Elizabeth Johnston, Investigating Minds, 12/1/97
Lecture 21: Autism
What is Autism?
Autism is a pervasive developmental disorder that was first termed "infantile
autism" by an American physician, Leo Kanner, in 1943. Kanner described 11 children who shared
the following symptomatology: extreme autistic aloneness, anxiously obsessive desire for the preservation
of sameness, excellent rote memory, delayed echolalia, oversensitivity to stimuli,
limitation in the variety of spontaneous activity, and good cognitive potentialities.
One year later, an Austrian
physician, Hans Asperger, independently described a group of children with a similar pattern
of symptoms. In a striking coincidence Asperger also chose the term 'autism' (the root is Greek
'autos' meaning self) thus emphasizing the social withdrawal evident in all cases. Kanner
and Asperger both noted the children's poor eye contact, stereotypies of word and movement,
and marked resistance to change.
In modern terminology, researchers and physicians refer to a triad of core problems:
- socialization
Autistic children show an inability or disinclination to share and direct attention.
They do not engage in pointing to things in order to share a focus of interest
('protodeclarative' pointing)
which is contrasted with pointing to things in order to attain them ('protoimperative'pointing).
They have difficulty with imitation, a potent source of social learning. Another way this
socialization deficit is manifested is through a lack of social referencing: responding
differently to a new situation according to the mother's facial expression. It is important to note
that while the socialization deficit is severe it is by no means global; autistic children can
form strong attachments to caregivers and are not all stereotypically aloof.
- communication
Language and nonverbal communication tend to be delayed and difficult to establish.
When language is developed, expressive gestures tend to be lacking; the speech of most
verbal autistic people is flat and monotonic, lacking in the usual prosody that carries
communicative intent. Pronoun reversals (saying "you' for "I") are common. Autistic speakers
tend to use words idiosyncratically and to create neologisms. There is generally a marked failure to
initiate or sustain conversation normally. Autistic children who speak usually show fairly
normal phonology and grammar. What is markedly impaired is pragmatic competence: the child's
use of language, which tends to be over-literal, as in the case of the boy who asked for glue
when he was told to "stick your coat anywhere".
- imagination
This is manifested in the conspicuous absence of spontaneous pretend or 'symbolic' play.
Instead of pretending objects are something else as normal preschoolers love to do,
autistic children prefer to engage in repetitive activities with the objects, such as lining
blocks up in a precise arrangement or continuously spinning toys. Autistic children show little
interest in narrative and fiction, displaying a strong preference for factual material, such
as bus and train timetables, sports statistics and so on.
All the epidemiological studies show a higher rate autism in boys than in girls, with reported
ratios ranging from 2:1 to 3:1. The sex ratio seems to vary with ability: most girls with autism
are at the lower end of the spectrum, while at the more able end boys may outnumber girls
by as much as 5:1. The genetic hypotheses about the root cause of this discrepancy are:
1) that females
are somehow affected more strongly by the autism gene or 2) there may be genetic heterogeneity
with more mild forms being X linked and hence more common in boys.
What Causes Autism?
Here a myth should be dispelled: autism is not caused by a cold and distant mother. Bruno
Bettelheim was responsible for the 'refrigerator mother' theory of autism, which was subsequently
adopted by Kanner. No evidence has emerged to support this theory and counterevidence is available
from the sad cases of abused and neglected children, such as Genie, who nevertheless fail
to develop autistic symptomatology.
Current evidence does point towards a biological basis for autism. Epilepsy, a brain
disorder, often accompanies autism. Another frequent concomitant of autism is mental retardation;
Sigman and Capps estimate that 75% of autistic children are also classified as mentally retarded.
A genetic basis is indicated by epidemiological studies: as stated above, autism is more common in boys,
and autism is 50 times more frequent in the siblings of autistic people than in the population at large.
Monozygotic (identical) twins have a far higher (but not perfect) concordance for autism than
dizygotic (fraternal) twins. Folstein & Rutter (1977) found that where MZ twins were discordant
for autism, the autistic twin was the one who had experienced a difficult delivery.
No agreement has yet emerged about the critical areas or pathways in the brain damaged in autism.
A number of different regions, including the cerebellum and the limbic system, are known to be
different in autistic brains. Autopsies reveal reductions in cell density in the cerebellum
and abnormalities in the hippocampus, and parts of the amygdala. A number of MRI scans provide evidence
of cerebellar abnormalities, particularly in the cerebellar vermis of relatively able individuals
with autism (sometimes referred to as 'Asperger's syndrome'). Many factors, including malnourishment,
viruses, toxic agents, drugs, and genetic mutations, can cause abnormal cerebellar development. Traditionally,
the cerebellum was thought to be the site of motor programming, but it has recently
been argued that the cerebellum contributes to normal cognitive functions
(Leiner, Leiner & Dow, 1986). It is not yet clear how abnormalities in the neocerebellar vermis
contribute to the
specific pattern of cognitive and behavioral deficits and skills found in autism.
Another brain area that has been implicated
in autism is the frontal lobes, on the basis of autistic people's difficulties with 'frontal
lobe' tasks such as the Wisconsin Card Sorting Test and The Tower of Hanoi.
What Are Savant Abilities?
The islets of abilities referred to by Kanner are splinter skills that are responsible for the
"idiot savant" characterization of some autistic people. About 1 in 10 autistic people show
isolated abilities much in advance of their overall intellectual abilities. These often occur
within the fields of music, calculation, and drawing. Phenomenal memory for detail within
the field of specialization often accompanies or comprises these savant abilities. For example,
the physician J. Langdon Down (for whom Down's Syndrome is named) reported giving one of his
patients 'The Decline and Fall of the
Roman Empire'; the patient memorized the entire weighty tome in one reading, and consistently
replicated and subsequently corrected a mistake of omitting one line on the third page.
Is Theory of Mind Absent in Autism?
In 1985 the British psychologists Uta Frith, Alan Leslie and Simon Baron-Cohen proposed that
the core deficit in autism is an inability to 'mind-read': the imputing of mental states to
the self and others, known in the developmental literature as 'theory of mind'. They explain
the triad of autistic deficits in terms of a lack of theory of mind: the inability to pretend stemming
from an inability to form the metarepresentations necessary for ToM; the socialization impairments
following from an inability to appreciate people as agents with independent minds; and the communicative
impairments arising from the an inability to recognize utterances as conveying the speaker's thoughts
and intentions. The appeal of such a theory is its ability to explain the diverse set of
inabilities and splinter skills characteristic of autism.
The 'theory of mind' theory of autism was experimentally tested with the now famous
'Sally-Ann' version of
Wimmer and Perner's false belief task. In this task the child is shown two dolls, Sally and Ann.
Sally has a basket and Ann has a box. The child watches as Sally places a marble in her basket and goes
out. While Sally is out Ann moves the marble into her box. Sally returns. The question posed to the child is,
'Where will Sally look for the marble.?'
Baron-Cohen, Leslie & Frith tested 20 autistic children
with mental ages well over 4 years; 16 (80%) failed to appreciate Sally's false belief.
In contrast, 12/14 children with Down's Syndrome of lower mental age succeeded on the task.
Baron-Cohen et al attributed the high rate of autistic children's failure on this false
belief task to an inability to 'mentalize', to consider the mental states of self and others.
Sources
- Happe, F. (1994) Autism: An Introduction to Psychological Theory, UCL Press: London.
- Sigman, M. & Capps, L. (1997) Children with Autism: A Developmental Perspective, Harvard
University Press: Cambridge, MA.