In this paper the researchers have developed and discussed the question regarding the memory capacity of dyslexic individuals compared to those who don’t have dyslexia. The hypothesis that dyslexic individuals have a lower working memory capacity was checked in this study. To check this hypothesis the researchers have used basics of statistical methods and probability theory. The analysis was performed on a data sample comparing the working memory capacity in dyslexic and non-dyslexic individuals by using the symmetry span (working memory measure).
The researchers have used descriptive statistics and Student’s independent samples t-test to check the hypothesis. All calculations were performed in SPSS 22 statistical software. It is appeared that the value of the symmetry span for those who has dyslexia was on average only 5.7 compared for 13.9 to those who haven’t it. This difference was checked by using Student’s t-test and the results of the test showed that the null hypothesis should be rejected. There is enough evidence to say that there is a significant difference in memory capacity between dyslexic and non dyslexic individuals. However, there was performed a two-tailed test which is used only to check the difference, but it doesn’t tell us about which of two mean values are significantly bigger and which one is lower. But based on the descriptive statistics it is enough evidence to conclude, that the working memory capacity is lower for dyslexic individuals.
This study confirms a number of studies conducted earlier. Numerous studies have shown that dyslexic adults have symptoms of varying severity, which depend on the cause of the violation. A person suffering from dyslexia cannot quickly and correctly recognize words, read it often makes spelling mistakes. An individual is not formed a complete phonological component of language. A person with dyslexia may suffer memory and attention, but as a rule, it is connected with the violation of interhemispheric interactions. In this disorder may be a shortage of the reader's experience. A person with dyslexia usually has a bad understanding of the text. Intelligence thus violating saved. The individual reads with errors on the first syllable trying to guess what is written. People often do not understand what is written in the text, it is difficult to summarize the reading. Reading has been difficult, he quickly tired and irritated. These people make a number of grammatical or spelling errors in copying plain text, they find it difficult to correctly write the word perceived by ear. The individual with this neurological disorder has a lot of problems with handwriting, cannot perform the writing task in a short time. Dyslexia and dysgraphia lay "imprint" on the character of a person has high emotional, very irritable, impulsive makes mistakes. Very often the disease is accompanied by emotional instability. In character traits can manifest a strong sense of justice or refined aesthetic taste. The dominant feature of the right hemisphere may manifest as poor coordination of movements.
The results of this study show first of all that the one of the factors which may cause the symptoms of dyslexia is a real problem with a working memory capacity. Most researchers studying the problem of dyslexia in children, says a history of pathological effects of biological factors that cause minimal brain dysfunction. That’s why the understanding the initial causes of the problem helps to understand better ways of treatment. Dyslexia prevention should begin in the preschool years, developing in children visuospatial functions, memory, attention, analytic-synthetic activity, fine motor skills. It plays an important role to overcome violations pronunciation of sounds, the formation of lexical and grammatical structure of speech. The need for timely identification of children with speech disorders, speech therapy and conducting classes, preparing for the development of reading and writing.
However, there are some limitations of the study. The first limitation is related to that the experiment and comparison was performed only once. To be sure that the results of the study are accurate it is better to compare a number of different data samples to see that the tendency in a significant difference between memory capacity of dyslexic and non-dyslexic individuals stays from sample to sample. The second limitation is due to the fact that the problems with memory capacity may be caused by other diseases, such as Attention Deficit, Hyperactivity Disorder (ADHD), etc. To avoid this limitation it should assumed or checked that the participants of the study are not affected by such diseases. The third limitation is related to the assumptions of the statistical test: it should be assumed that there are no other significant factors which may affect the working memory capacity was omitted in this study. The people chosen for the research should not have any other causes on their memory capacity – only dyslexia (or its absence, for non-dyslexic individuals). If there are exist some “third” factors which had a significant effect on the values of working memory capacity, it may bias the result of this study.
Finally, there are several assumptions related to the method of mean values comparison. It is known that there must be no significant outliers in the data and the dependent variable (working memory capacity) should be approximately normally distributed. These assumptions may be checked by performing some non-parametric tests for distributions, for example, Kolmogorov-Smirnov test of Shapiro-Wilk test. The last assumption is related to homogeneity of variances. However, it was checked in the analysis section by using Levene’s test.
The study can be improved if all assumptions will be checked and met. The main issue to avoid is the influence of other significant factors. For this purpose it is better to make testing separately by gender, approximately for the same age group and so on. The influence of third factors must be reduced to a minimum.