The Canadian Dyslexia Centre’s History
Before the National Institutes of Health in the U.S.A. began to research dyslexia in the 1980s, dyslexia could only be diagnosed by exclusion.
That is, if a child’s reading difficulties could not be explained by limited intelligence, auditory or vision problems, the lack of access to education or another problem, it would be deduced that the child was dyslexic.
This did not satisfy parents, teachers or researchers, and efforts were made to fill the knowledge gap about dyslexia.