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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.

Studies were conducted to investigate relationships between trait emotion regulation variables (including reappraisal and suppression) and selective attention to negative emotional information. Correlation analyses of data in experiment 1 showed that trait-suppression was related to early attentional avoidance of angry faces, while reappraisal showed no relationship to attention. Experiment 2 directly compared selective attention to angry faces in groups of high trait-suppressors and high trait-reappraisers. Since reappraisers are also low trait-anxious and suppressors are high trait-anxious, low emotion regulating high- and low-anxious control groups were included. Contrary to findings from experiment 1, trait-suppressors did not have lower selective attention to angry faces than low-regulating high anxious controls. Trait-reappraisers in experiment 2 showed pronounced vigilance for angry faces compared to both trait suppressors and low-regulating low anxious controls. These results suggest that trait-suppression may reduce attentional threat biases. Conversely, trait-reappraisal combined with low anxiety may allow individuals to prioritize threat in attention.

Cognitive-behavioural based models of chronic pain contend that appraisals of harm affect the individual�s response to pain. It has been suggested that fear of pain and/or anxiety sensitivity predispose individuals to chronicity. However, other factors such as pain self-efficacy are believed to mediate between experience of pain and disability. According to this view, pain is maintained through hypervigilance towards painful sensations and subsequent avoidance. Four studies were conducted in order to evaluate the structure of fear-avoidance models of chronic pain, and also, to examine the role of hypervigilance as an underlying mechanism in maintenance of pain. In study one, using a sample of 207 consecutive patients, two models were tested. First, fear of movement model as proposed by Vlaeyen et al. (1995a) was examined. It was found that negative affectivity has direct effects on the fear and avoidance of pain, which in turn, contributes to disability. In total, fear/avoidance accounted for a significant amount of the variance of disability. In addition, severity of pain was found to increase pain disability, while itself is influenced still by negative affectivity. These findings supported the model of fear of pain as described by Vlaeyen et al. (1995a). Further, we found that self-efficacy may mediate the impact of fear of pain on disability and reduces the perceived physical disability. At the same time, self-efficacy was shown to have direct reductive impact on disability. However, both studies indicated that people who are fearful in response to pain are more likely to develop disability, although self-efficacy may play a moderating role. In the studies one, two, and three, the role of hypervigilance in over attending to pain was investigated. In study one a large sample of 168 chronic pain patients were studied. Questionnaires measuring different aspects of pain and a computerised version of the Dot-Probe Task were administered. Four types of words related to different dimensions of pain and matched neutral words were used as stimuli. Reaction times in response to the stimuli were recorded. A factorial design 3x4x2x2 and ANOVAs were employed to analyse the data. Chronic pain patients showed a cognitive bias to sensory pain words relative to affective, disability, and threat-related words. However, contrary to expectations, those high in fear of pain responded more slowly to stimuli than those less fearful of pain. These results suggest that patients with chronic pain problems selectively attend to sensory aspects of pain. However, selective attention appears to depend upon the nature of pain stimuli. For those who are highly fearful of pain they may not only selectively attend to pain-related information but also have difficulty disengaging from those stimuli. In study two, 35 chronic pain patients were compared with the same number matched healthy subjects. Both groups completed measures of fear of pain, anxiety sensitivity, depression and anxiety, in addition to dot probe task. Results indicated that both groups show similar attentional bias to sensory words in comparison with other word types. However, the level of this biasness was higher for chronic pain patients. Lack of significant differences between patients and controls is discussed in the context of possible evolutionary value of sensitivity to pain as an adaptive reaction in healthy controls, and contrary, as a maladaptive response to pain in chronic pain patients. The results of the previous research suggest that chronic pain patients demonstrate cognitive biases towards pain-related information and that such biases predict patient functioning. The forth study examined the degree to which a successful cognitive-behavioural program was able to modify the observed attentional bias towards sensory pain words. Forty-two patients with chronic pain conditions for more than three months were recruited prior to commencing a cognitive-behavioural pain management program. Participants were assessed before the program, after the program and at one-month follow-up. Results confirmed that chronic pain patients exhibited biased attention towards sensory pain-related words at pre-treatment. These biases were still evident at post-treatment, but were no longer statistically significant at follow up. Multiple regression analyses indicated that the changes in attentional bias towards sensory words between post-treatment and follow-up were predicted by pre- to post- treatment changes in fear of movement (Tampa Scale for Kinesiophobia) but not other relevant variables, such as fear of pain or anxiety sensitivity. These results demonstrate that successful cognitive-behavioural treatments can reduce selective attention, thought to be indicative of hypervigilance towards pain. Moreover, these biases appear to be changed by reducing the fear associated with movement. Theoretically, these results provide support for the fear of (re)injury model of pain. Clinically, this study supports the contention that fear of (re)injury and movement is an appropriate target of pain management and that reducing these fears causes patients to attend less to pain-related stimuli.

Many complex decisions require integrating and assessing multiple streams of dynamic information whilst determining how to act. This dynamic information often contains rhythmic structures which our sensory systems can adapt to and use to anticipate future events. Despite the close relationship between rhythmic temporal expectations and complex decision making being self evident, no experiments explicitly attempt to understand this interdependence. If the theories that have emerged from both domains are to generalise to complex interactive behaviour, the effects of dynamic context on complex decisions must be considered. I argue that timing research must move beyond simple decisions and develop a new experimental framework for addressing the problem. This includes increasing the complexity of experimental tasks, testing the effects of timing on perceptual averaging and subjective value decisions, incorporating timing as an inherent dimension of targets, testing degrees of aperiodicity and exploring the effects that prior knowledge about the temporal structure of a stimulus has on choice. Seven behavioural experiments are reported that implement the new experimental framework. Five use a complex auditory-spatial averaging task to examine effects of periodicity, expectation, prior knowledge and related parameters such as IOI variance. One tests the effects of rhythmic variability and stimulus duration on auditory detection to determine specificity to complex decision making, and one investigates the effects of timing on audio-visual subjective value decisions. The results show that existing theories of temporal expectation do not necessarily generalise to complex decision making. Periodicity reduces the amount of information that is needed to form complex decisions. However, the effects of periodicity (or degree of aperiodicity) on choice are dependent on a number of factors associated with prior knowledge, stimulus rate, variance, decision type and task complexity. Using these findings I develop an explanatory framework called "dynamic inhibition and boosting" that better accounts for behavioural data in the literature compared with existing theories. This explanation is supported by the novel proposal that temporal expectations influence confidence and perceived risk.

Foi estudado o efeito de priming negativo associado à supressão do distrator palavra-cor de Stroop (Estudo 1), à supressão do local (Estudo 2) e à identidade do distrator (Estudos 3 e 4). No Estudo 1 constatou-se que a prática prévia em palavras-cor eliminou o efeito da ordem das condições experimentais sobre o índice de priming negativo. No Estudo 2, o efeito de priming negativo foi observado somente no hemicampo direito. A execução concorrente de uma tarefa verbal eliminou os efeitos de lateralidade, mas o efeito de priming negativo permaneceu significante. Estes achados são discutidos em termos de processamento interhemisférico sob condições que exigiriam maior controle da atenção. Os estudos 3 e 4 apresentam tarefas de comparação de pares de dígitos. A versão de papel e lápis da tarefa de comparação de dígitos permitiu avaliar de maneira simples e rápida o efeito de priming negativo. A versão computadorizada, revelou uma interação entre os componentes espacial e de identidade. Ambos os grupos de adultos jovens e idosos revelaram priming negativo nas tarefas de Stroop e de localização espacial. Nas tarefas de identificação do alvo somente os adultos jovens mostraram efeito de priming negativo. Os presentes achados são consistentes com a proposta de mecanismos inibitórios diferenciados na supressão da identidade e de localização espacial. / The development of sensitive and simple tests for the assessment of the negative priming effect has theoretical relevance to the elucidation of selective attention models, and also practical and potential clinical implications. The negative priming effect has been regarded as an index of inhibitory attentional processing and was proposed for the detection of syndromes that involve cognitive impairment. Diminished negative priming was reported in studies of individual differences, developmental stage, and clinical populations. However, evidences suggest that tasks requiring responses to the color feature, location or object identity of the stimuli may comprise distinct types of negative priming tasks. The following studies presents data for computerized and paper-and-pencil tasks to examine negative priming for Stroop color-word, location and identity distractors. All four studies take into account aging effects across the tasks. For comparisons between age-groups, proportional performance scores (ratio) were used. A first study employed a reading-sheet Stroop-color-word task, in which the participant is asked to name the colors of the ink in which words with incongruent color names have been printed. Color-word interference is indicated by increased time to complete the conflicting color-word condition compared with a nonconflicting condition with patches of color or strings of Xs. The greater strength of the interference, when the target ink-color of the present stimulus is the distracting color name of the previous stimulus, is attributed to the negative priming effect. A pilot experiment showed that the order of the list conditions containing unrelated and related stimuli affected the negative priming index. The analysis of data demonstrated that a practice trial in color naming of conflicting color-words before the color-word conditions eliminated the effect of the order of the lists. In addition, there was a reliable Stroop reverse interference after practice in color naming, as indicated by the fact that the incongruent color-ink affected post-test word-reading, whereas it had no effect in the pretest word-reading. With practice procedure, older and younger subjects did not differ in their proportional interference scores, whereas the negative priming and reverse effects were increased for older adults. Study 2 examined the negative-priming effect in a spatial localization task under single- and dual-task conditions. The task required the subject to detect the location of a target letter, ‘O’, while ignoring a distractor letter, ‘X’, when it was present. Significant negative-priming effects were observed under both task conditions, with increased response times for trials in which target location had matched the location of the distractor on the preceding. The magnitude of the negative priming effect was not different for older and younger adults. The performance in the single-task condition showed laterality effects with a right visual field advantage for control and target-alone trials, but not for related trials. In consequence, in the single-task condition, negative priming was observed only for targets displayed in the right hemifield. However, a concurrent digit span task, with a load level that had shown no affect on the dual-task coordination capacity, eliminated the laterality effects, but the negative priming effect remained. These results are considered as neuropsychological evidence that interhemispheric processes may operate under more controlled conditions. Studies 3 and 4 examined negative priming by using an identity-based task that required participants to select the greater of two-digits display or the digit that was paired with an asterisk. Study 3 presents data for a computerized version of the task. Negative-priming was expressed as a slowing in the time to name the digit that had been ignored in the preceding trial, compared to control trials with consecutive targets and distractors always different. Analysis of data revealed that negative priming was reliable only for younger adults, and only when target probe and distractor prime appeared at the same location, suggesting that suppression for location of distractor was underpinning the negative priming effect. However, response latencies for the control trials were facilitated when the target probe and the distractor prime shared the same location. Thus, local suppression affected negative priming for attended distractors with a cost in the response latency for ignored-repetition trials and with a gain in response latency for control trials when the locus of target-probe and distractor-prime was the same. In contrast, older adults’ performance showed local suppression for both ignored-repetition and control trials. This may explain the lack of negative priming for older adults in the digit-comparison task. Study 4 presents data for a new paper-and-pencil version of the digit-comparison task to obtain a practical measure of negative priming that do not require cumbersome technical equipment. In that task, subjects were asked to circle digits that were paired with asterisks and the greater of two digits in a series of digit pairs listed on a sheet of paper. For younger participants, but not for older participants, the time to complete the sheet with related pairs was slower than for unrelated pairs. In addition, the reduced scores of negative priming in older adults were associated with the lowest sustained attention scores from Toulouse-Piéron test. These results suggest that older adults’ performance in the digit-comparison task were mainly related to flexibility and sustained attentional scores, and the lower sustained attentional coefficient seemed to be the best predictor of diminished or reversed negative priming in older adults. Younger adults showed reliable negative priming across all tasks. In contrast, older adults showed negative priming in Stroop and spatial tasks, when compared with younger subjects performance, but reduced negative priming in identity suppression tasks. The findings are consistent with neurophysiological and behavioural evidence that identity and location suppressing may rely on separate inhibitory mechanisms, and that not all of these processes are weakened by factors associated with age.

This dissertation presents an investigation of the modifying role of attention and awareness in human learning and decision making. A series of experiments showed that performance in a range of tests of unconscious cognition can be better explained as resulting from conscious attention rather than from implicit processes. The first three experiments utilised a modification of the Serial Reaction Time task in order to measure the interaction of implicit and explicit learning processes. The results did not show evidence for an interaction, but did exhibit an effect of explicit knowledge of the underlying rules of the task. Subsequent studies examined the role of selective attention in learning. The investigation failed to provide evidence that learning inevitably results from the simple presentation of contingent stimuli over repeated trials. Instead, the learning effects appeared to be modulated by explicit attention to the association between stimuli. The following study with a novel test designed to measure the role of selective attention in prediction learning demonstrated that learning is not an obligatory consequence of simultaneous activation of representations of the associated stimuli. Rather, learning occurred only when attention was drawn explicitly to the association between the stimuli. Finally, the Deliberation without Attention Paradigm was tested in a replication study along with two novel versions of the task. Additional assessment of the conscious status of participants' judgments indicated that explicit deliberation and memory could best explain the effect and that the original test may not be a reliable measure of intuition. In summary, the data in these studies did not require explanation in terms of unconscious cognition. These results do not preclude the possibility that unconscious processes could occur in these or other designs. However, the present work emphasises the role conscious attention plays in human learning and decision making.

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This study investigated the effect of hearing six background noise conditions (silent baseline, pink noise, monologue, lively conversation, one-sided phone call, and cocktail noise) on acoustic measures of speech production during story retells in people with aphasia. Eleven individuals with aphasia and 11 age- and gender-matched control participants took part in the study. Participants heard the background noise conditions through open-back headphones while they retold six short stories. The examiner calculated mean and standard deviation of intensity, mean and standard deviation of fundamental frequency (F0), and speech rate in words per minute. A Matlab application that identified pauses (i.e., periods of silence greater than 200 ms) computed a speaking time ratio measure (i.e., time speaking versus time pausing). With the exception of the monologue and one-sided phone call condition, both people with aphasia and control participants significantly increase their intensity and F0 in the presence of background noise. Additionally, participants with aphasia have significantly lower speaking time ratios and speaking rates when compared to control participants. Participants make acoustic changes while hearing background noise; speech intensity rises in an effort to increase the signal-to-noise ratio, while mean F0 increases due to a presumed rise in subglottal pressure. Further research is suggested to investigate other acoustic differences, possibly at the segmental level, between speech produced in informational and energetic background noise.

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