BRAIN LATERALIZATION AND ATTENTION ACROSS THE AUTISM SPECTRUM 1 Lateral Attention Processing Speed Differences in People with Autism Spectrum Disorders Ruifeng Li/Raymond Li S3842624 BESC1190 RMIT University Word count: 1441 BRAIN LATERALIZATION AND ATTENTION ACROSS THE AUTISM SPECTRUM 2 Autism spectrum disorders (ASD) were the subject of research for a long time with the aim to acquire knowledge about and understand both the disorders themselves and help the people suffering from them. When it was first defined, autism was seen as a specific disorder that affects a small number of children, but throughout the years it was shown that, instead of being a single disorder, autism represents a very wide range of different neurodevelopmental issues, which may differ in symptoms and severity. Recently, with the publication of DSM-V, all the previously existing categories (such as autistics disorder, Asperger’s syndrome, etc.) which may refer to autism were condensed into the diagnosis of ASD. The two common threads to the whole autism spectrum are issues with communication in social situations and repetitive, restricted sensory-motor behaviors. Multiple epidemiological studies have determined that the prevalence of ASD is around 1% (Lord et al., 2018). Due to these symptoms, people with ASD may experience hardship in many areas of their lives. These include interpersonal relationships, professional life, school, everyday interactions, etc. Throughout the years, many different therapeutical approaches were constructed in order to help people with ASD advance in their lives and live the best lives that they can, including early parent-mediated interventions; naturalistic behavioral developmental interventions; behavioral and social treatments for school- age children, adolescents, and adults; as well as pharmacological treatments. Even though the field has progressed immensely in the past, there is still a lot of work to be done in regards to understanding ASD enough to help people who struggle with it (Lord et al., 2018). Amongst other issues, which may be debilitating to the normal life and functioning of the persons suffering from ASD, attention deficits were determined to be another commonly faced issue. This is especially important in the context of the classroom and other situations in which it is important for children with ASD to pay attention to certain materials. If their attention is not BRAIN LATERALIZATION AND ATTENTION ACROSS THE AUTISM SPECTRUM 3 directed towards the material that they are being shown, there is no use for doing so. Therefore, many studies have dealt with the topic of attention, and especially spatial visual attention in people with ASD. In order to condense the previous research literature, Landry and Parker (2013) have conducted a meta-study, focusing on the usage of the Posner task for testing visual orientation in people with ASD. The Posner task, named after Michael Posner, who first created it (Posner, 1980), consists of a task that requires people to detect visual targets that may be given in different fields of their view. The visual targets can be preceded by cues, which may be shown on the same side that the target will be shown, contralaterally, or neutrally (for instance, in the center of the field of view). When the cue is given in the same side of the field of view as the target (which is referred to as a valid cue), the reaction is generally quicker than when it is not (an invalid cue), because visual attention is already directed towards the target, before it is presented. The difference in reaction time between valid and invalid cues is called the orienting effect. In this meta-study (Landry & Parker, 2013) it was demonstrated that, while people with ASD orient, their orienting is impaired in comparison to control groups. The average effect size of the differences between groups of people with ASD and control groups was d = 0.44, which can be considered a small effect size. Another way of assessing visual attention is through the phenomenon of spatial neglect. Some people, who have suffered unilateral neural lesions, experience the phenomenon of spatial neglect. This phenomenon means that they ignore the contralateral (from the lesion) field of vision. A similar effect (dubbed pseudoneglect) is present in healthy individuals as well, and it occurs when the attention is shifted slightly towards the left, because of the domination of the right parietal cortex in attention-related tasks (Bowers & Heilman, 1980). Since people with ASD have issues with attention and decreased activation of the right hemisphere (Landry & BRAIN LATERALIZATION AND ATTENTION ACROSS THE AUTISM SPECTRUM 4 Parker, 2013), it can be proposed that, for them, the effect of pseudoneglect will be lessened. This was demonstrated by English et al. (2015), who measured ASD through autism quotient (AQ, Baron-Cohen et al., 2001) and have shown a difference in the bias towards the left visual field for people with lower AQ scores, in comparison to people with higher AQ scores (who had lower leftward bias). Furthermore, they demonstrated a negative correlation between the leftward attentional bias and the social skills factor of ASD. This study will extend previous findings by taking into account not only the spatial direction of attention, but also the speed of processing. More specifically, it will be tested whether or not information from different visual fields is processed with different speeds, in relation to the level of AQ of a person. If this is the case, and people with ASD processed certain information slower, that would help in explaining the difficulties they face in social situations. This can be expected, due to the finding of English et al. (2015) that the leftward attentional bias has a negative correlation with social skills. Therefore, based on the provided rationale, it is the aim of this study to investigate whether or not there is a difference in the speed of processing of visual stimuli, depending on the field of vision, for people with different levels of AQ. Methods Participants The sample consisted of 371 (268 female, 95 male, 4 non-binary) participants. The mean age was 23.7 (SD = 3.97). 327 participants were right-handed, 31 were left-handed, while 10 were ambidextrous. The average AQ of the sample was 60.44 (SD = 9.9). Materials BRAIN LATERALIZATION AND ATTENTION ACROSS THE AUTISM SPECTRUM 5 In order to determine the levels of ASD symptoms in the sample, the Autism Spectrum Quotient – AQ-short was used (Hoekstra et al., 2011). The scale has 2 higher-order factors: social behavior and fascination with numbers and patterns. It consists of 28 items which are answered through a 4-point Likert-type scale (1 – “definitely agree”, 2 – “slightly agree”; 3 – “slightly disagree”; and ‘‘4 - “definitely disagree”). The internal reliability of the scale has been shown as stable and relatively high (Chronbach’s α values ranging from .77 to .86). The scale has been shown as valid in both the general population and in different clinical populations (Hoekstra et al. 2011). In order to measure the speed of processing of the participants, two reaction time tasks were conducted. The tasks were adapted from Deary et al. (2011) and can be accessed through www.psytoolkit.org/. The first task was a simple reaction time task, in which the participants were presented with a blue background that has a white square in the middle. At random time intervals, a black x appeared in the middle of the white square, and it would stay there until the participant responded. The participants were instructed to press the space bar as soon as they saw the x, using their dominant hand. There were 8 practice trials (for which the reaction times were not recorded) and 20 test trials. This task was used to obtain the baseline of the participants’ time of reaction. The second task was a choice reaction task, that had a similar setup to the previous one. However, instead of one, there were four white squares organized in a horizontal line in the middle of the screen. Two of the squares were placed left from the middle of the screen and two were positioned to the right. At random time intervals and in a random order, a black x appeared in one of the four boxes. The participants were instructed to respond by pressing the button that was designated as the response button for the box in which the x would appear. There were four buttons BRAIN LATERALIZATION AND ATTENTION ACROSS THE AUTISM SPECTRUM 6 used: the button “z” for the leftmost box, the button “x” for the one right to it, the button “,” for the third one, and the button “.” for the rightmost one. Once the participant responded, the x would disappear. There were 8 practice trials and 40 test trials. This task was used to determine the “left” reaction time and the “right” reaction time of the participants. Procedure The participants completed the procedure online using their personal computers, at home. They were instructed to sit at an arm’s length from the screen and rid themselves of all potential distractions, completing the whole procedure in one go. They first completed the AQ-short survey. Then, they used the website www.psytoolkit.org to access the reaction time tasks. They first completed the simple reaction time task and then the choice reaction time task. BRAIN LATERALIZATION AND ATTENTION ACROSS THE AUTISM SPECTRUM 7 References: Bowers, D., & Heilman, K. M. (1980). Pseudoneglect: Effects of hemispace on a tactile line bisection task. Neuropsychologia, 18(4–5), 491–498. https://doi.org/10.1016/0028- 3932(80)90151-7 Deary, I. J., Liewald, D., & Nissan, J. (2011). A free, easy-to-use, computer-based simple and four-choice reaction time programme: The Deary-Liewald reaction time task. Behavior Research Methods, 43(1), 258–268. https://doi.org/10.3758/s13428-010-0024-1 English, M. C. W., Maybery, M. T., & Visser, T. A. W. (2015). Individuals with Autistic-Like Traits Show Reduced Lateralization on a Greyscales Task. Journal of Autism and Developmental Disorders, 45(10), 3390–3395. https://doi.org/10.1007/s10803-015-2493- 7 Hoekstra, R. A., Vinkhuyzen, A. A. E., Wheelwright, S., Bartels, M., Boomsma, D. I., Baron- Cohen, S., Posthuma, D., & van der Sluis, S. (2011). The Construction and Validation of an Abridged Version of the Autism-Spectrum Quotient (AQ-Short). Journal of Autism and Developmental Disorders, 41(5), 589–596. https://doi.org/10.1007/s10803-010-1073-0 Landry, O., & Parker, A. (2013). A meta-analysis of visual orienting in autism. Frontiers in Human Neuroscience, 7. https://doi.org/10.3389/fnhum.2013.00833 Lord, C., Elsabbagh, M., Baird, G., & Veenstra-Vanderweele, J. (2018). Autism spectrum disorder. The Lancet, 392(10146), 508–520. https://doi.org/10.1016/S0140-6736(18)31129-2 Posner, M. I. (1980). Orienting of Attention. Quarterly Journal of Experimental Psychology, 32(1), 3–25. https://doi.org/10.1080/00335558008248231




























































































































































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