There is a dearth of studies investigating attention and cognitive executive functions (EFs) in adults with Attention Deficit/Hyperactivity Disorder (AD/HD), dyslexia, and AD/HD with comorbid dyslexia. Of the available studies, few have compared cognitive performance based on comprehensive theoretical models of attention and EFs and addressed methodological limitations of past research (e.g., sample inclusion and task validity confounds). This dissertation reports the findings from two studies which examined attention performance and performance pertaining to EFs and related cognitive processes of vigilance and processing speed for four groups of postsecondary students, those with AD/HD, dyslexia, AD/HD with comorbid dyslexia, and normal controls. Using a diagnostically referred sample to ensure distinct disability groups and attention and EFs measures with demonstrated construct validity, cognitive task performance was examined in Study 1 based on Posner and Raichle’s (1994) model of attention which is composed of alerting, orienting, and executive attention networks. In Study 2, Pennington and Ozonoff’s (1996) conceptualization of EFs that includes inhibition, set shifting, and working memory components was applied to the students’ performance on attention, EFs (inhibition, set shifting, and working memory), vigilance, and processing speed measures. Results from the two studies showed that the groups with attention deficits (AD/HD and comorbid groups) exhibited vigilance, executive attention, and EFs deficits related to inhibition and set shifting. The groups with reading impairments (dyslexic and comorbid groups) displayed a specific EF deficit in auditory working memory and a processing speed response time deficit. The common etiology hypothesis, which posits that cognitive deficits in comorbid groups are the sum of deficits found in AD/HD and dyslexia alone, best described the performance of the comorbid group. The results are discussed with respect to identification/assessment, compensatory strategies, and educational interventions in postsecondary students with AD/HD and dyslexia. The studies emphasize that comparing cognitive performance based on comprehensive theoretical models of attention and EFs and addressing sample inclusion and task validity confounds can effectively delineate cognitive deficits in adults with AD/HD and dyslexia. / Thesis (Ph.D, Education) -- Queen's University, 2011-09-26 12:27:59.503

The implementation of school-wide behavior supports is considered typical educational practice. A main component of school-wide behavior support is the systematic screening for behavioral and emotional problems. Students' ability to utilize executive functions greatly affects both academic and social success and it is associated with behavior and emotional problems (Lehto, Juujarvi, Kooistra, & Pulkkinen, 2003). This study uses a sample of fourth grade students to analyze the relationship between executive function skills and a screening measure of behavior. This study will examine if deficits in executive function may account for variance in the first level of behavior support screening systems. This may help educators understand the relationship between behavior screening results and executive functions, and possibly explain how social and emotional difficulties may be affected by deficits in executive functions. / School of Education / School Psychology / PhD / Dissertation

Although the paediatric literature in the area of executive function has expanded significantly over the past 20 years, there is still an imbalance of knowledge when compared to the adult literature. The present project sought to redress the balance in executive function research by (1) investigating the development of a wide range of executive processes in children between the ages of 3 and 7 years, and (2) examining the effects of early frontal lobe damage on the ongoing development of these skills.

No description available.

Reading comprehension is crucial for academic achievement. While word-level reading and oral language comprehension skills are well-established predictors of reading comprehension, emerging research has been investigating the role of executive function (EF) processes in reading comprehension. The role of shifting – one of the core EF processes – still is underexplored. The purpose of this study was to examine the relation between reading comprehension, shifting, and well-established components of reading comprehension in grade 3 students, across three different shifting tasks. Thirty-six children, ages 8 to 9 years, completed a collection of word-level reading, reading comprehension, receptive vocabulary and EF tasks (working memory and shifting). Results indicated that reading comprehension was significantly and moderately associated with all shifting tasks, word-level reading skills, and receptive vocabulary, but not with WM. In addition, each shifting task explained unique variance in reading comprehension after accounting for word-level reading skills. When receptive vocabulary was added to the regression analyses, shifting tasks did not explain significant variance in reading comprehension performance. Results of this study are discussed in relation to existing models of reading comprehension. / Graduate

The present study examined the neuropsychological relevance of poor sleep in a sample of community dwelling healthy older adults and a clinical sample of patients with untreated obstructive sleep apnea (OSA) between 40 and 90 years of age. The cognitive performance of 67 patients with obstructive sleep apnea (OSA) was compared to those of 46 controls screened for OSA using a portable device called ApneaLinkTM. The current study identified common neuropsychological variables associated with poor sleep quality in general (i.e., as a result of daytime sleepiness) and neuropsychological variables unique to only OSA patients (i.e., manifesting oxygen desaturation at night in addition to daytime sleepiness). Results indicated executive functions were related to hypoxemia and sustained attention was related to sleep fragmentation in the current study. A medical sequelae model and a neuropsychological sequelae model were tested. The neuropsychological sequelae model predicted whether one was a control or an OSA patient 70% accurately based on the predictors (scores on Wisconsin Card Sorting Test perseverance error, vigilance task, WAIS III forward digit span, WAIS III Block Design, phonemic and semantic fluency, and WAIS III backward digit span). The medical sequelae model predicted OSA status 89% accurately based on the predictors (BMI, depression, subjective sleep quality, age, hypertension, diabetes, total mood disturbance, gender, and general health). The current study provides further justification for OSA screening in the general population during middle age and late adulthood especially in those most at risk (i.e., overweight, male, hypertensive, and poor subjective sleep quality).

No description available.

Early childhood marks a time when word learning is accompanied by rapid growth in the cognitive processes that underlie self-modulated and goal-directed behavior (i.e., executive functions (EF)). Although there is empirical evidence to support the association between EF and vocabulary development in childhood, inconsistent findings have been reported regarding the extent to which early EF abilities predict later vocabulary outcomes and vice versa. Thus, the first aim of the present study was to employ a stringent analytic approach to examining the longitudinal relations between EF and vocabulary across multiple waves in early childhood (i.e., at ages 2, 3, 4, and 6). Among the studies that have documented a link between children's early and later EF/vocabulary skills, the underlying mechanism(s) that can account for this association have yet to be identified. As such, the second and third aims of this study were to investigate children's private speech and visual attention skills as potential mediators of the hypothesized link between early and later EF/vocabulary. The results indicate that after controlling for maternal education, a unidirectional cross-lagged panel model best fit the data. That is, across all measurement waves, children's vocabulary scores at one timepoint were positively predictive of their EF performance at the following timepoint. Although no evidence of mediation was detected, a significant and novel association emerged between children's early vocabulary scores and their later private speech production. Moreover, this study was able to replicate the well-established link between visual attention and receptive vocabulary among a sample of older children. / Doctor of Philosophy / Across the first few years of life, young children are quickly learning to understand/say new words (vocabulary development) at the same time that they are improving upon their ability to create plans, solve problems, and control their thoughts/actions (executive functioning (EF) development). These early skills act as developmental "building blocks" because they play an essential role in shaping more complex abilities later in childhood and even adulthood. Given their importance, the first goal of this study was to examine whether children's early abilities in one area are related to their later abilities in the other area at multiple ages across the early childhood period. For example, does vocabulary size at age 2 or age 3 relate to children's EF scores at age 3 or age 4? The results show that at each age measured in this study, children's early word knowledge predicted their later EF performance. The second goal of this study was to identify research-based, mediating variables in order to better understand why the expected association between vocabulary and EF exists in childhood. The results show that children with larger vocabularies at age 2 think out loud more when completing a difficult task at age 4, and that children who are skilled at finding requested objects when viewing a cluttered picture at age 4 have larger vocabularies at age 6. Collectively, these findings suggest that children's language and cognitive skills are closely related starting in toddlerhood and continuing into the elementary school years.

Episodic memory refers to context based explicit memory and shows vast improvements during middle childhood. In this study, episodic encoding was manipulated using stimuli that were hypothesized to require active or passive processing. Nine to eleven-year-old children were presented with a recall task using lower resolution (active processing) and clear (passive processing) images. It was hypothesized that children would recall more low resolution images than clear images. Executive function ability was also assessed to investigate possible contributions to performance. Furthermore, this study investigated whether frontal and temporal brain electrophysiology predicted unique variance in recall performance. Results suggested that overall there were no performance differences between low resolution and clear images; however, differences may exist within task blocks. Electrophysiology at temporal scalp locations and executive functions predicted unique variance in memory task performance. Specifically, set-shifting and working memory predicted a unique amount of variance in memory task performance. The results suggest that explicit memory may require certain executive processes more than others, and that active and passive processing may enhance this effect. / Master of Science

Completing activities of daily life relies on using both cognitive and physical resources efficiently, but these are affected by age. This may be due either to an age-related reduction in the resources we have available for carrying out tasks or to a reduction in our ability to use these resources efficiently. These resources comprise a set of processes called executive functions (EF), which collectively allow us to plan, initiate and monitor our performance of activities. Control and allocation of these resources is attributed to a central mechanism, sometimes called the central executive or executive attention, but the parameters that determine how resources are allocated are not well understood. Even simple or apparently automatic activities, such as walking, require attention, meaning that when task demands increase, for example when walking and speaking on the phone, there is a loss of efficiency in both tasks. The dual-task (DT) paradigm is an empirical means of examining the way attentional resources are allocated between two tasks by comparing their performance together in relation to how well they are carried out singly. Asking people to perform a cognitive task, such as counting backwards or spelling, while walking provides a reasonably naturalistic way to examine how flexibly older adults can divide their attention between the two tasks. Manipulating the demands of the task, either by increasing the difficulty of the cognitive task or instructing the participants to focus on one task or the other (prioritisation) should illuminate the strategies they use to allocate their available attention between the two tasks ask task demands vary. To explore this hypothesis a cohort of physically and cognitively healthy community-dwelling older adults (mean age = 72.3 years) took part in three studies. In the first experiment, 72 participants completed 8 single and dual-task conditions with varying cognitive load (counting back in 3s and 7s) and attention prioritisation (no prioritisation, prioritising walking and prioritising counting). Instructing the participants to prioritise walking in the DT when counting back in 7s produced the best walking and counting performance and this was predicted their score on a standardised measure of cognitive flexibility. In second part of the study, 68 of the participants were tested 12 months later when there was improvement in both their single and dual-task performances. There was also decline in concurrent walking and counting performance, but only when attention was allocated to walking in preference to the cognitive task. Both the improvements and the decline in performance after the 12-month period were predicted by a standardised test for EF at T1. In the third study a separate group of older adults (73.2 years) was trained to walk rhythmically to music, to further investigate the external manipulation of resource-allocation during concurrent walking and counting. Their performances were compared to 2 control groups who did not receive the same intervention procedures. Overall findings from this doctoral research demonstrate that explicitly manipulating attention-allocation during concurrent walking and cognitive activity improved healthy older adults' walking and counting performance and this was strongly associated with better cognitive flexibility. After 12 months, subtle decline in ability to allocate attention to walking during the DT, when attentional-demands were high, was also predicted by cognitive flexibility in an EF task. Together, these findings illuminated the role of executive attention in a rapidly-changing complex task when the ‘wrong' prioritisation could result in a fall. Observing healthy older adults' cognitive flexibility in allocating attention to walking, when required, revealed that executive attention was key to the future maintenance of their current functional well-being.