Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Psychology

Supervisor

Stevenson, Ryan A.

Abstract

In daily life, we are constantly bombarded with sensory information from multiple sources. Our ability to combine these cues into a single perceptual experience is known as multisensory integration. This process can be disrupted in neurodevelopmental conditions, such as autism spectrum disorder and dyslexia, affecting cognitive functions and language. Multisensory integration may be affected in attention-deficit/hyperactivity disorder (ADHD), though findings are conflicting. To explore these discrepancies, we conducted a meta-analysis to appraise the current state of the literature, elucidate observed inconsistent findings, and identify gaps in ADHD research. Then, we conducted studies to investigate multisensory integration in youth and adults with and without ADHD using behavioural tests and electroencephalography (EEG).

In the first study, youth (ages 6-17) with ADHD (n=53) and without ADHD (n=60) completed tasks such as the Sound-Induced Flash Illusion (SIFI), McGurk task, and a speech-in-noise task. No group differences were found in the SIFI, but ADHD youth showed reduced susceptibility to the McGurk illusion compared to neurotypical (NT) youth. The speech-in-noise task revealed no differences in multisensory gain, though hyperactive-impulsive traits were negatively related to phoneme accuracy.

In the second study, youth (ages 8-17) with ADHD (n=30) and without ADHD (n=23) performed a speeded-response time task while EEG recorded their responses to auditory, visual, or combined stimuli. No differences in multisensory gain were found, but ADHD youth showed delayed integration in occipital regions.

In the third study, adults (ages 18-59) with ADHD (n=32) and without ADHD (n=32) completed perception-matched and stimulus-matched detection tasks. ADHD adults showed higher response-time gain in the perception-matched task but no differences in the stimulus-matched task. EEG revealed differences in multisensory integration in frontal and occipital regions, more pronounced in the perception-matched task, possibly due to task difficulty or controlled unisensory perception.

Overall, our findings suggest that ADHD affects multisensory integration, influenced by task demands and age. This is important because multisensory integration supports the development of higher-order cognitive functions and language, and challenges with multisensory integration may impact these processes. Future research in ADHD should investigate multisensory integration across development, the relationship between attention and integration, and multisensory integration and cognitive functioning.

Summary for Lay Audience

In everyday life, we are presented with a vast amount of sensory information from different sources like sights and sounds. Our ability to combine cues from multiple senses into a single perceptual experience is called multisensory integration. Multisensory integration can be affected in different neurodevelopmental conditions, such as autism spectrum disorder and dyslexia. When multisensory integration is affected, it can have downstream effects on higher-order cognitive functions and language functioning. Increasing evidence shows that multisensory integration might be affected in people with attention-deficit/hyperactivity disorder (ADHD), but results have been conflicting. This led us to first analyze the current research to understand the conflicting results and identify gaps in literature. Then, we conducted studies to investigate multisensory integration in youth and adults with and without ADHD using behavioural tests and electroencephalography (EEG).

Our most consistent finding was a reduced neural response to multisensory integration in ADHD, especially in adults compared to youth and while using a task controlling for unisensory differences in sensory perception. This meant that their brains responded less to combining sensory information from different sources. In line with previous studies on adults with ADHD, our behavioral results showed a larger multisensory gain for response times when using basic stimuli (e.g., patches of lines and beeps) but reduced integration when dealing with more complex stimuli, such as speech. Adults with ADHD showed differences in multisensory integration for the response time measure compared to adults without ADHD, whereas youth with ADHD did not differ from youth without ADHD. This suggests people with ADHD might respond faster when combining basic sensory inputs, but their brains have a harder time integrating more complex information.

Overall, our findings suggest that people with ADHD show differences in how they integrate sensory information. This is important because multisensory integration is a building block for the development of higher-order cognitive functions and language and challenges with multisensory integration may impact the development of these processes. Future research should investigate how these differences develop over time in people with ADHD, how attention affects multisensory integration, and the impact of altered multisensory integration on cognitive functions in ADHD.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

Download

Share

COinS