Inhibitory control is vital to typical development and matures rapidly throughout early childhood. Inhibitory control deficits are seen in both autism spectrum disorders and attention-deficit/hyperactivity disorder and, along with other executive functions, inhibitory control contributes to school success. The tasks used to measure and stress these skills in children have not been fully explored. Even given the cognitive development levels of young children, the current inhibitory control tasks for preschoolers are not completely comparable to the tasks used with adults. For my thesis study, I added a mixed condition to the day/night inhibitory control task in preschool children using methodological design features from the Dimensional Change Card Sort (DCCS) Task. This addition allowed the day/night task to serve as a better analogue to the Stroop task, which is an inhibitory control task commonly used with adults. In addition, electroencephalogram (EEG) illuminated the neural patterns of the task in children at age four. This study demonstrated that the borders condition of the day/night task is an appropriate executive function task that can be used with preschool aged children. / Master of Science

Overweight and obesity are prevalent public health problems that impact physical, mental, and social health. Many studies have evaluated weight loss treatments, but most individuals are unsuccessful at maintaining weight loss long-term. Behavioral and cognitive interventions may be effective in promoting weight loss and weight loss maintenance. One cognitive intervention that has shown potential success in reducing weight and caloric intake is inhibitory control training (ICT). ICT involves trainings where individuals are asked to repeatedly withhold dominant responses to unhealthy or high-calorie food images in an effort to increase food-related inhibitory control abilities. Reductions in caloric intake or weight may occur after as little as one week of ICT; however, it is unclear how more frequent ICT sessions promote weight loss and reduce caloric intake. Further, studies on food-specific ICT are generally poorly powered and it is unclear how ICT affects underlying cognitive and neural mechanisms. One way to measure inhibitory control processes is through the N2 component of the scalp-recorded event-related potential (ERP). The amplitude of the N2 ERP component tends to be larger (i.e., more negative) when an individual inhibits a dominant response during go/no-go tasks compared to non-inhibition go trials. I conducted a quasi-randomized controlled trial where 100 individuals with overweight or obesity were assigned to either a generic (active control; n = 48) or food-specific ICT (experimental group; n = 52). ICTs were completed four times per week for four weeks. Weight and caloric intake were obtained at baseline, immediately after four-weeks of ICT, and at a 12-week follow-up. Participants also completed a high-calorie and a neutral go/no-go task while electroencephalogram (EEG) was recorded at each visit. Results from mixed model analyses suggest that neither weight, caloric intake, nor N2 ERP component amplitude towards high-calorie foods changed at post-testing or at the 12-week follow up for either group. Regression analyses suggest that individuals with lower baseline levels of inhibition may show greater weight loss and reductions in caloric intake after a generic ICT, while individuals with higher baseline levels of inhibition may show greater weight loss and reductions in caloric intake after a food-specific ICT. Self-report ratings indicated the appetitive drive towards food decreased over the course of the study, particularly for individuals with higher levels of baseline inhibition. Overall, generic- or food-specific ICT did not affect weight, caloric intake, or food-specific N2 ERP amplitude. Food-specific ICT may be more effective in reducing caloric intake and weight for individuals with larger inhibition responses to food stimuli, while generic ICT may be more effective in reducing caloric intake and weight for individuals with smaller inhibition responses to food stimuli. ICT may also be targeting other mediating processes, such as the appetitive value of food, as opposed to improving food-specific inhibitory control.

Eating unhealthy foods and eating past satiety are inappropriate behaviors that promote obesity. The ability to effectively inhibit an inappropriate behavior is a key component of cognitive restraint and its impairment has been previously linked to obesity. In this study, a Go/No-Go fMRI task was completed by a cohort of adult women that had experienced initial weight loss followed by various levels of weight regain or continued weight loss. Region of interest fMRI analysis revealed that greater total weight loss was significantly related to decreasing activation in the right inferior frontal gyrus and the right superior frontal gyrus. These results suggest that as weight loss increases fewer cognitive resources are needed in order to maintain levels of inhibitory control. This cognitive efficiency, though only partially supported by better task performance, is supported by greater exercise. An analysis of resting state patterns of correlation between task-activated regions revealed a significant correlation between the right inferior frontal gyrus and the left middle temporal gyrus. The strength of this relationship was significantly correlated with increasing total weight loss and continued weight loss over time. Cognitive restraint was also associated with this fronto-temporal correlation and provides support for cognitive efficiency. Right inferior frontal gyrus was also correlated with left inferior frontal gyrus and this relationship was positively correlated with initial weight loss suggesting that fewer neurocognitive resources were required by those who were able to achieve greater initial weight loss.

Negative life stress and maternal inhibitory control are both critical ingredients involved in the shaping and maintaining of the quality of parenting behaviors. This study explored both how the experience of stressful life events and inhibitory control relate to two particular types of parenting behaviors: harsh/controlling and autonomy-supportive. Given that these two types of parenting have broad implications for children’s developmental trajectories, it is important to further enhance our understanding of the etiological factors that both shape and maintain parenting practices. Utilizing a high-risk sample (i.e. low SES, high presence of documented child maltreatment) of mothers with pre-school aged children, this study did not support the relationship between the experience of stressful life events, maternal inhibitory control and quality of parenting. However, post hoc analyses of life stress using a measure of objective SES did yield a significant link between stress and the presence of autonomy-supportive parenting. This study expands the current understanding of how stress and inhibitory control relate to parenting behaviors. Implications of this study for practice and research are discussed.

<p>Deficits in higher order cognitive processes such as inhibitory control and working memory (WM), grouped under the term of executive function (EF), have been shown to constitute one important component of the complex neuropsychology of Attention Deficit Hyperactivity Disorder (ADHD). The aim of the present thesis was to examine EF in relation to ADHD, with primary focus on structure (i.e., dimensions) and developmental change. Rooted in the developmental and dimensional perspectives of ADHD, which propose that the disorder represents the extreme of or quantitative delays in traits that are present throughout the general population, four studies (I-IV) based on non-clinical and clinical samples of children at different developmental levels were conducted.</p><p>Together, the results from Study I-IV suggest that inhibitory control and WM are important components of EF in typically developing children as well as in relation to ADHD symptoms. Of particular interest are the findings from Study II, III, and IV, showing that inhibitory control and WM seem to be of different importance depending on the child’s age. More specifically, the non-clinical and clinical studies suggest that inhibitory control and WM are important in predicting ADHD symptoms, with deficits in inhibitory control primarily being associated with ADHD symptoms for preschool and younger elementary school-aged children, whereas deficits in WM are associated with ADHD symptoms for older elementary school-aged children. </p><p>In conclusion, the results of the present thesis are consistent with Barkley’s (1997) developmental prediction concerning the relation between EF and ADHD, which suggests that impaired inhibitory control is an early developmental precursor to or a factor that “sets the stage” for deficits in more complex EFs such as WM. The home taking message from the present thesis is that age matters not only in the behavioral, but also in the neuropsychological manifestation of ADHD. To our knowledge, these findings are among the first to show that age is an important factor that should be taken into account in future ADHD research, theory, and treatment.</p>

Deficits in higher order cognitive processes such as inhibitory control and working memory (WM), grouped under the term of executive function (EF), have been shown to constitute one important component of the complex neuropsychology of Attention Deficit Hyperactivity Disorder (ADHD). The aim of the present thesis was to examine EF in relation to ADHD, with primary focus on structure (i.e., dimensions) and developmental change. Rooted in the developmental and dimensional perspectives of ADHD, which propose that the disorder represents the extreme of or quantitative delays in traits that are present throughout the general population, four studies (I-IV) based on non-clinical and clinical samples of children at different developmental levels were conducted. Together, the results from Study I-IV suggest that inhibitory control and WM are important components of EF in typically developing children as well as in relation to ADHD symptoms. Of particular interest are the findings from Study II, III, and IV, showing that inhibitory control and WM seem to be of different importance depending on the child’s age. More specifically, the non-clinical and clinical studies suggest that inhibitory control and WM are important in predicting ADHD symptoms, with deficits in inhibitory control primarily being associated with ADHD symptoms for preschool and younger elementary school-aged children, whereas deficits in WM are associated with ADHD symptoms for older elementary school-aged children. In conclusion, the results of the present thesis are consistent with Barkley’s (1997) developmental prediction concerning the relation between EF and ADHD, which suggests that impaired inhibitory control is an early developmental precursor to or a factor that “sets the stage” for deficits in more complex EFs such as WM. The home taking message from the present thesis is that age matters not only in the behavioral, but also in the neuropsychological manifestation of ADHD. To our knowledge, these findings are among the first to show that age is an important factor that should be taken into account in future ADHD research, theory, and treatment.

The current study investigates whether younger adults process distraction semantically and how age influences the level of distraction processing. In a first experiment, younger adults’ processing of distraction was examined by comparing implicit and explicit memory for that distraction. Then, in a second experiment, younger and older adults’ semantic processing of distractors was directly tested by examining memory for distractors on a conceptually based category-generation task. Younger adults showed equivalent implicit and explicit distractor memory in the first experiment and no conceptual priming for distractors on the category-generation task of the second experiment. Older adults, on the other hand, showed reliable conceptual priming for distractors, and the effect was significantly correlated with age in that group. The results collectively suggest that older, but not younger, adults engage in elaborate processing of irrelevant information, and that this effect is possibly tied to inhibitory control abilities that tend to decrease with age.

Children use many cues to differentiate reality from fantasy, including context, testimony from others, and physical evidence in the world around them. However, due to individual differences, some children hold strong reality status biases that interfere with their ability to infer reality status from these cues correctly. This research identified two general cognitive skills, inhibitory control and a metacognitive understanding of certainty, which serve as mechanisms for overcoming biases to infer reality status. In general, children with a high interest in fantastical play and older children with poorer developed inhibitory control skills are more likely to display a reality status bias. Additionally, children with reality status biases are more likely to overcome them to infer reality status correctly when they have a better metacognitive understanding of certainty and better developed inhibitory control. This research informs both the fantasy/reality literature and the scientific reasoning literature in demonstrating how biases can affect children's judgments. / text

The primary aim of this dissertation is to address an important issue of individual susceptibility to false memories. Specifically, what is the role inhibitory control (IC) in children’s and adult’s propensity to producing false memories? Inhibitory control within the context of the current study is defined on the basis of performance on selective attention tasks. Inhibitory control is discussed within this dissertation as it is reflected in two selective attention tasks, Stroop and Negative Priming. While the false memory effect, as reflected in the Deese/Roediger and McDermott paradigm (Roediger & McDermott, 1995), is one of the most widely studied memory phenomenon, the current study is important as it provides some insights into the relation between attention and memory. An interesting finding in the DRM false memory effect is that participants often report having a clear false memory of having seen or heard the non-presented critical lure item (CL item). Such memory illusions have been informative on how memory works. The current study adds to this body of research by providing converging evidence of how individual differences in the sensitivity to the false memory effect may occur, and how this sensitivity may reflect the same IC mechanisms involved in selective attention tasks. The basic notion examined within this dissertation is that when recognition memory is tested in the DRM paradigm, individuals have to select information that was studied and simultaneously inhibit highly activated yet non-presented information in memory, in order to correctly reject the CL item. If the notion that individual differences in sensitivity to the false memory effect is indeed related to a basic IC mechanism, then a relationship should be found between measures of IC in selective attention tasks and rates of false memories in the DRM test. The current study incorporates three experiments. Experiments 1 and 2 are broken down into parts ‘a’ and ‘b’, with each part varying in respect to the IC measure. In part a, participants were assigned to an inhibitory control group (IC group) on the basis of Stroop interference. In part b, participants are assigned to IC groups on the basis of a combined measure of inhibitory control that is, Stroop and Negative Priming. The third experiment assigned participants on the basis of a combined measure of IC, and then considered the relation between the duration of IC over a number of DRM word-lists presented simultaneously prior to the recognition test. Experiment 3 also compared the robust effect of IC on the propensity to produce false memories across all three experiments. The results of this study can be summarized as follows. In each experiment there was clear evidence of a relation between IC estimates and proportion of false memories. As predicted, individuals assigned to a Less IC group produced a higher proportion of false memories than those assigned to the More IC group. Inhibitory control differences did not modulate differences in correct or incorrect recognition in general (hits and false alarms to unrelated distractors). This second finding is important because it suggests a specific effect of IC in false memories, rather than a general breakdown in memory processes. The IC effect in false memories occurred in children (8-year olds and 10-year olds) as well as adults. Furthermore, the IC effect appeared to be additive with age; i.e., all groups produced a similar pattern across all three experiments. Last, the combined estimate of IC was found to be a more sensitive measure of false memories than a single index of IC; however, this was found in relation to adults but not for children. A number of additional manipulations and measures of interest were also included. Experiment 2 found clear evidence of an effect of IC on remember responses, not only were Less IC individuals more likely to produce false alarms to critical lure items, they were also more likely to distinctly respond they “remembered” the CL item as opposed to only “knowing” the CL had been presented. Examination of reaction times (RTs) to false alarms as a function of IC group found the Less IC group were faster to make false alarm responses to CL items, whereas the More IC group were slower to make false responses CL items. As predicted the relation between IC and the false memory effect was modulated by the random versus blocked presentation manipulation in Experiment 3. Specifically, decreased rates of false memories were found in the random presentation format compared to the blocked format. Interestingly however, a small effect of IC group in false memories was found even in the random condition. From this study it can be concluded that individual susceptibility to the false memory effect is in part modulated by inhibitory control. Individuals who demonstrate less effective IC show a greater propensity to false memories than those who demonstrate more effective IC. The IC effect of false memories was found to be robust, with converging evidence found across all three experiments. In relation to the development of inhibitory control, consistent with the research of Pritchard and Neumann (2004, 2009), and Lechuga and colleagues (2006), the results of this study suggest IC is fully developed in young children. However, their ability to accurately encode, retain and retrieve information would appear to develop at a different rate than IC. Specifically, it may be that while younger children are able to utilize IC in memory processes, they have yet to fully develop a richly interconnected semantic network. On the other hand, older children and adults would appear to have a more fully developed semantic network. This series of experiments presents a novel demonstration of the relation between inhibitory control and false memories. As such, this study has the potential to provide new insight into a cognitive mechanism that may be responsible for both developmental trends and for individual differences in the regulation of false memories. Moreover, if the mechanism responsible for mediating false memories is causally linked to performance on selective attention tasks in the systematic way that is proposed, it may be possible in the future to utilize IC measures to assist in identifying individuals who have an exaggerated propensity to form false memories, as well as those more prone to resist them.

There is growing evidence that acute changes in fundamental mechanisms of impulse control contribute to the transition from social drinking to abusive drinking. One component of impulsivity concerns the ability to inhibit maladaptive behaviors (i.e., inhibitory control). Inhibitory mechanisms are reliably shown to be sensitive to the impairing effects of alcohol, and studies have begun to show that this impairment fails to recover at the same speed as other aspects of behavior. However, the degree to which inhibitory control develops tolerance to alcohol has only been examined under limited conditions. This dissertation consists of three studies examining contexts in which tolerance has been observed for a host of prototypic behaviors, and will compare the degree to which it fails to develop for inhibitory control. Study 1 examined the rate of recovery for inhibitory control compared with other behaviors as blood alcohol concentrations (BACs) declined to zero following a dose of alcohol in 24 social drinkers. Results revealed prolonged alcohol impairment of inhibitory control along the BAC curve, even as BACs approached zero. By contrast, behaviors including reaction time and motor coordination began to show recovery markedly faster, as BACs were still significantly elevated. Study 2 examined the degree to which recent drinking patterns predict acute alcohol impairment from alcohol in a group of 52 drinkers. Recent, heavy consumption predicted less impairment of motor coordination, but bore no relationship to the magnitude of impairment of inhibitory control. Study 3 examined whether increasing the stimulus strength of environmental cues signaling the need to inhibit behavior could reduce alcohol impairment of inhibitory control in 56 participants. Results showed that increasing stimuli strength reduced alcohol impairment of behavioral activation, but actually increased inhibitory failures. Taken together, the findings contribute to the growing body of evidence suggesting that inhibitory control is especially vulnerable to the impairing effects of alcohol compared with other behaviors. Indeed, these studies systematically assessed the pharmacokinetic and environmental factors that contribute to tolerance, indicating that inhibition is disrupted in circumstances under which response activation is unimpaired. The findings have important implications for understanding the behaviorally-disruptive effects of alcohol.