunneley, 1858, cited in Von Senden, 1960, p107.)

 

Von Hippel (1 patient, 1874): Wrote of a 4 year old girl presented with the Molyneux test one week after her operation .....

 

"I presented her with the cube and the sphere which she had so often had in her hands before, and asked her what they were. She could neither name them correctly, nor in any way describe their form aright; indeed, I remained very doubtful whether she had actually recognised them even as distinct from one another." (Von Hippel, 1875, cited in Von Senden, 1960, p108.)

 

Dufour (1 patient, 1875): Showed a watch to his patient, a 20 year old male, and reported as follows .....

 

"'Is it a round thing or a square one?' - No answer. 'Do you know what a square is?' - He positions his two hands so that they form a pair of surfaces which make contact almost at right angles ......... 'And a circle?' - He again bends his hand round with the fingers pointing towards the wrist , and thereby produces an almost complete ring. After this fashion he therefore has some knowledge of circularity. In looking at the watch [however] he remains absolutely incapable of saying whether it is round or cornered. ...... On the following morning the same question; the same inability to answer. So I let him feel the watch. No sooner has he taken it in his hand than he immediately says 'That's round, it's a watch.'" (Dufour, 1876, cited in Von Senden, 1960, pp108-109.)

 

Fialla (6 patients, 1875-1877): Wrote of a 10 year old female operated on in 1876 .....

 

"I showed her various objects, such as coins, a glass and a spoon, but she made no answer. [I then] showed her my hand and asked her what it was; she looked long at it, without saying a word; I then took her own hand and held it before her eyes, whereupon she said with a deep sigh: 'That's my hand.' A blind person has no exact idea even of the shape of his own body; so that I first had to hold her own hand before her in order for her to recognise mine as a hand also." (Fialla, 1878, cited in Von Senden, 1960, p109.)

 

Uhthoff (1 patient, 1890): Tested recognition of a range of objects in a 7 year old male .....

 

"The confusions perpetrated by the patient in the recognition of objects, notably in the early stages of his visual studies, are naturally very numerous and in some cases strange; it may be observed in this connection that, in interpreting a new object not so far seen, he draws upon experiences he has had already, and particularly those acquired shortly before. Thus he describes a lamp with a white shade as a 'bowl', a bottle as 'glass', an egg as a 'rubber ball', a rabbit sitting on its haunches with flattened ears as a 'box', and on touching it as a 'cat' ....." (Uhthoff, 1891, cited in Von Senden, 1960, pp197-198.)

 

Augstein (1 patient, 1913): Tested a 15 year old male and found generalisation from experience with a single exemplar object to a range of physically similar objects .....

 

"It was now notable that once an object had been correctly identified by the aid of touch, it was not only easy to recognise it again, but it was always correctly identified in a great variety of sizes and shapes; so that after he had got to know scissors and knife, for example, he at once recognised the largest and smallest scissors and knives correctly." (Augstein, 1913, cited in Von Senden, 1960, p194.)

 

Mauthner (1 patient, 1879): Tested reading of letters in a 20 year old female .....

 

"I now made her write some letters on the board. She did this, though without making use of her vision, but merely as the blind do, in that she followed with the chalk the movements whereby the index finger of the left hand was likewise tracing out the form of the letter on the board beforehand. When I then first made her turn away from the board and after a few minutes pointed to one or other of the letters, she could not read them, though they had been quite legibly written by herself ....." (Mauthner, 1980, cited in Von Senden, 1960, p109.)

 

Schnabel (2 patients, 1879-1880): Wrote of a 12 year old female .....

 

"The first visual tests were carried out sixty hours after the operation. In order to make sure whether the patient had really completely forgotten how things look, I slowly passed a number of objects before the child's eyes, without asking her any questions; first my hand, then a white cloth, a glass filled with water, a watch hanging from a chain, and two large keys. The patient's face bore an expression of extreme surprise and joy, as with eyes fixed she followed the slowly moving objects. She insisted that she could see, but did not know what it was she saw, naming only the watch, whose two sides she described as yellow and white, and whose ticking she could hear." (Schnabel, 1880, cited in Von Senden, 1960, p110.)

 

And of a 5 year old male:

 

"..... was very quick in learning to recognise colours. After having once shown him a number of samples of coloured paper and told him the names of the colours, he never made a mistake in naming them, even when I only showed him the coloured sheet for a moment. [Eleven months later] he has even forgotten again a number of objects that he learnt to recognise during his first stay at the clinic. Only the knowledge of colours has been strengthened and increased." (Schnabel, 1880, cited in Von Senden, 1960, p149.)

 

Trinchinetti (2 patients, 1846): Tested distance judgement in an 11 year old male and a 10 year old female. Here is what happened when he held an orange up in front of their faces .....

 

"..... when I told him to take it, he raised his hand so that it almost touched his eye, and there clenched his fist, which he was astonished to find empty. When I told him to repeat the experiment, he stretched out a hand at a distance of several inches from his eye and here renewed his attempt to grasp the orange.  I then decided at once to make the same experiment with the girl; she too at first attempted to grasp the fruit with her hand quite close to her eye; but immediately on perceiving her error she stretched out her forefinger and directed it slowly in a straight line from her eye towards the orange, until she was able to touch it." (Trinchinetti, 1847, cited in Von Senden, 1960, p227.)

 

Seydel (1 patient, 1902): Found active interest in visual inspection in a 10 year old female, about 5 weeks after her operation .....

 

"She now recognised for the first time two objects which had not previously been taught to her, but which she had chanced to see on the station. From this we were led to conclude that she was already undertaking her own visual studies, and the difference in her attitude also confirmed this opinion: during the pauses she took a look at some particularly striking object not yet known to her, inspecting it with interest from every angle, and eventually checking her visual impressions by handling it." (Seydel, 1902, cited in Von Senden, 1960, p199.)

 

Anonymous (1 patient, 1928): Tested the perception of such visually confusing phenomena as sunbeams and shadows in an 18 year old female .....

 

"Approaching carefully in order not to bark her shins, she reached down to feel the thing but her hand passed through it. Puzzled, she walked around and tried to feel it from the other side. Her new eyes said that there was something there but her reliable 18-year-old hand told her that there was nothing. She finally discovered that it was a sunbeam." (Anon, 1928, cited in Von Senden, 1960, p200.)

 

"The first time she was handed photographs and paintings she asked: 'Why do they put those dark marks all over them?' 'Those aren't marks,' her mother explained, 'those are shadows. That is one of the ways the eye knows that things have shape. If it were not for shadows many things would look flat.' 'Well, that's how things do look,' Joan answered. 'Everything looks flat with dark patches.'" (Anon, 1928, cited in Von Senden, 1960, p211.)

 

Hirschberg (1 patient, 1874): Tested the development of perspective cues in a 7 year old male .....

 

"The general principles of perspective began to dawn upon him. When I stood some three feet away from him in front of a chair, which was half hidden by my body, he said very decidedly that he could see that the chair was standing behind me, and seemed to perceive that the remoter object was partially obscured by the nearer one." (Hirschberg, 1875, cited in Von Senden, 1960, p256.)

 

Von Senden's own conclusions are summarised as follows .....

 

A)   Of "the spatiality of tactual impressions" (pp289-290) .....

 

"(1)         The congenitally blind man has no a priori awareness of space.

(2)          He does not acquire it either from sensations of localisation on his skin, or from kinaesthetic sensations accompanying the movement of his limbs, or from concomitant muscular sensations."

 

B)   Of "spatial vision" (pp306-308) .....

 

"(1)         The impressions specific to vision are brightness and colour. Vision is at first purely phenomenal in character.

(2)          The perception of colours is inseparable from that of surfaces []

(3)          Thus visual space is neither a sensation on its own account, nor a qualitative idea, nor the product of a synthesis of impressions, nor an intellectual abstraction; it is a 'form of intuition', given along with the sensory content in every act of vision, and inseparable from this.

(4)          Once the colour-patches have been consciously identified as visual objects, they also begin to be consciously located in space; gross differences in depth are perceived, and practice leads to a developing estimation of depth.

(5)          Objective space is [] acquired from subjective space, by grasping the positional relations of visual objects to one another.

(6)          Both spaces, subjective and objective, are progressively enlarged, the subjective first []

(7)          [The] stimuli impinging on the visual organ from an objective shape merely occasion the act of perception as such, but do not determine its outcome. The idea of shape is [] the outcome of a process of conscious interpretation in time."

 

C)   In general (pp309-311) .....

 

"We have been led to conclude that by tactual perception alone the patient is unable to acquire an awareness of space, and that this is solely dependent on visual perception."

 

3 - References

 

See the Master References List

 

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