Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Psychology

Program Name/Specialization

Cognitive Neuroscience

Faculty/School

Faculty of Science

First Advisor

Nichole Scheerer

Advisor Role

Primary supervisor

Abstract

Fluent speech production is achieved through a relative weighting of feedback and feedforward motor control systems. These systems are thought to be responsible for the online correction of vocal errors and initiating speech, respectively. The relative weighting of these motor control systems has been shown to differ under conditions of high attentional load and across individual differences in sensory acuity. However, research has yet to examine speech motor control in a population with clinical attentional and sensory processing differences, such as those with Attention-Deficit Hyperactivity Disorder (ADHD). The studies in this thesis aimed to examine how ADHD traits relate to speech motor control in children and adults with and without ADHD and review our current understanding of auditory cortical processing in ADHD. To do this, Study 1 focused on auditory cortical processing by systematically reviewing the current state of literature surrounding auditory evoked potentials (AEPs) in individuals with and without ADHD. Study 2 and 3 examined the relationships between ADHD traits and speech motor control in children and adults with and without ADHD. To examine speech motor control, frequency- altered feedback (FAF) tasks were used to manipulate participants’ auditory feedback and vocal compensations to sudden 100 cent pitch perturbations were measured as an index of feedback control. To measure ADHD traits, particularly attention and sensory processing abilities, the sustained attention to response task (SART), the Short Sensory Profile (SSP), and the Adult/Adolescent Sensory Profile (AASP) were used. Study 1 revealed that across the literature, children and adults with ADHD tend to show decreased amplitudes and prolonged latencies of the N200 and P300 auditory components compared to controls. This was most reported towards pitch deviated pure tones, while speech stimuli elicited greater group differences in the P300 component. Study 2 revealed that sensory processing patterns, but not attention, were related to an increased weighting of feedback control during speech production in children without ADHD. Similarly, the findings of Study 3 also revealed the importance of sensory processing differences, rather than attention, in adults with and without ADHD. However, unlike in children, increased sensory differences were linked to a decreased weighting of feedback control. Further, while speech motor control seems to be largely unaffected in adults with ADHD, some neural differences were reported in the P200 and N200 components suggesting that perhaps auditory cortical processing of FAF may differ within ADHD, but that more complex speech tasks may be required to see behavioural differences. Overall, the results of this thesis suggest that while auditory cortical processing differs in response to speech and non-speech stimuli in ADHD, their speech motor abilities remain largely intact. Instead, it is individual differences in sensory processing patterns rather than attention that influences the weighting of feedback and feedforward control in children and adults, regardless of ADHD diagnosis.

Convocation Year

2026

Convocation Season

Fall

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