WHY ASSESSING BRAIN LATERALITY IN DYSLEXIA?

Atypical structural and functional brain asymmetry is one of the most popular etiological theories of dyslexia and yet it is not definitively proven or disproven, despite the ongoing research in the area. The two main questions remain open:

- Is there a clear relationship between dyslexia and atypical brain lateralization?

- Is the atypical brain lateralization, if present, a cause or a consequence of dyslexia?

Since Samuel Orton’s times – meaning for almost 100 years now (Orton, S., 1925), scientists have been looking for the answers of these questions and we still do not have conclusive results even for the first one. Indeed, the hypothesis has gathered empirical evidence throughout the years, but the data in the scientific literature is inconsistent and sometimes even conflicting. That may be due to the assessment tools chosen, to the small sample sizes, to the heterogeneity of dyslexia or a combination of these factors.

Considering all the above, an online battery of validated behavioural tests might have a huge contribution, as it enables easily testing a big sample of dyslexics all over the world, thus providing statistically significant results. Proving or disproving the link between dyslexia and atypical brain lateralization, will give us green light to really focus on a third question, which I, as a practitioner and not only a researcher, consider actually the most important:

- How can we use the awareness of an atypical lateralization, when present, to provide more effective interventions?

WHY JOINING IN THE CURRENT STUDY?

- It is a contribution to finding a definitive answer to one of the biggest questions about dyslexia.

- It is fun.

- It is anonymous.

- Although the public results are anonymous, it is possible for the interested families to know their child’s individual results, either just to have a better awareness on how their child is functioning or to use that knowledge for tailored intervention and education.

DETAILS ABOUT THE CURRENT STUDY

Please read carefully the information below before completing and submitting the Informed Consent and Registration Form.

IN BRIEF

The current study aims at assessing the hemispheric lateralization for a number of verbal and non-verbal functions in school-aged children with dyslexia and at comparing it to the one of typically developing peers. It uses an online battery of validated behavioural tests, kindly shared by a scientific team from the Department of Experimental Psychology at Oxford University (Parker, A. J., Woodhead, Z. V., Thompson, P. A., & Bishop, D. V., 2021). It takes between 15 and 60 minutes to complete, depending on how fast the participant goes through the instructions and the rehearsal trials before each task and also on how many breaks they take between the tasks.

DESIGN

The study is built and administrated by Gorilla Experiment Builder (www.gorilla.sc) – an internet platform for creating experiments and collecting data for the purposes of the cognitive-behavioural sciences (Anwyl-Irvine, Massonnié, Flitton, Kirkham, & Evershed, 2020).

1. Methods and Instruments

1.1. Basic demographics questionnaire

1.2. Porta Test for dominant eye (Porac, C., & Coren, S., 1976)

1.3. Edinburgh Handedness Inventory (Oldfield, 1971)

1.4. Dichotic listening task for assessing language lateralization – a validated dichotic paradigm (Westerhausen R & Samuelsen F, 2020).

1.5. Chimeric faces task – a validated test for assessing lateralization during face and emotions processing (Yovel, G., Tambini, A., & Brandman, T., 2008).

1.6. Finger tapping task – a novel online alternative to the traditional Annett's Peg Moving Task for assessing motor laterality (Parker, A. J., Woodhead, Z. V., Thompson, P. A., & Bishop, D. V., 2021).

2. Recruitment Requirements For The Experimental Group

2.1. School age (8-17 y.o.)

2.2. Official diagnosis of Specific Learning Disorder/Dyslexia

2.3. No temporary or permanent sensory impairments or difficulties which may interfere either with the performance during the auditory, visual and motor tasks or with the laterality indexes resulting from them. The study is looking for a possible bigger proportion atypical laterality related to dyslexia and not to other causes.

3. Recruitment Requirements For The Control Group

3.1. School age (8-17 y.o.)

3.2. Good language skills and no serious problems with math

3.3. No temporary or permanent sensory impairments or difficulties which may interfere either with the performance during the auditory, visual and motor tasks or with the laterality indexes resulting from them.

4. Anonymity

Every participant will be given an ID and their name will not be displayed publically anywhere.

5. Technical Requirements

            5.1. Internet connection

            5.2. A laptop or a desktop computer. Participants cannot go through the tasks on their mobile phones or tablets.

5.3. Stereo headphones – needed for the auditory verbal task

5.4. Any type of plastic card with the size of a standard bank card - needed for calibrating the screen before the visual task.

6. General procedure

After each participant’s personal and parental informed consent and agreement to join in the study, they or their parents will receive a link to the experiment via email, provided they are eligible for the experimental or the control group. Depending on what is suitable for everyone involved, the experimenter may be virtually present during the experiment thanks to a video platform (Zoom, Skype, FaceTime, Viber or WhatsApp) or may have a previous communication on organizational details and instructions with the parent, the teacher or any other adult, who will assist the child in person. The goal of any of those options is to ensure that the child will go through each task and questionnaire the correct way. In case the experimenter is not present, the adult accompanying the child should read him or her the instructions, before each task or questionnaire and start it only after making sure everything is clear and the child is ready. For double reassurance, each task of the real experiment is preceded by practice trials. The children may choose to click the answers themselves or, alternatively – to respond orally for the present adult to click the chosen answer. The present adult should not suggest the answer in any way.