Speaker identification is a challenge for cochlear implant users because their prosthesis restricts access to the cues that underlie natural voice quality. The present thesis examined speaker recognition in the context of spectrally degraded sentences. The listeners of interest were child implant users who were prelingually deaf as well as hearing children and adults who listened to speech via vocoder simulations of implant processing. Study 1 focused on child implant users' identification of a highly salient speaker—the mother (identified as mother)—and unfamiliar speakers varying in age and gender (identified as man, woman, or girl). In a further experiment, children were required to differentiate their mother's voice from the voices of unfamiliar women. Young hearing children were tested on the same tasks and stimuli. Although child implant users performed more poorly than hearing children overall, they successfully differentiated their mother's voice from other voices. In fact, their performance surpassed expectations based on previous studies of child and adult implant users. Even when natural variations in speaking style were reduced, child implant users successfully identified the speakers. The findings imply that person-specific differences in articulatory style contributed to implanted children's successful performance. Study 2 used vocoder simulations of cochlear implant processing to vary the spectral content of sentences produced by the man, woman, and girl from Study 1. The ability of children (5-7 years and 10-12 years) and adults with normal hearing to identify the speakers was affected by the level of spectral degradation and by the gender of the speaker. Female voices were more difficult to identify than was the man's voice, especially for the younger children. In some respects, hearing individuals' identification of degraded voices was poorer than that of child implant users in Study 1. In a further experiment, hearing children and adults were required to provide verbatim repetitions of spectrally degraded sentences. Their performance on this task greatly exceeded their performance on speaker identification at comparable levels of spectral degradation. The present findings underline the importance of ecologically valid materials and methods when assessing speaker identification, especially in children. Moreover, they raise questions about the efficacy of vocoder models for the study of speaker identification in cochlear implant users.

The ability to control one’s behaviour is a fundamental cognitive function subserved by the prefrontal cortex (PFC). Whereas the neural basis of inhibitory control is reasonably well-established, the possible influence of individual differences in personality on cortical activity associated with this ability remains largely unexplored. The present study obtained self-report ratings of Five-Factor Model personality traits from 42 healthy adults while hemodynamic oxygenation in the PFC was recorded during a Go/No-Go task. Results indicated that Neuroticism, Agreeableness and Openness to Experience were associated with attenuated activity in the lateral PFC, a region critical for emotion regulation and behavioural control, whereas Extraversion and Conscientiousness were associated with greater activation in these regions. Activity within the medial PFC, an area linked to task engagement and self-monitoring, shared a positive association with Agreeableness. These findings provide important insights into how neural systems supporting inhibitory control may be affected by individual differences in personality.

The purpose of this study was to compare the effects on speech acoustics of a wide variety of speaking instructions that have been used across different studies on clear speech, and to investigate the acoustic and articulatory changes that occur in response to these instructions and in different talking environments. Five young adult females were recorded speaking under different instructions meant to elicit more intelligible speech, and measures of speaking rate, speaking F0 and intensity were found to distinguish instructions to speak "as if to someone with hearing loss" from instructions to speak "clearly" or "slowly", which produced different results from instructions to speak "loudly" or as if in noise. Preliminary acoustic and articulatory data are described for a sixth talker who spoke under a subset of these instructions, and in both a quiet and a noisy talking environment.

The purpose of this study was to compare the effects on speech acoustics of a wide variety of speaking instructions that have been used across different studies on clear speech, and to investigate the acoustic and articulatory changes that occur in response to these instructions and in different talking environments. Five young adult females were recorded speaking under different instructions meant to elicit more intelligible speech, and measures of speaking rate, speaking F0 and intensity were found to distinguish instructions to speak "as if to someone with hearing loss" from instructions to speak "clearly" or "slowly", which produced different results from instructions to speak "loudly" or as if in noise. Preliminary acoustic and articulatory data are described for a sixth talker who spoke under a subset of these instructions, and in both a quiet and a noisy talking environment.

The ability to control one’s behaviour is a fundamental cognitive function subserved by the prefrontal cortex (PFC). Whereas the neural basis of inhibitory control is reasonably well-established, the possible influence of individual differences in personality on cortical activity associated with this ability remains largely unexplored. The present study obtained self-report ratings of Five-Factor Model personality traits from 42 healthy adults while hemodynamic oxygenation in the PFC was recorded during a Go/No-Go task. Results indicated that Neuroticism, Agreeableness and Openness to Experience were associated with attenuated activity in the lateral PFC, a region critical for emotion regulation and behavioural control, whereas Extraversion and Conscientiousness were associated with greater activation in these regions. Activity within the medial PFC, an area linked to task engagement and self-monitoring, shared a positive association with Agreeableness. These findings provide important insights into how neural systems supporting inhibitory control may be affected by individual differences in personality.

Children with traumatic brain injury (TBI) often experience difficulties with inhibitory control (IC), manifest in both neurocognitive function (poor performance on the stop signal task, SST) and behavior (emergence of de novo attention-deficit/hyperactivity disorder, or secondary ADHD, S-ADHD). IC allows for the regulation of thought and action, and interacts with reward to modify behaviour adaptively as environments change. Children with developmental or primary ADHD (P-ADHD) exhibit poor IC and abnormalities when responding to rewards, yet the extent to which S-ADHD is similar to and different from P-ADHD in terms of these behaviours is not well-characterized. The cancellation and restraint versions of the SST were used to examine the effects of rewards on 2 distinct forms of IC in children and adolescents divided into 4 groups (control, TBI, S-ADHD, and P-ADHD). The SST requires participants to respond to a “go signal” and inhibit their responses when encountering a “stop signal”. Rewards improved performance similarly across groups, ages, and cancellation and restraint IC tasks. Adolescents exhibited better IC and faster and less variable response execution relative to children. Significant IC deficits were found in both tasks in the P-ADHD group, with participants with S-ADHD exhibiting intermediate cancellation performance relative to the other groups. Participants with TBI without S-ADHD were not impaired on either task. The relationship between neurocognitive and behavioral IC was examined by comparing multi-informant ratings of IC across groups, and examining the relationship between ratings and IC performance on the SST. Participants in the control and TBI groups were rated within the typical range, and exhibited fewer problems than either of the ADHD groups, who differed from each other (the P-ADHD group was rated as more inattentive than the S-ADHD group). Moderate to high concordance was found between parent and teacher reports, each of which was poorly concordant with self-reports. The P-ADHD and S-ADHD groups were unaware of their own deficits. Poorer IC predicted parent and teacher classification of participants into ADHD subtypes, although IC did not predict rating concordance. Despite similar clinical presentations, S-ADHD and P-ADHD differ in the phenotypic expression of behaviour and manifestation of IC across contexts.

This thesis investigates the effect of a feedback-reward system on speeding and tailgating behaviours. Data utilized in this study were collected from 37 participants through a field trial commissioned by Transport Canada. In this trial, a feedback-reward system was investigated, which provided feedback and rewards to the drivers based on speed limit compliance and safe headway maintenance. The trial consisted of three phases: baseline, intervention, and post-intervention. During the intervention phase, real-time feedback was provided on an in-vehicle display. Participants also accumulated reward points and could view related information on a website. Results indicate that the intervention resulted in a significant increase in speed limit compliance, and this positive effect, although dampened, was still apparent after system removal. Similarly, results on headway compliance rate indicate a positive intervention effect, however, this effect did not sustain after system removal. These findings have implications for developing better aids to improve driving behaviour.

Mindfulness training cultivates momentary awareness, a form of attention directed to non-evaluative, immediate sensation. This form of attention stands in contrast to a more temporally extended awareness, which allows for the evaluative organization of experience into a personal narrative. The neural mechanisms underlying such awareness, and their role in regulating emotions, are poorly understood. Thus, in three functional magnetic resonance imaging (fMRI) experiments, I explored the thesis that momentary and extended awareness represent dissociable modes of self-reference, with momentary self-reference reducing ruminative elaboration of events by biasing attention towards interoceptive signals from the body. I compared individuals who were randomly-assigned to either an 8-week Mindfulness-Based Stress Reduction (MBSR) training course against a waitlisted group (Controls). Three distinct studies examined the impact of Mindfulness on: 1) the contrast between explicitly directed momentary and extended self referential processing; 2) reactions to an induced sadness challenge; and 3) the contrast between interoceptive (breath-monitoring) and exteroceptive (visual) attention. In all three studies MBSR led to a shift in neural activity away from cortical midline structures, such as the medial prefrontal and posterior cingulate cortices, to predominantly right-lateralized viscerosomatic structures, and specifically the insular cortex. Cortical midline activity is thought to support habitual patterns of evaluation, and stands as the neural correlate of a narrated, extended self, while right-lateralized insula activity is thought to represent the recurrent integration of present moment context, the neural correlate of the momentary self. These data revealed that MBSR may enhance the distinction between momentary and extended self-reference, reducing cortical midline responses and recruiting a novel, right-lateralized viscerosomatic network. Additionally, MBSR graduates demonstrated reduced emotional reactivity to a film-based sadness mood induction, reducing cortical midline activity and inhibition of the right insula. Moreover, the MBSR group demonstrated enhanced right middle insula recruitment during the monitoring of sensory experience associated with breath monitoring, a core mindfulness practice. The data from this final study also suggest that MBSR promoted an integration of posterior insular sensory representations with anterior insular subjective representations of present moment status. Preserved viscerosomatic activity in the face of emotional challenge may be a predictor of enhanced well-being following mindfulness training.

This thesis investigates the effect of a feedback-reward system on speeding and tailgating behaviours. Data utilized in this study were collected from 37 participants through a field trial commissioned by Transport Canada. In this trial, a feedback-reward system was investigated, which provided feedback and rewards to the drivers based on speed limit compliance and safe headway maintenance. The trial consisted of three phases: baseline, intervention, and post-intervention. During the intervention phase, real-time feedback was provided on an in-vehicle display. Participants also accumulated reward points and could view related information on a website. Results indicate that the intervention resulted in a significant increase in speed limit compliance, and this positive effect, although dampened, was still apparent after system removal. Similarly, results on headway compliance rate indicate a positive intervention effect, however, this effect did not sustain after system removal. These findings have implications for developing better aids to improve driving behaviour.

Users of cochlear implants typically have difficulty differentiating talkers, identifying vocal expressions of emotion, and recognizing familiar melodies because of the degraded spectral cues provided by conventional implants. This thesis examined these abilities in a small, relatively privileged sample of young bilateral implant users. In Study 1 child implant users and a control sample of hearing children were required to judge whether various utterances were produced by a man, woman, or girl (Experiment 1) and to identify the voices of cartoon characters from familiar television programs (Experiment 2). Child implant users’ performance on talker classification was comparable to that of hearing children. Their identification of cartoon characters’ voices was less accurate than that of hearing children but well above chance levels. These findings challenge conventional wisdom about the talker identification difficulties of implant users. In Study 2 the children were required to indicate whether semantically neutral utterances (Experiment 1) or classical piano excerpts (Experiment 2) sounded “happy” or “sad”. In both cases, implant users performed less accurately than hearing children but well above chance levels. Although the findings on emotion recognition in music are in line with those of previous research, the findings on emotion in speech are at odds with claims that young implant users are insensitive to vocal affect. In Study 3 the children were required to identify the theme songs from familiar television programs on the basis of combined timing and pitch cues as well as timing or pitch cues alone. Implant users’ performance was comparable to that of hearing children except when the cues were restricted to pitch relations, which resulted in performance at chance levels. The findings suggest that the musical representations of young implanted listeners include precise information about timing and coarser information about pitch. They also demonstrate, for the first time, that children, both implant users and those with normal hearing, can identify familiar music on the basis of timing cues alone. Overall, the findings highlight the importance of timing cues for implant users, the range of individual differences, and habilitation possibilities for the recognition of talkers, emotion, and music.