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Allan W. Snyder and Mandy Thomas
Centre for the Mind
Australian National University
Canberra, Australia
Certain autistic children whose linguistic ability
is virtually non-existent can draw natural scenes from memory
with astonishing accuracy. In particular their drawings display
convincing perspective as illustrated in Figure 1. In contrast,
normal children of the same preschool age-group and even untrained
adults draw primitive schematics or symbols of objects which they
can verbally identify. These are usually conceptual outlines devoid
of detail as shown in Figure 2. We argue here that the difference
between autistic child artists and normal individuals is that
autistic artists make no assumptions about what is to be seen
in their environment. They have not formed mental representations
of what is significant and consequently perceive all details as
equally important. Equivalently, they do not impose visual or
linguistic schema - a process that we believe is necessary for
rapid conceptualisation in a dynamic existence, especially when
the information presented to the eye is incomplete.
Naturalistic drawing skills are not essential
to survival, but it is nonethless a surprising fact that normal
individuals can not draw unless they are taught the tricks and
schema to do so or equivalently unless they learn these tricks
by trial and error or by using drawing aids. The reason why this
is so unexpected is that our brains obviously possess all the
information required to draw, but we are unaware of this. For
example, our brains perform the necessary calculations for us
to recognize and label objects and to recall sufficient detail
to perceive subtle changes in familiar scenes. Indeed, it is clear
that human vision itself reveals the artist's touch , yet we are
not consciously aware of how our brain does so. This fact has
frequently intrigued philosophers and historians of art. For example,
Gombrich says, 'One thing stands out from this story and demands
a psychological explanation. It is that this imitation of visual
reality must be very complex and indeed a very elusive affair,
for why should it otherwise have taken so many generations of
gifted painters to learn its tricks?' One trick, pertinent to
our story, is to view the subject from an unconventional perspective,
that is, one which has not been overlearned.
Why is it then that we cannot draw natural scenes,
not only from our rich visual memories but even when we are also
confronted with a stationary landscape? Indeed, teachers of art
admonish us for not observing what lies before our very eyes.
Children especially draw not what they 'see' but, rather, their
own internalised schema for objects, schema which are surprisingly
invariant across cultures. There is an appealing answer to this
enigma. Our drawing difficulties may well be the by-product of
strategies which have evolved to efficiently utilise a finite
brain for rapid decision-making, particularly, as so often happens,
when the information is incomplete.
Indeed, it has been argued that scenes presented
to the eye are not an unlimited succession of surprises, but rather
conform to certain patterns. Thus, cognition would become more
rapid and efficient if the brain had expectations about what is
to be seen, and it would be plausible for these expectations to
become incorporated into perceptual mechanisms. Now natural scenes,
as distinguished from the infinity of contrived scenes, are composed
of discrete objects. We would expect then that objects of particular
importance or familiarity be granted privileged mental representations.
Such visual representations are acquired through the process of
overlearning as are the complex thought processes required for
expertise within our niche, including fluency in language, complex
social skills and even driving a car. Because all naturally occuring
objects share common attributes, those studied through the ages
by artists, we might also expect these more intrinisic properties
to be structured into visual processing. This has been discussed
at length elsewhere. So, in summary, we hypothesize that the
brain has mental representations that embody the salient or ecologically
significant aspects of the environment. These allow for automatic
complex actions.
We can make some revealing predictions about
a brain that accelerates its formulation of the percept by incorporating
expectations about familiar or important objects. Firstly, this
particular strategy of visual processing would reveal itself by
falling prey to illusions or prejudices in contrived or unnatural
situations. Indeed, errors in cognition are ubiquitous. Even assumptions
about the more intrinsic attributes in common with all objects
can cause illusions, as discussed fully elsewhere. Secondly, and
most importantly, it is the object labels or symbolic identifications
which are of ultimate importance, so we need not be aware of all
(and thus unable to draw) the attributes and characteristics which
are processed by the brain to formulate the label. For example,
we are not consciously aware of why one face is recognizable over
another, nor how we derive shape from shading, perspective from
gradients of texture, size invariance with distance, etc. This
strategy of visual processing is mirrored also in early linguistic
skills whereby children tend to linguistically label objects long
before they are conscious of the semantic nuances which differentiate
one object from another.
If the brain places emphasis upon expectations
acquired through mental representation that is suggested above
and, in particular, reports only the ecological aspects of objects
to our conscience, then we have advanced a long way in explaining
our innate difficulty in drawing. But this raises a fascinating
question. What are the characteristics of a brain that makes no
assumption about what is to be seen? Equivalently, what would
it be like if our minds did not possess mental representation
that embody expectations? Suppose, instead that we were to make
no assumptions whatsoever.
A conceivable answer, we suggest, comes from
the study of autistic children. Autism is believed to be a developmental
disorder and thus its behavioural ramifications vary with age.
In its purest form, autistic individuals confront life as a series
of surprises. A common feature of autistic children is an impoverished
linguistic ability, for example less than ten words by age four.
They appear to give attention to parts at the expense of the whole.
Indeed, they can be very good at spotting abstract shapes embedded
in a coherent pattern but have an inability to integrate or to
make links. They observe the world without interpretation. They
cannot work out what others think. Put simply, autistic children
do not have expectations about this world and its dynamic interactions.
Their mental representations have yet to be crystalized.
Figure 1. Autistic child's drawing at about three and
a half years. (taken from Reference 1.)
Now recall our arguments above which explain
the difficulty of drawing as due to a by-product of our assumptions
and expectations about the objects in our visual environment.
Such expectations are incorporated by our mental representations.
If this is true, then it would appear that natural drawing skills
could potentially be found among autistic children because they
apparently do not make such assumptions. Figure 1 shows that,
this is the case. This particular drawing was performed from memory
by Nadia, a child of about three and a half. It is initiated at
a seemingly arbitrary position and executed quickly without hesitation.
No attempt is made to fit such drawings onto a page, they can
end abruptly at the border. Furthermore, as the linguistic abilities
of this (and other) autistic artist improved, her naturalistic
drawing skills deteriorated. All of this is consistent with the
view that autistic preschool children can draw because they lack
fixed mental representations. Indeed, there is evidence that Nadia’s
mental images are occasionally mixed, allowing for subjects to
be drawn from different angles. Although rare, similar drawings
are characteristic of other preschool autistic child artists.
The rarity is due in part to the fact that autism often exists
in parallel with other mental disorders and these mitigate against
drawing. Autistic preschool children are also notoriously difficult
to motivate. They do not draw on request. Finally, no normal
preschool child has been known to draw naturalistically, figure
2 being representative of their drawings. Autism is apparently
a necessary condition for a preschool child to draw an accurate
detail of natural scenes.
Figure 2. Representative drawings of normal children,
each at age four years and two months. (Emma and Teneal, Parents
on Campus Preschool).
Some older autistic children (with language ability)
have also been known to have exceptional drawing skills, but so
do many normal children of the same age. In fact, childrens drawings
after age 6 are like adults in that they are all governed to a
degree by conventions. Accordingly, we have deliberately restricted
our study to younger preschool children.
We have hypothesized that the brain has mental
representations which embody the salient or ecologically significant
aspects of the environment. As an example, normal preschool children
draw rather schematic or symbolic representations, stripped of;
shape from shading, perspective from gradients of texture, size
invariance with distance, etc. These sketches convey highly imposed
or internalised meanings. They, along with early linguistic skills,
are consistent with a mind that is conscious of the objects themselves
and not the object characteristics processed by the brain to formulate
the label or symbolic identification. All of this fits neatly
into a strategy for making rapid decisions, particularly when
confronted with incomplete information. Such strategies mitigate
against naturalistic drawing. In contrast, autistic preschool
children do not appear to impose expectations on their world and
consequently, to them, every detail is of equal importance. Consequently,
they are sometimes capable of curious skills such as drawing naturalistically,
but at the cost of being able to make rapid decisions. Finally,
our discussion may give telling insight into machine vision. A
machine that possesses complete information about the world is
useless unless assumptions about what is deemed important are
built in.
Acknowledgements: We much appreciate penetrating
discussions with Max Coltheart, Ian Gold, D. John Mitchell and
Gerrard Vassiliou.
References
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