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Parallel systems have been widely adopted in the field of machine translation, because the raw computational power they offer is well suited to this computationally intensive task. However programming for parallel hardware is not trivial as it requires redesign of the existing algorithms. In my thesis I design efficient algorithms for machine translation on parallel hardware. I identify memory accesses as the biggest bottleneck to processing speed and propose novel algorithms that minimize them. I present three distinct case studies in which minimizing memory access substantially improves speed: Starting with statistical machine translation, I design a phrase table that makes decoding ten times faster on a multi-threaded CPU. Next, I design a GPU-based n-gram language model that is twice as fast per £ as a highly optimized CPU implementation. Turning to neural machine translation, I design new stochastic gradient descent techniques that make end-to-end training twice as fast. The work in this thesis has been incorporated in two popular machine translation toolkits: Moses and Marian.

Literature Review Background: Mathematical and reading abilities are predictive of academic achievement. To date, limited research has examined the relationship between processing speed and academic achievement in typically developing children. Greater insight into this relationship could help to identify the impact that reduced processing speed may have on long-term academic achievement. This review aimed to explore the relationship between these variables in typically developing children. Method: Studies conducted in the past twenty years measuring mathematics and/or reading abilities and processing speed in typically developing children using a standardised assessment measure were included in the review. In total 1278 studies were screened, which led to the identification of eight eligible studies that were included in the review. Results: No relationship was found between processing speed and reading ability. The findings on mathematics abilities were conflicting, with some studies identifying a relationship and other finding no significant association between these variables. Age appeared to be a moderating factor in studies that reported a significant relationship between mathematics and processing speed. Conclusions: The findings suggest that the relationship between processing speed and academic achievement is complex and the following review was unable to ascertain the direct relationship between these variables. It is recommended that future research examines the relationship between age and academic achievement in further detail. Empirical Paper Processing speed interventions have been found to be acceptable in children; however, there is limited evidence that they are effective in this population. This study investigated whether a processing speed intervention was effective in improving processing speed (PS) in children with suspected white matter disorders. The study hypothesised that children would demonstrate improvement on a daily outcome measure and between pre-baseline and post-intervention measures of PS. A single case experimental design utilising a multiple baseline approach was used to observe the effect of the intervention within and across participants. Three participants were recruited, each completing a choice reaction time (CRT) task three times a week that acted as the outcome measure. The processing speed intervention involved playing single player, multiplayer and iPad/android games. Overall there was no significant change in CRT between phases; however two participants demonstrated a medium effect size. There was no significant change in pre- or post-PS measures but there was evidence of reliable change in overall and cognitive fatigue. These findings suggest that the processing speed intervention was not effective in improving PS abilities. This paper highlights a number of challenges in implementing a processing speed intervention and explores the clinical implications of these findings.

Goal maintenance is the ability to keep task rules active in-mind so that they can guide behaviour. When this process fails, individuals are unable to use task rules appropriately, and consequently perform poorly on the given task. The rate of goal neglect has been shown to increase with the complexity of the information to be maintained, especially for those with low levels of fluid intelligence. The main aim of this thesis was to examine whether this effect arises from the limited capacity for task rules, the limited ability to cope with competition between task rules, or the limited ability to sustain maintenance of a rule over time both in younger and older adults. A second aim was to investigate whether fluid intelligence and processing speed contribute to performance when goal maintenance is taxed. In particular, the number of instructions presented at the start of the task (Experiments 1-4), the speed at which rules had to be used (Experiment 5), the infrequency with which a task-relevant goal was used relative to a task-irrelevant goal (Experiment 6), and the duration for which rules had to be maintained (Experiment 7) were manipulated. Finally, the importance of goal maintenance in a more real-world setting was examined by testing the relationship between goal neglect and academic performance in children (Experiments 8 and 9). Goal maintenance was not limited by the number of rules to be held in mind, but goal neglect did increase as the degree of competition between rules and the duration with which they were maintained increased. Fluid intelligence accounted for little of the variation in goal maintenance abilities, but processing speed played a moderating role in older adults. In terms of academic performance, goal maintenance in school-aged children significantly predicted mathematics abilities, but not language.

Adolescent and young adult survivors of pediatric brain tumors often live with long-term neuropsychological deficits, found to be related to functional and structural brain changes associated with the tumor itself as well as treatments such as radiation therapy. The importance of brain networks has become a central focus of research over recent decades across neurological populations. Graph theory is one way of analyzing network properties that can describe the integration, segregation, and other aspects of network organization. The existing literature using graph theory with survivors of brain tumor is small and inconsistent; therefore, more work is needed, particularly in survivors of pediatric brain tumors. The present study used graph theory to determine whether functional network properties in this population differ from healthy controls; whether graph metrics relate to core cognitive skills: attention, working memory, and processing speed; and whether they relate to a cumulative measure of neurological risk. 31 survivors and 31 matched controls completed neuropsychological testing and functional magnetic resonance imaging. Neuroimaging was preprocessed and spatially constrained ICA was completed, followed by calculation of area under the curve values of graph metrics. Results revealed a significant difference such that brain tumor survivors exhibited less small-world properties in their functional brain networks. This was found to be related to working memory, such that less small-worldness in the network was related to poorer performance. There were no significant relationships with neurological risk, but there were nonsignificant correlations of small-moderate effect size such that lower global efficiency and clustering coefficient were associated with greater neurological risk. Comparisons to structural network analysis from a similar sample and additional post-hoc analyses are also discussed. These findings reveal that survivors of pediatric brain tumor indeed display significant differences in functional brain networks that are quantifiable by graph theory. It is also possible that with further work, we might better understand how metrics such as small-worldness can be used to predict long-term cognitive outcomes and functional independence in adulthood. This would ideally allow neuroimaging to play a part in determining the most efficient and impactful allocation of intervention resources among pediatric brain tumor patients.

ADHD is a heterogeneous disorder that is highly impairing. Early, accurate diagnosis maximizes long-term positive outcomes for youth with ADHD. Tests of executive functioning (EF) are potential tools for screening and differential diagnoses for ADHD; however, previous research has been inconsistent regarding the specificity and magnitude of EF deficits across ADHD subtypes. Here we overcome these limitations by: (1) employing more rigorous methods to conceptualize ADHD in a way that better captures heterogeneity of expression, and (2) by applying a more comprehensive, reliable battery of EF tasks to this association. We tested 1548 children and adolescents (ages 7-15 years) from the Texas Twin Project, a population-based cohort with a diverse socioeconomic and ethnic composition. EF and processing speed were measured in-laboratory with a comprehensive test battery, while ADHD and sociodemographic characteristics were assessed via parent report. We show that EF deficits are isolated to the inattention domain of ADHD. Moreover, we found that the association between EF task performance and inattention remains stable across sociodemographic groups. Our results demonstrate that failures of executive control are selectively manifested as covert inattentive symptoms, such as trouble with organization, forgetfulness, and distractedness, rather than overt symptoms, such as inappropriate talkativeness and interruption. We anticipate that EF tests could be widely useful in clinical and educational settings due to their specificity regarding particular subtypes of ADHD behaviors and their broad predictive validity across key demographic subgroups

Problem Many studies suggest that Processing Speed (PS), Attention, and Working Memory (WM) are major cognitive functions that collaborate to achieve a coherent cognitive system. The aim of the current study was to improve the conception of how these cognitive functions interrelate. The study addressed two main questions: the first, whether PS can be predicted by WM (visual, verbal, and the central executive) and attention of elementary students in first and fifth grade; the second, whether there are gender differences in the rate of change in WM and PS from first to fifth grade. Method The participants were taken from a longitudinal study (n = 145, 71 boys) by Li and Geary (2017). In the study, students' WM was assessed by the Working Memory Test Battery for Children, PS was assessed by Rapid Automatic Naming, and attention was assessed by Strength and Weaknesses of ADHD—Symptoms and Normal Behavior (SWAN). The current study used canonical correlations and MANOVAs to answer the research questions. Results Overall correlations between the processing speed in fifth grade and working memory in first grade and attention was statistically significant (Wilks’ Lambda = .78, F(8, 278) = 4.61, p < .001, Rc2 = .17). Attention was a significant predictor (Beta = -.19, p = .024) of processing speed of number in fifth grade. The central executive in first grade (Beta = -.36, p =.001) was also a significant predictor of the processing speed of number in fifth grade. Correlations between processing speed in fifth grade and working memory in fifth grade and attention was statistically significant (Wilks’ Lambda = .80, F (8, 278) = 4.11, p < .001, Rc2 = .19). Visual working memory in fifth grade (Beta = -.21, p = .017) was the only significant predictor for processing speed of number in fifth grade. In terms of gender differences in the rate of change in working memory and processing speed from first to fifth grade the multivariate effect of gender was not statistically significant in which working memory (Wilks’ Lambda = 0.98, F(3, 141) = .54 p = .65) and processing speed (Wilks’ Lambda = 0.98, F(2, 1412) = 1.29 p = .65). Conclusions The central executive and attention in fifth grade were the best predictors of processing speed performance in fifth grade. However, in fifth grade the role of these cognitive functions in predicting processing speed shifted in which only visual working memory was the best predictor.

Theoretical models of ADHD often implicate executive function difficulties, particularly inhibitory control, as underlying ADHD symptoms. However, this theory has been challenged by studies showing that only a portion of children with ADHD have deficits in executive function. Processing speed has been suggested as a cognitive endophenotype of ADHD due to shared genetic and neurobiological etiologies with relevant symptom patterns. Indeed, children with ADHD often demonstrate slower processing speed than comparison children. It may be that “lower order” cognitive deficits in processes such as processing speed are crucial with respect to the long-term impairments of children with ADHD.The purpose of the present investigation was to examine (1) processing speed differences between ADHD presentations, (2) the relation between processing speed and ADHD symptomatology, (3) the relation between processing speed and academic achievement, and (4) the relation between processing speed and adult educational and occupational outcomes in a sample of girls with ADHD and their typically developing counterparts.The present study comprises secondary data analysis from 228 participants in a longitudinal investigation of females with and without ADHD (i.e., combined or inattentive presentations). Girls participating in the original study were between the ages of six and 12 years and participated in summer enrichment programs. In addition to the original data collection, three follow-up studies were conducted at five-year, 10-year, and 16-year follow-up intervals, with excellent subject retention, during which participants, caregivers, and teachers completed evaluations, including objective tests of academic performance.In conclusion, findings from the present study demonstrate an association between processing speed and concurrent inattentiveness in girls with ADHD. These findings also demonstrated a long-lasting association between slow processing speed in childhood and poor math performance from childhood through adulthood regardless of diagnostic status. Aside from the association with inattentiveness, slow processing speed does not seem to put girls with ADHD at particular risk for poor academic outcomes through childhood, adolescence, or adulthood. This may be attributable to sex differences in processing speed, such that females tend to have faster processing speeds than males. Indeed, this may be a protective factor of sorts for girls with ADHD. This may also mean that girls may benefit from targeted intervention in deficits other than processing speed. However, it was found that for all girls, regardless of diagnostic status, slow childhood processing speed predicts poor math performance through childhood, adolescence, and adulthood.

Background – Radiation therapy (RT) is a very common treatment for pediatric brain tumors. Unfortunately, RT is associated with long-term cognitive impairments. White matter (WM) tracts, such as the corpus callosum (CC), mediate processing speed which , in turn, mediates overall cognitive ability. Pediatric RT patients experience WM deficits and long-term deficits in processing speed and intelligence quotient (IQ). However, long-term effects of RT on WM integrity in these patients are unknown. Patients who receive RT frequently undergo surgery, but it is unclear how surgery affects long-term WM integrity and cognitive ability. WM integrity, age, gender, highest parent education and occupation, and family income are affecters of intelligence, but their effects on cognitive ability in pediatric RT patients are unknown.Objective - 1) to determine the long-term effects of RT on CC integrity as well as processing speed and IQ two years after treatment while controlling for surgery; 2) To determine the effects of non-treatment, intelligence-associated factors on post-treatment cognitive ability; 3) to quantity the relationship between radiation dose and WM integrity in pediatric brain tumor patients.Methods –Diffusion tensor imaging (DTI) was used to quantify WM integrity of the genu (GCC), body (BCC), and splenium (SCC) of the CC. Preschool, child, and adult variants of the Wechsler intelligence assessments measured processing speed and IQ. Participants included pediatric brain tumor patients diagnosed between 3 and 16 years old. They underwent baseline evaluations 3 to 12 months after surgery, and approximately two years later. Participants treated with surgery and RT were matched to those who didn’t receive RT. Baseline and two-year DTI, processing speed, and IQ data were compared between groups at each time point and to each other within each group. Along with RT status, factors including baseline BCC integrity, age, gender, highest parent education and occupation, and family income were evaluated as predictors of change in processing speed and IQ. Correlations were carried out between biologically corrected doses and WM integrity. Results – Compared to the no-radiation group, the radiation group exhibited significant reductions in BCC integrity at two years. The no-radiation group displayed a significant reduction in processing speed, compared to the population average, at baseline and both groups did so at two years. While neither group exhibited significant changes in IQ, compared to the population mean, at either time point, a significant temporal reduction in IQ occurred in the radiation group. Baseline WM integrity of the BCC, age at diagnosis, highest parent education, and family income significantly predicted processing speed change. No significant correlations were observed between biologically corrected doses and WM integrity.Conclusion - Pediatric brain tumor patients treated with RT may be at greater risk of experiencing long-term damage to the BCC than those treated without RT. All patients are at risk of experiencing processing speed deficits and radiation patients are at risk for significant temporal reductions in IQ. Lastly, non-treatment factors such as WM integrity, age, highest parent education, and family income may be more important predictors of processing speed change than radiation status.

While it is generally assumed that learning difficulties are the antecedent to affective problems, little is known about whether the reading-emotion association is bidirectional. If learning problems give rise to affective problems, then a subsequent question is whether affective problems, in turn, exacerbate reading difficulties. The purpose of the present study is to examine whether affective problems (i.e., anxiety, depression) predict unique variance in a critical reading skill (i.e., rapid automatized naming) above and beyond cognitive processing speed and basic reading skills (i.e., isolated word recognition, pseudoword reading) within a sample of adults referred for learning difficulty (M = 25.97 years; SD = 9.4). Based on extant literature, it was hypothesized that affective processing would predict variance in rapid automatized naming (RAN) above and beyond control variables (i.e., cognitive processing speed, basic reading skills). Such an observation will broaden our understanding of the bidirectional relation between reading and affective processing. We used three hierarchical regressions to examine the contributions of cognitive and affective variables to each of the following RAN skills measured by RAN/RAS (Wolf & Denckla, 2005): (1) RAN-Object/Color, (2) RAN-Number/Letter, and (3) RAS/2-3Set. Participants completed all RAN/RAS subtests (RAN/RAS: Wolf & Denckla, 2005), the processing speed cluster of the Woodcock-Johnson Tests of Cognitive Abilities III (WJ-III COG: Woodcock, McGrew, & Mather, 2001a), the basic reading skills cluster of the Woodcock-Johnson Tests of Achievement III (WJ-III ACH: Woodcock, McGrew, & Mather, 2001b), and anxiety and depression subscales of the Personality Assessment Inventory (PAI: Morey, 1991). Results from the hierarchical regression analysis showed that affective variables predicted significant variance in RAS/2-3Set (i.e., 16.8%), above and beyond contributions from cognitive processing speed and basic reading skills. Affective variables did not predict variance in any other RAN variable (i.e., RAN-Object/Color, RAN-Number/Letter). This finding is particularly notable because the RAS/2-3Set subtest is unique from the other two RAN subtests insofar as it includes an executive functioning component (e.g., mental set shifting). Contrary to our hypothesis, affective predictors did not account for unique variance above and beyond processing speed and basic reading skills in all RAN subtests. However, because affective predictors did account for such variance in the RAS/2-3Set subtest, it suggests that executive functioning plays a unique role in linking affective processing with reading. Broadly, present results suggest that affective processing may exert its effect “bidirectionally” onto reading when executive functioning is employed.

Adult survivors of childhood posterior fossa tumors can experience reading difficulties related to white matter integrity. Previously, reading was shown to be related to cortical white matter tracts, however information transfer across the corpus callosum (CC) may also play a role in reading. The current study used both macro- and microstructural measures of the WM structure of the corpus callosum. The current study examined how white matter volume and fractional anisotropy (FA) in five divisions of the CC was related to degree of neurological risk and reading skill, and tested two mediation models predicting reading. Participants included 20 adult survivors of childhood posterior fossa tumor and 23 healthy controls. Volume and FA were measured in five divisions of the mid-sagittal corpus callosum. Total intracranial vault was used as a covariate in volume analyses. FA was reduced in CC1 and volume was reduced in each subregion in survivors. Volume but not FA was related to degree of neurological risk. Results identified that reduced volume in CC1 and CC5, and FA in CC5 appear to be specifically related to reading skill in line with the cortical reading regions that connect in these subregions of the CC. Mediation models indicate that processing speed is the mechanism by which volume is related to reading skill. These findings have implications for addressing processing speed in reading interventions in survivors and provide insight into the interhemispheric connections in the reading network.

Recent evidence shows that high levels of prolonged sitting is negatively correlated with increased all-cause mortality. Moreover, it appears that physical activity may not negate this risk. Not only does musculoskeletal pain and discomfort impact employee health, but the cost to employers and the larger economy is great. The introduction of standing desks into the workplace offers a potential solution to this inactivity problem, and, therefore, it is logical to enquire about the effects of standing on cognitive performance. Processing Speed is a main component of cognition and is correlated with general measures of intelligence. Understanding the effects that standing desks have on Processing Speed can grant insight into the effects of these desks on general cognitive performance and resulting work output. A cross-over design was used to investigate the effect of a standing desk compared with a seated desk on Processing Speed during a simulated “work” day. Thirty healthy participants (14 female, 16 male), aged between 20 and 49 years old, were recruited to complete a battery of cognitive tasks over two 7.5 hour long sessions, one session of standing and one of sitting. The battery of cognitive tasks included four tasks testing Processing Speed. Three of the tasks, Symbol Search, Cancellation, and Coding were derived from the Wechsler Adult Intelligence Scale (WAIS-IV) tests of cognition, and the fourth task was derived from the Woodcock-Johnson III test of cognitive ability. A two-way repeated measures analyses showed that Processing Speed was not affected by standing when compared to sitting. A trend toward significance was found in the Coding task, revealing better performance in Processing Speed when standing. The results of this study provide evidence to suggest standing desks can be implemented into the workplace without causing reductions in Processing Speed and may, in fact, be beneficial. Because sitting for prolonged periods is harmful to physical health and incorporates large health costs, employers should consider standing desks as an alternative to sitting desks that could improve workplace health, and thereby reduce the associated costs without effecting an important aspect of cognition.

Past research has supported the idea that self-regulation uses a limited resource which is subject to depletion (Hagger, Wood, Stiff, & Chatzisarantis, 2010). Depletion has generally been measured by the reduced accuracy of task performance on one executive function task that follows another executive function task. The current study used two measures of time within a speech processing task to explore the effects of depletion on complex speech processing. Half of the participants completed the speech processing task before an inhibitory writing task (Group A), and the other half of the participants completed the inhibitory writing task before the speech processing task (Group B); Group B was therefore predicted to be depleted in their ability to complete the speech processing task relative to Group A. During the speech processing task, participants listened to sentences from two different speakers simultaneously, one a native speaker of English and the other a non-native speaker of English. Listeners were visually cued to listen to and repeat one speaker or the other in a random sequence. After repeating each sentence, participants were given a forced choice question requiring them to identify the sentence spoken by the target speaker. The forced choice answer set provided two answer choices, the sentence spoken by the native speaker of English and the sentence spoken by the non-native accented speaker of English. Answers to these forced choice questions were used to verify whether participants had attended to the correct target. The current study analyzed response times for the forced choice questions (FCR) as well as the self-paced advancement (SPA) times (the times the participants waited before progressing from item to item). Times were analyzed for each participant and as means across participants between the two experimental groups. Results indicated no significant group differences for either forced choice response (FCR) times or self paced advancement (SPA) times. Regression analyses revealed a trend of decreasing SPA time over the course of the experiment but no trends were observed for FCR time. These results indicate a lack of depletion effects on measures of FCR and SPA time and the possible effect of increasing automaticity on the SPA time measure.

Performance deficits on cognitive tasks have been demonstrated consistently in depressed and anxious individuals. Processing efficiency theory asserts that these deficits might be accounted for by task-irrelevant processes, including the negative impact of rumination. This study was designed to better understand the relationship between cognitive deficits and depression by creating a ruminative state in healthy control subjects to determine if they would exhibit performance deficits similar to those observed in patients with depression. Specifically, the effect of rumination induction on select subtests of the Wechsler Adult Intelligence Scale – Fourth Edition (WAIS-IV) was examined. Participants were college students with no current depression, anxiety, ADHD, or substance abuse disorders, who also are not currently taking psychoactive medications or receiving psychotherapy. Participants were randomized to a rumination or distraction condition and administered subtests from the WAIS-IV hypothesized to be most affected by rumination and depression. Controlling for test, math, and trait anxiety, as well as pre-experimental rumination, individuals in the rumination condition performed more poorly on one subtest within the processing speed domain, as well as on the Processing Speed Index score. These results support the processing efficiency model of cognitive deficits in depression, suggesting that rumination induction interferes in the efficient completion of mental tasks. Future research can build on these findings by studying this model in a clinical population and by continuing to improve the effectiveness of mood induction tasks for research on the effects of this widespread and significantly impairing disorder.

Delay discounting, the belief that rewards decline in value over time, is a phenomenon observed in several clinical disorders, including Attention Deficit / Hyperactivity Disorder (ADHD), substance abuse disorders, and other impulse control disorders. Delay discounting behavior is characterized by a tendency to choose smaller, more immediate rewards over larger, more delayed rewards. This tendency has been associated with behavioral impulsivity and inability to delay gratification observed in the aforementioned clinical disorders. It has been suggested that time perception may be a salient feature of delay discounting. If the larger, longer-term reward is perceived as being more temporally remote, its relative value decreases and is associated with greater cost, and one becomes more likely to choose the more immediate reward over the longer-term (though optimal) choice. Time perception has been studied in clinical populations, with increased variability of responses as well as both under-production and overestimation of time intervals observed in those with ADHD and other disorders associated with impulsivity. The present study used informational feedback via a metronome to change belief regarding duration of a second--either increasing or decreasing it by approximately 20%. Participants were 132 college-aged students with and without a diagnosis of ADHD. Measures of impulsivity and ADHD symptomatology were collected as well, and participants completed several cognitive tasks measuring working memory and processing speed to explore the impacts of these measures on delay discounting and time perception. While participants were able to reliably incorporate the altered second belief into short estimations of time (i.e., less than a minute), the manipulation failed to generalize to longer-duration temporal estimations, and it did not affect delay discounting. Neither ADHD symptomatology, impulsivity, nor performance on the cognitive tasks were related to delay discounting behaviors, though a working memory measure was correlated with baseline (pre-manipulation) time and one longer duration estimation. This lends support to a relationship between working memory and temporal perception, though the relationship between temporal perception and delay discounting remains elusive. Directions for future studies to clarify the role of temporal processing and ADHD in delay discounting are discussed.

The purpose of this study was to investigate the relationship between word reading and white matter (WM) integrity in the reading system and test a theory-based moderated mediation model such that relationship of WM integrity with word reading is mediated by processing speed and indirect effect is moderated by group. Thirty-seven adult survivors of childhood brain tumor and typically developing adults participated (mean age=24.19(4.51) years, 62% female). Tractography identified the WM tract for three reading system connections. Fractional anisotropy of the IFOF and PT-OT tracts were significantly correlated with word reading in survivors (r=.55, .46, respectively; p

This study examined processing speed and executive function late effects in survivors of pediatric ALL (hereafter referred to as Survivors). Late effects are long-term, treatment-related health problems associated with the neurotoxic side-effect of cancer treatment on brain development. Processing speed —mental and motor speed with which a person can solve nonverbal problems — was estimated via an composite of processing speed attained from several measures of processing speed. Executive function — a collection of processes orchestrated in the performance of purposeful, goal-directed behavior — was measured using the Parent and Teacher forms of the Behavior Rating Inventory of Executive Function (BRIEF). This study also explored the effect of previously identified risk factors for processing speed and executive function late effects. Finally, executive function late effects were further explored via the use of performance-based measures, including the Tower and Trail Making (Condition 4) tests of the Delis-Kaplan Executive Function System (D-KEFS). Hypotheses included (1) Survivors would demonstrate significantly poorer processing speed; (2) late effects risk factor variables (i.e., greater elapsed time since completion of treatment, lower age at diagnosis, and higher intensity of treatment) would predict poorer processing speed; (3) female gender would predict poorer processing speed; (4) parents and teachers would demonstrate both low interrater agreement (Hypothesis 4a) and differ significantly in the severity (Hypothesis 4b) of their ratings of Survivor executive function; (5) parent and teacher ratings of executive function would indicate significantly poorer Survivor metacognition (Hypothesis 5a), whereas Survivor behavioral regulation would not differ significantly (Hypothesis 5b); (6) risk factor variables would predict poorer Parent and Teacher ratings of Survivor metacognition; (7) female gender would predict poorer Parent and Teacher ratings of Survivor metacognition; (8) survivor processing speed and Parent and Teacher ratings of executive function would exhibit a positive relationship; and (9) poorer Survivor processing speed would predict poorer parent and teacher ratings of executive function. Results provided support for hypothesis 1 and 5a. Partial support was obtained for hypotheses 4a, 4b, and 7. Hypotheses 2, 3, 5b, 6, 8, and 9 were not supported.

Objective: To identify neurobehavioral and neurocognitive predictors of impaired behavioral functioning after adolescent traumatic brain injury (TBI). Design: Multicenter cross-sectional study. Setting: Outpatient. Participants: 132 primary caregivers and children age 12-17 years who sustained a moderate or severe TBI within the past 1-6 months. Primary Measures: Self and parent ratings of executive function (EF), tests of memory and processing speed (PS), and a structured clinical interview of behavioral functioning. Analysis: Logistic regression was used to examine associations of behavioral functioning with ratings of EF and tests of memory and PS. Results: Caregiver ratings of problems in EF were associated with global behavioral functional impairment (OR 1.11 [95% CI: 1.05, 1.17], p

A significant subset of mild traumatic brain injury (mild TBI) and chronic pain (CP) patients report, and sometimes show objective evidence of, persisting cognitive problems. Despite differences in injury mechanisms, there is considerable overlap in the types of persisting cognitive symptoms that are reported by the two populations. Psychogenic, rather than physiogenic, factors are thought to play an important role in the maintenance of these persisting symptoms. The current investigation examined the contributions somatization, depression, and anxiety had on an objective measure of “working attention.” In order to best elucidate the influences these psychological factors had on attentional performance, only individuals who passed well-validated and popular indicators of cognitive and self-report validity were included in the study. Two hundred and forty-nine individuals (n = 116 TBI; n = 133 CP) met the inclusionary criteria for the study. Psychological factors were assessed using Scales 1 (Hypochondriasis), 2 (Depression), 3 (Hysteria), and 7 (Psychasthenia) of the Minnesota Multiphasic Personality Inventory-II. “Working attention” was measured using the demographically-adjusted T-scores for the Working Memory and Processing Speed Indexes of the Wechsler Adult Intelligence Scale- 3. Results indicated that a high rate of psychological complications was observed in the mild TBI and CP groups but not the moderate-severe traumatic brain injury (M/S TBI) comparison group. Analysis indicated that psychological elevations were not significantly related to spontaneously-reported symptoms or working attention deficits for the mild TBI group but were for the CP and M/S TBI groups. The current results are important for understanding the psychological complications that may occur in individuals exhibiting persisting cognitive problems in these clinical populations.

Learning and memory impairments are among the most common and enduring cognitive consequences of traumatic brain injury (TBI). Researchers have yet to reach a consensus with regard to the basic cognitive mechanism underlying new learning and memory disturbances after TBI. The purpose of the present study was to investigate the current views regarding the cognitive processes thought to explain impairments in verbal learning and memory subsequent to brain injury. Specifically, this study sought to examine the roles of the central executive component of working memory and processing speed in verbal learning ability following TBI. Latent variable structural equation modeling (SEM) was used to analyze the data of 70 post-acute care TBI patients between the ages of 16 and 65, who completed a full neuropsychological evaluation. Results indicated that verbal learning and memory difficulties following TBI were explained primarily in terms of the central executive aspects of working memory, after accounting for the relative contributions of processing speed in the model. The direct effect of processing speed on verbal learning and memory was not significant when working memory was taken into account in the model. Rather, the effects of processing speed on verbal learning ability were largely indirect through the central executive component of working memory. Results highlight the importance of both working memory and processing speed in supporting verbal learning and memory processes after TBI. Practical implications for targeting remediation efforts and directing approaches to memory rehabilitation are discussed in light of the study’s findings.

People use facial appearance to infer the social attributes of others. A primary indicator of facial attractiveness is prototypicality (the proximity of an object to its categorical central tendency); faces and objects closer to the central tendency are judged as more attractive. Perceptual fluency theory suggests that cognitive processing speed directly generates positive affect. This dissertation examined the relationships among attractiveness, prototypicality, and affective response in faces and non-face objects across adult and 8-year-old participants using a reaction time (RT) paradigm. RT predicted positive affect and disgust responses to facial stimuli. Of particular note are the series of complementary findings suggesting that reaction to unattractive faces may be both quantitatively (i.e., longer RT latencies) and qualitatively (i.e., judged to be less typical) different from high and medium attractive faces. These findings may help explain how appearance-based stereotypes are formed and maintained.

Mitochondrial Diseases (MD) are disorders of function in cellular oxidative phosphorylation caused by diverse nuclear DNA and mtDNA mutations and seen in 1/5,000 births.  The purpose of this study was to examine relationships across medical indices, biochemical measures, and neurobehavioral functioning in children with MD.  Findings from Western Blot, Native Gels, High Resolution Respirometry, and the Nijmegen diagnostic criteria were assessed in relation to children’s processing speed and attention, based on the prediction that impaired functioning of proteins, complexes, and cellular respiration, that are critical in ATP production, will impact neurodevelopment and related neuropsychological processes in children with MD.  Twenty-five children (ages 4-13) were administered subtests from the DAS-II and NEPSY-II.  Results from multiple regression analyses suggest that processing speed and attention deficits may be markers of abnormal protein expression that interferes with the production of ATP in the oxidative phosphorylation process; implications for future research are presented.

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most commonly diagnosed of child clinical syndromes and is associated with poor academic achievement, poor peer and family relations, and an elevated risk for anxiety, depression, and conduct disorder (Barkley ,1990; Barkley, Guevremont, Anastopoulos, DuPaul, & Shelton, 1993; Barkley, Murphy, & Kwasnik, 1996; Beiderman, Faraone, & Lapey, 1992; Fischer, Fischer, et al., 1990; Hinshaw, 1994; Nadeau 1995; Weiss & Hechtman, 1993). Although ADHD is one of the most commonly diagnosed and widely researched disorders, the diagnostic criteria and defining characteristics of ADHD remain controversial (Wolraich, 1999). The current diagnostic formulation, as specified by the DSM-IV-TR, includes three distinct subtypes: Attention Deficit Hyperactivity Disorder- Predominantly Hyperactive Impulsive Type (ADHD-H), Attention Deficit Hyperactivity Predominantly Inattentive Type (ADHD-PI) and Attention Deficit Hyperactivity Disorder- Combined Typed (ADHD-C). Perhaps the most controversial aspect of the current nosology is the inclusion of the inattention symptoms within the family of ADHD diagnoses (Milich, Balentine, Lynam, 2001). Researchers and clinicians have further posited that ADHD-PI represents a distinct disorder with two subtypes: inattentive-disorganized and sluggish cognitive tempo. This study explored the relation between reading fluency, sluggish cognitive tempo symptoms, disorganized symptoms, processing speed and ADHD diagnosis. This study examined performance of children diagnosed 77 children diagnosed with ADHD (i.e. 53 participants met criteria for ADHD-PI and 24 participants met criteria for ADHD-C) on measures of cognitive functioning, processing speed, behavioral reports, sluggish cognitive tempo, disorganization and reading fluency. Significant group differences did not emerge on measures of processing speed, sluggish cognitive tempo symptoms or disorganized symptoms. Path analysis was employed to examine the simultaneous effects of processing speed on inattention symptoms, hyperactive/impulsive symptoms, SCT symptoms, DO symptoms, reading fluency, and internalizing symptoms. In addition, the paths from SCT symptoms, DO symptoms, inattention symptoms, and hyperactive/impulsive symptoms to reading fluency and internalizing symptoms were also be examined. Processing speed had a significant direct effect on SCT symptoms, Inattention Symptoms and Reading Fluency. In addition, SCT symptoms had a significant direct effect on anxiety symptoms. In summary, findings from the study provide important information about the link between processing speed, attention written, and reading fluency. Limitations of the study and implications for future research and practice are discussed.