Download powerpoint

Perception and Dyslexia
Mr Patrick Mulcahy, Chair ASASA

Perception is the
process of acquiring,
interpreting, selecting,
and organising sensory
information

Brain is the organ of
perception

Neurological processing
underlies our perception
Perception

Darwinian natural selection over countless
generations has shaped our sense organs.

They have been shaped to give us a useful picture of
the world, to help us to survive.

What sense organs do is to construct a useful model
of the world…a kind of virtual reality simulation of the
real world.

Very difficult to free oneself from the shackles of preconception and ‘common sense’.
Perception

If reality was
represented as the
keys on a piano,
human perception
would be limited to a
single chord
Developmental Dyslexia

Professor John Stein, Magdalen College,
Oxford, states that ‘dyslexia has an
organic neurological basis and, contrary
to previous strongly held beliefs, it is not
'purely psychological’

Professor Stein sees a definite correlation
with abnormal magnocellular neurones
Magnocellular Region
Correlation with Dyslexia:
Sound and vision being
processed differently in
this one area of the brain
with tasks involving
literacy
There are two partially independent
mechanisms for reading:
phonological and visual.
Reading and Perception

Saying the colours
rather than reading
the words
demonstrates the
separate processes
The Phonological Model

The phonological model of dyslexia defines it in terms of
difficulties associated with converting phonemes (‘smallest
meaningful segment of language’) into symbols (letters).

The mental activity associated with reading can be divided into
word identification, phonological processing, and cognitive
reasoning.

A deficit in phonological processing will reduce a person’s ability
to convert symbols into sounds (reading) and/or sounds into
symbols (writing) thus preventing them from exhibiting their true
cognitive ability.
READING

Different combinations of 44 phonemes produce every word in
the English language as with the example used above i.e.

CAT = ‘Kuh’, ‘aah’ and ‘tuh’.

Before words can be identified, understood, stored in memory or
retrieved from it they must first be broken down or parsed, into
their phonetic units by the phonological module of the brain.

There is no overt clue to the underlying segmental nature of
speech and speech appears seamless, i.e. an oscilloscope
would register the word ‘cat’ as a single burst of sound
READING AND DYSLEXIA

Reading is not natural as it is a human invention
which must be learned at a conscious level. A child
has to learn that orthography (the sequence of letters
on the page) represents the phonology. This is what
occurs when a child learns to read.

When a child has dyslexia, a deficit within the
language system of the phonological module impairs
his/her ability to segment the written word into its
underlying phonological components. The deficit in
phonological can prevent word identification.
READING AND DYSLEXIA





Difficulties with rote memorisation;
Difficulties with rapid word retrieval;
Difficulties with reading – decoding words automatically can be
difficult and the additional energy consumed on this tends to
lessen comprehension i.e. students with dyslexia rely more on
context when reading and this slows them down;
Spelling difficulties can be similarly accounted for as the same
process is used when converting sounds into symbols (writing);
The additional work required by the brain to decode symbols
can result in tiredness and concentration can consequently
suffer
VISION AND DYSLEXIA
VISION AND DYSLEXIA
Reading requires a series of
eye fixations and saccades
to the next word.
How could a visual magnocellular deficit
cause reading problems?
 The
magnocellular deficit in dyslexics is
mild.
 Hence letters appear to move around
and their order becomes confused
Magnocellular processing sharpens:
into:
SYMPTOMS OF VISUAL
DYSLEXIA
THE NEUROLOGICAL
EFFECTS OF DYSLEXIA

Difference in the
area of the brain
affecting visual and
phonological
processing
 The net result of
this is that their
perception of
literacy will be
different.
Non-Dyslexic Student
Student with Dyslexia
Brain Mapping reveals that people with dyslexia
rely on different parts of the brain when reading
and writing.
The Needs of Students with
Dyslexia
 Context

is Higher Education
Research, Composition, Proofreading,
Note-taking and Time Management
 Teaching
is Lecture-based
The Needs of Students with
Dyslexia
 Students
with Auditory
Sequential Working Memory and
Visual Memory Deficits need
Different teaching and Learning
strategies