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 [2.0 - copyright] 09:00 BST 5th July
2018.
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
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Master References List
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