In the study of language production in aging, an important question relates to the relationship between lexical retrieval and syntactic production. Studies have reported changes in syntactic production across the lifespan, but their underlying cause remains unclear. In younger adults, it has been suggested that lexical factors, such as an item‟s semantic or phonological representation influence syntactic production; however, the full nature of this influence remains unclear. Studies investigating the type of sentence produced have found semantic facilitation and phonological interference (e.g., Bock, 1986, 1987), but studies investigating response time (e.g., Meyer, 1996) have found the opposite effects. This investigation sought to examine the influence of lexical level information on sentence production in younger and older adults. This was accomplished by concurrently examining reaction time and sentence type effects. In Experiment 1, 61 adults (mean age: 21.8 years) were presented with pictures and distractor words (unrelated, or semantically or phonologically related). Three stimulus onset asynchronies (SOA) were used (-1000ms, -150ms and 150ms). Participants were required to describe each picture. Using an analysis of variance, response time was compared across the different conditions and using generalized estimating equations, the type of sentence produced and the position of the primed word were compared. In Experiment 2, phonological distractors were excluded, and one SOA (-150ms) was used. Testing involved 83 younger adults (mean age: 22.9 years) and 56 older adults (mean age: 74.7 years). In Experiment 1, semantic distractors resulted in related nouns being produced more often in the subject position. This effect was observed in the analysis of the position of the target noun, but not in the analysis of the type of sentence produced. There were no effects of phonological distractors. In Experiment 2, semantic distractors influenced the type of sentence produced for both age groups. The groups differed only in error production. No reaction time effects were observed in either experiment. This investigation successfully demonstrated an influence of lexical level information on the syntactic productions of younger and older adults. The two groups were similar in their productions, suggesting that aspects of syntactic production are preserved in older adults.

The efficiency of human visual information processing is supported by numerous attentional resources. These resources ensure that behaviourally relevant information within visual scenes is selected for detailed processing, while behaviourally irrelevant information is ignored. One of these attentional resources—reflexive visuospatial attention—operates by prioritising locations in visual space in response to the appearance of salient stimuli. The purpose of the present dissertation was to examine how this type of attention contributes to the efficiency of visual processing by asking: How is processing altered for information presented at the location of attention? To develop some initial evidence of the stage of processing affected by reflexive visuospatial attention, Chapters 1 to 6 assessed whether this attentional resource is related to four other stimulus-driven effects that are each associated with a specific stage of visual processing: identity processing, object filtering, visual working memory (VWM), and response generation. Based on the observation that only the stimulus-driven effects on VWM are related to reflexive visuospatial attention (i.e., only those effects were contingent on attentional control settings), a VWM model of reflexive visuospatial attention was proposed in Chapter 7, and tested in Chapters 8 to 11. According to this model, reflexive visuospatial attention alters visual processing by triggering VWM to update. Thus, the effect of reflexive visuospatial attention is to speed the encoding of attended information into VWM. As a result, this information is more likely than unattended information to bias our behaviour, in particular those behaviours that depend on VWM. Further, by biasing VWM, reflexive visuospatial attention can interact with other attentional resources that have also been associated with VWM. In this way, these attentional resources can coordinate in optimising the process of selection, thus, contributing to the efficiency of the human visual system.

Children with fetal alcohol spectrum disorders (FASD) have deficits across many cognitive, behaviour and social domains. However, despite social difficulty being proposed as a main deficit following prenatal alcohol exposure, the nature of their deficient social behaviour is largely unknown. One process that may underlie difficulties in social functioning is poor social cognition, which refers to one’s understanding of the self, others and social world. The primary goal of this dissertation was to determine whether social cognitive deficits represent a core disability underlying the socio-behavioural problems of FASD using a bottom-up approach. The first level of this approach is represented by face processing. Global and independent face feature processing was compared between FASD and normal controls (NC) using experimental and clinical measures. Eye gaze processing was investigated next using experimental and clinical tasks. At the highest level of the bottom-up approach, social perspective taking, including theory of mind and empathy were examined, along with how these abilities related to parent-rated behaviour. Finally, the lowest level consisted of specific aspects of the social neural network. White matter in three limbic pathways was investigated using diffusion tensor imaging (DTI). Results generally supported the bottom-up approach of social cognition in FASD. These children showed impaired processing of face features, when matching mouth shapes and partially occluded identity, compared with NC. The FASD group was slower to process gaze and arrow cues, suggesting impaired attention shifting. Children with FASD also showed impairments in social perspective taking, including understanding false beliefs and empathy, and these impairments were related to parent-rated attention and social problems, and autistic-like traits. Deficits in theory of mind got worse with age in FASD and empathy showed distinct sex-related differences. Although no group differences were observed on DTI indices, groups did show different age-related changes in white matter. In conclusion, deficits at each level of the current bottom-up approach may underlie the social impairments in FASD and may contribute to their broader social behavioural phenotype. The results from this dissertation have potential to inform clinical practice and lead to more effective diagnostic and treatment approaches in FASD.

A language comprehension mechanism that immediately starts processing language as it is encountered is typically thought of as one that speeds and facilitates spoken language comprehension. However, there exist cases where the earliest parts of a word or phrase encode information that is somewhat at odds with the remainder of the word or phrase in full. Examples of these "potentially misleading" cases include compound words where the initial subpart of the compound belongs to a different syntactic category than the entire compound (e.g., "popcorn", "greyhound"), or noun phrases where the initial element of the phrase signals perceptual properties possessed by the referent of the noun phrase (e.g., some Chinese Cantonese classifier-noun phrases). Using a visual-world methodology, this dissertation explores the kinds of unintended or "impulsive" activation that are triggered when listeners encounter such cases, as well as how syntactic and contextual cues can constraining this impulsive activation. Experiment 1 examines whether hearing compound subparts (e.g., "pop-" in "popcorn") activates conceptual associates across syntactic categories, and Experiment 2 examines whether this activation is moderated by listeners' expectations about the syntactic structure of the sentences they encounter. Experiments 3 and 4 investigate the processing of compounds whose initial subparts correspond to colour terms (e.g., "greyhound"). Experiment 3 explores whether these colour subparts trigger the activation of phrasal-level descriptions of non-target objects in the visual display, and whether this activation is influenced by the presence/absence of motivation to use colour descriptions when naming screen objects. Experiment 4 further explores whether a perceptual mismatch between a target object and the colour term in its name increases this impulsive activation. Finally, Experiment 5 investigates whether listeners use the perceptual information encoded in pre-nominal classifiers in Cantonese Chinese to guide their consideration of referential candidates whose perceptual properties do or do not match the classifier semantics. The findings from this dissertation point to the highly interactive nature of spoken language comprehension, suggesting that the kinds of impulsive activation under current discussion are rampant and automatic, but can also be suppressed to varying degrees by the syntactic, semantic, and contextual cues available to the listener.

Substantial evidence indicates that maltreatment places abused children at great risk for illiteracy and damaging self-perceptions of competency and worth. Given that academic ability and self-concept are reciprocally related and mutually reinforcing, it was hypothesized that participation in an intensive literacy intervention would positively impact the reading, writing, and related self-perceptions of maltreated Struggling Readers from the Ontario Child-Welfare system. Using a mixed methods approach, 24 participants (ages 14-24) completed achievement and self-perception measures and were interviewed about their literacy experiences and views, pre and post intervention. Repeated measures analyses and pairwise comparisons measured the impact of intervention on the literacy skills and related self-evaluations of these youth and assessed how the literacy skills and related self-evaluations differed from maltreated youth without reading difficulties (n = 22). Interviews were analyzed thematically. Results converged to provide empirical support for the benefits of literacy intervention on skill and self-perception development for this high risk group of youth. Qualitative analyses further revealed unanticipated, dramatic and meaningful life changes. Participants manifested improved communication and metacognitive skills, increased autonomy and internal motivation, and amplified feelings of empowerment and hope for the future.

Paediatric posterior fossa tumors are often effectively controlled with a combination of radiation, chemotherapy and surgery. However, therapeutic craniospinal radiation has been associated with widespread cognitive late effects. Working memory is one such cognitive ability that has yet to be fully examined in this clinical population. Bilateral tracts connecting the cerebellum with the DLPFC were delineated using DTI tractography in all participants, replicating the cerebrocerebellar pathway outlined in an animal model. There were observable differences in white matter integrity (quantified by DTI measures of anisotropy, and mean, axial, and radial diffusivity) of the cerebellum-DLPFC pathway in patients versus controls. Additionally, working memory deficits that were found in patients were correlated with DTI indices pertaining to the cerebellum-DLPFC pathway. Therefore, this thesis is the first to explore the possible relations between white matter integrity of this pathway following treatment for paediatric posterior fossa tumors and working memory function.

Objectives: To demonstrate that at 6-months post-cessation of cognitive behaviour therapy (CBT) adapted for acquired brain injury (ABI), (1) patients maintain psychological benefits, (2) coping strategy selection improves, (3) community integration is enhanced, and (4) benefits are observed in both face-to-face and telephone administrations. Methods: Participants. Seventeen ABI patients with elevated psychological distress. Outcome Measures. Pre-treatment, post-treatment and 6-month follow-up performance on the Symptom Checklist-90-revised (SCL-90-R), Depression, Anxiety Stress Scales (DASS-21), Community Integration Questionnaire (CIQ) and the Ways of Coping-Revised Questionnaire (WOC-R). Procedures. Eleven CBT sessions provided in group, face-to-face format or individually by telephone. Results: For face-to-face and telephone groups, psychological distress was significantly reduced from pre-treatment to 6-months follow-up: DASS-21 (t16= 7.32, p <.000); SCL-90-R (t16= 6.22, p <.000). Community integration (t16= -6.15 p<.000) and problem-focused coping (t16= -3.67, p<.01) were also significantly enhanced. Conclusion: CBT adapted for patients with ABI carries robust benefits even 6-months after treatment.

This study investigated the neuroplastic changes that accompany speech identification training using magnetoencephalography (MEG). Participants completed three practice sessions over two consecutive days. In the morning group, practice occurred in the morning and evening of the first day, and in the morning of the next day; whereas, in the evening group, practice occured in the evening of the first day, and in the morning and evening of the second day. In both groups, behavioural improvement between the first session and last session was comparable. Neuromagnetic data showed practice-related changes in N1m amplitude between the first and last sessions. A time-of-day (TOD) of practice effect was found for P2m mean amplitude. In both groups, P2m-related changes with practice were greater when consecutive sessions occurred between days than within a day. The results are consistent with the proposal that task-related changes in the P2m wave are an index of perceptual learning.

Chronotype describes the daily rhythm of an individual’s performance capability as it changes through the day. It is defined using the Horne-Östberg Morningness-Eveningness Questionnaire (MEQ) which assesses time-of-day preference; or the Munich ChronoType Questionnaire (MCTQ) which indicates sleep timing parameters. My hypothesis was that chronotype predominantly reflects an individual’s perceived daily rhythm in executive function. We tested this by comparing MEQ and MCTQ with the University of Toronto Inventory of Morningness and Eveningness (UTIME) Questionnaire which examines performance on scenarios requiring cognitive, physical, and/or emotional responses. Highest correlations were found between MEQ and UTIME tasks with high executive demand. The same UTIME tasks were also correlated with MCTQ (mid-sleep, free days), although the correlations were consistently lower than UTIME versus MEQ. Correlations among UTIME tasks and MCTQ (mid-sleep, workdays) were not linked to executive demand. Chronotype appears to reflect the perception of peak executive ability independently of sleep pattern.

Knowledge of the literature pertaining to patterns of performance in normal individuals is essential if we are to understand intraindividual variability in neurocognitive test performance in neuropsychiatric disorders. Twenty-five healthy individuals with a high-level of education were evaluated on a short neuropsychological battery which spanned several cognitive domains. ---Results indicated that cognitive abilities are not equally distributed within a sample of healthy, high-level functioning individuals. This may be of interest to neuropsychologists who might base clinical inference about the presence of cerebral dysfunction, at least in part, on marked variation in a patient’s level of cognitive test performance. The practice of deductive reasoning in clinical neuropsychology may be prone to false-positive conclusions about cognitive functioning in neuropsychiatric disorders where base-rates of cognitive impairments are low and pre-existing educational achievements are high.