Recent findings have suggested that the type of postural control seems to change, with certain conditions promoting a more conscious control and others, a more automatic control. It has been proposed that by withdrawing attention from postural control, external focus and cognitive task conditions allow automatic mechanisms to control sway more efficiently. The present dissertation aimed to investigate whether two types of postural control exist and to provide evidence for these two types of postural control in healthy young and older adults. In experiment 1, the effect of attentional focus and cognitive tasks was examined in healthy older adults. It was found that the cognitive task yielded improvements in stability compared to focus conditions, which highlighted the fact that automaticity is possible in this group. In experiment 2, the effect of attentional focus and cognitive tasks was once again observed in older adults, this time by including electromyographic recordings of lower leg muscles to examine if changes were due to stiffening. Although improvements were observed in external focus and cognitive task conditions compared to baseline and internal focus, no change occurred in muscle activity which lends further support to the idea that changes are due to automaticity. Finally, dynamic measures of sway were used to help interpret the changes that occurred in attentional focus and cognitive task conditions in both young and older adults. The wavelet transform revealed a change in sensory contributions to postural control in cognitive task conditions. There was a shift to increased contributions from the cerebellum and the vestibular system, and a decrease in visual contributions, compared to other conditions. Sample entropy revealed changes in complexity of sway, with cognitive tasks presenting more complex, irregular and efficient sway in both groups compared to baseline standing and attentional focus conditions. Finally, the rambling-trembling decomposition highlighted increases in the spinal reflex contributions to sway in external focus and difficult cognitive task conditions in young adults, while no change occurred in older adults. Results of these experiments provide the evidence of two types of postural control; a more automatic type in cognitive task conditions and a more conscious type in baseline and internal focus conditions. The external focus elicited some changes that could have indicated automaticity, but clear differences were still present between this condition and the cognitive tasks, which suggest automaticity of sway should be viewed as a continuum.

Postural control is the skill developed allowing body equilibrium and orientation, allowing for an efficient interaction with the environment. This skill is developed from birth; the first major landmark is the maintenance of an upright stance of a child, followed by the skill to walk freely (Shumway-Cook & Woollacott, 1985). A second important development occurs between the ages of 7-10 years-old when children start to demonstrate adult-like postural control (Riach & Hayes, 1987). While adults and older adults have shown increased automaticity in postural control in a dual-task (DT) (Potvin-Desrochers, Richer, & Lajoie, 2017), children have not yet been studied. The purpose of this experiment was to determine if children aged 6-7, 8-9, and 10-11 years old would demonstrate better postural stability, and greater postural automaticity in a DT condition than in a postural task (PT). To verify this, children were asked to stand still on a force platform in a PT or in a DT condition (PT with concurrent cognitive task). Results showed that older children had better postural stability, as demonstrated by a smaller sway area (7.20 cm2), reduced sway variability (0.60 cm), and a slower MV of sway (4.70 cm/s) than younger children (12.37 cm2, 0.78 cm, 6.60 cm/s). Older children also had a higher MPF in the PT (0.24 Hz) than in the DT (0.16 Hz). A wavelet transformation revealed a greater contribution of the ultra-low frequency band in the PT (49.9%) than in the DT (46.8%) across all children. These results demonstrated that older children were more stable than younger children. The smaller contribution to the ultra-low band in the DT may be an indication that children rely less heavily on their visual system in the DT. This research shows that children do not demonstrate automaticity of postural control between the ages of 6-11 years.

Individuals tend to underestimate situational causes and overly rely on trait causes in explaining negative behaviors of outgroup members, a tendency named the ultimate attribution error (Pettigrew, 1979). This attributional pattern is directly related to stereotyping, because attributing negative behaviors to internal, stable causes tends to perpetuate negative stereotypes of outgroup members. Recent research on implicit bias reduction revealed that circumventing individuals’ tendency to engage in the ultimate attribution error led to reduced stereotyping. More specifically, training White participants to consider situational factors in determining Blacks’ negative stereotypic behaviors led to decreased automatic stereotype activation. This technique was named Situational Attribution Training (Stewart, Latu, Kawakami, & Myers, 2010). In the current studies, I investigated the mechanisms and moderators of Situational Attribution Training. In Study 1, I investigated the effect of training on spontaneous situational inferences. Findings revealed that training did not increase spontaneous situational inferences: both training and control participants showed evidence of spontaneous situational inferences. In Study 2, I investigated whether correcting trait inferences by taking into account situational factors has become automatic after training. In addition, explicit prejudice, motivations to control prejudice, and cognitive complexity variables (need for cognition, personal need for structure) were investigated as moderators of training success. These findings revealed that Situational Attribution Training works best for individuals high in need for cognition, under conditions of no cognitive load, but not high cognitive load. Training increased implicit bias for individuals high in modern racism, regardless of their cognitive load. Possible explanations of these findings were discussed, including methodological limitations and theoretical implications.

Decades of priming research have revealed that environmental stimuli feed into our behaviours, often without any awareness of our using this information to guide our behaviour. This has been shown using plentiful stimuli across multiple contexts. One of the most socially rich stimuli in our environment is voice, and yet this has featured surprisingly little in behavioural research, particularly within social psychology. This thesis was written as a step towards addressing this gap, and it explores how voices might affect particular behaviours in different contexts. Three broad experiments, each with their own sub-experiments, investigated how voices, acting as proxies for social categories, could influence one's behaviour. In the first experiment, the responses to socially themed statements were influenced by the sex of the voice presenting those statements. Female voices primed more agreement to these statements than did male voices. In the second experiment, judgements of ambiguous stimuli and questions were also affected by voices, albeit in less clear ways. In the third experiment, the reaction times of participants were again affected by voices. Younger participants' reaction times were slower when listening to an older voice, and older participants' reaction times were faster when listening to an older voice. Across these three experiments, I found too that the presence of a voice led to task differences compared to when voice was absent. The combination of these experiments is, to my knowledge, the first to look at voice-based behavioural priming. How these results fit with selected existing theories, the potential to specify theories based on these results, and the possible practical applications of voice based priming are discussed.

Sequential movements have become a common experimental paradigm for evaluating the neural correlates of motor learning. Currently, the understanding is that motor sequence learning engages the cortico-cerebellar and cortico-striatal networks and that their contributions differ depending on the stage of learning. The prefrontal cortex (PFC), in particular, has been observed at the early/fast phase and late/slow phase of motor sequence learning, suggesting involvement in processes such as movement automaticity, stimulus-response conflicts, explicit learning, and retrieval, to name a few. However, it is difficult for neuroimaging studies to evaluate the relative permanence of motor sequence learning due to the financial burden associated with functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). In this dissertation, four experiments were performed to examine the functionality of functional near-infrared spectroscopy (fNIRS) in elucidating the role of the PFC in motor sequence learning and movement automaticity. The first experiment (Chapter 2) focused on validating fNIRS as a comparable technique to fMRI by replicating a previous motor sequence learning study (Wu et al., 2004) that reported decreased activity in the left dorsolateral prefrontal cortex (DLPFC) following achievement of movement automaticity. The fNIRS findings were unable to detect a similar decrease in the left DLPFC. The second experiment (Chapter 3) further investigated the cerebral oxygenation changes in the PFC following motor sequence learning. To enable better distinction between learning and performance, this experiment including multiple motor sequence tasks, a control group, four practice sessions and a retention phase. The findings revealed increased contributions from the right hemisphere (e.g., right ventrolateral PFC (VLPFC)) and the suggestion that the left DLPFC may not reflect movement automaticity but rather attentional investment in movement preparation. To address the signal processing concerns observed in experiment one and two, the third experiment (Chapter 4) investigated the effect of five motion correction techniques on the statistical outcomes of a motor sequence learning experiment. Additionally, the corrections were evaluated to determine which would yield the greatest improvement in hemodynamic response function (HRF) recovery and within-subject standard deviation. The findings revealed the location of significance to vary depending on the motion correction applied. Also, wavelet and spline + wavelet demonstrated limited improvement in reducing within-subject standard deviation. Lastly, the fourth experiment (Chapter 5) examined changes in the PFC associated with dual-task processing before and after motor sequence learning. Findings revealed decreased activity in the right DLPFC, medial PFC (mPFC), and orbitofrontal cortex following practice for dual-task sequence-4. A similar but marginal trend was observed in the right VLPFC. Minimal significance was observed during the dual-task sequence-12 task. Collectively, the findings of this dissertation suggest that 1) motor sequence learning when acquired with explicit knowledge requires contribution from predominately the right hemisphere, 2) the left DLPFC may represent attentional investment in movement preparation rather than movement automaticity, 3) the neural representations of dual-task processing are associated with the complexity of the motor sequence task, and 4) low-frequency motion artifacts may be difficult to remove using certain signal processing methods.

This dissertation investigated the acquisition and processing of anaphora by learners of English, using both "offline" methods such as paper-and-pencil written tests and "online" methods such as self-paced reading-for-comprehension. Three experiments were conducted. The first two experiments tested advanced Chinese ESL learners' knowledge and processing of anaphora. The focus of the first experiment was on whether participants automatically use gender and number cues, and verb information to interpret pronouns and reflexives during online processing. The second experiment manipulated gender and pragmatic cues to test whether participants have acquired knowledge of structural constraints on reflexive interpretation (i.e., the binding principles). The third experiment, using a pretest-treatment-posttest design, investigated the efficacy of computer-delivered Processing Instruction (PI) on the acquisition of structural constraints and the use of those constraints during reading. During the pretest, subjects completed a self-paced reading task and a written test. For the treatment, participants learned the grammatical constraints on reflexives through interaction with a computer program. Posttest assessment included one interpretation test, one sentence completion task, and one self-paced reading task. The role of feedback in Computer Assisted Language Learning was also examined. Results showed the following: (1) Advanced L2 learners were more sensitive to certain types of agreement information (gender) than others (number). (2) PI improved L2 learners' knowledge about constraints on reflexives as measured by offline tests. (3) PI led to improvement in learners' processing strategies as measured by online tasks. (4) No significant difference was found between the implicit feedback group and the explicit feedback group in the third experiment. Overall, this research highlights the importance of multiple types of assessment that tap the acquisition of grammatical knowledge as well as the proficiency with which learners use that knowledge during reading comprehension tasks.

Categorisation is the process by which items, behaviours and events are compartmentalised according to their defining attributes or properties. This may be based on simple perceptual similarities or on more complex conceptual webs. Whatever their selection criteria, categories expedite inferential capabilities, facilitating behavioural predictions and subsequently enabling response. Categorisation waives conscious effort whilst preserving that which is salient and as such, provides a highly efficient means of delineating and organising information within semantic memory. An ability to categorise is therefore fundamental to an individual’s capacity to understand the world and a necessary precursor to academic achievement. This thesis comprises a series of studies that were devised in order to investigate categorisational development in children. Study 1 involved the development of a theoretically and practically valid testing mechanism. A sample of 159 children, aged 30-50 months, participated in a series of investigations aimed at establishing the impact of test format and presentation dimensionality on categorisation performance. As a result of this, a new test battery was devised which enabled more fine grain differentiation than had been possible with the tests used by previous researchers. The battery measured four different aspects of preschool children’s categorisational abilities -categorising according to shape; according to colour; when presented with drawings of items, and when presented with the same items in the form of toys. Results found that children’s ability to categorise differed significantly according to their sex, socio-economic background and the dimensionality of the item. Study 2 utilised the same battery with 190 participants from demographically diverse cohorts. Significant differences were found between high and low socio-economic groups and between boys and girls. A Mixed- Factorial ANOVA, with a post-hoc Bonferroni demonstrated a main effect of sex; a main effect of cohort and an interaction between sex and cohort. A Kruskal-Wallis Test also showed age to be significant, confirming the findings of previous researchers concerning a developmental trajectory. However, it also found that relatively sophisticated conceptual webs emerge earlier than had previously been thought. Whilst the results from Study 2 had demonstrated relative homogeneity amongst socio-economic groups, it was noted that participants from the most disadvantaged neighbourhood performed better than those from the other low socio-economic cohort. As the two Nurseries employed different approaches, with one offering a formal curriculum and the other emphasising child-led play, it was decided that the final study would focus on categorical development in these two cohorts. The final study therefore investigated conceptual development during 96 participants’ first twelve weeks of nursery education. Forty-eight participants were drawn from a Community Nursery with a strong emphasis on child-led play and 48 were drawn from a Nursery attached to a Primary School, where the emphasis was on more formalised learning. Children’s categorisational abilities were measured during their first week in Nursery using the test battery devised for Study 1. They were then re-tested using a matched battery twelve weeks later. Change scores were calculated and analysed using a series of one-way ANOVAs. As anticipated, all participants made gains but the children who had participated in play made significantly greater gains in three out of the four measures. It is thus asserted that play is a key conducer in cognitive development and a causal executant in establishing rudimentary automaticity and, as such, should be the polestar of preschool education. This is particularly important for boys from low socio-economic backgrounds who face contiguous disadvantage. Therefore, this research demonstrates that memory-based research with young children should be conducted with toys and objects, rather than images, and that the link between social and educational stratification has its roots in early childhood and is best addressed through the provision of high-quality play opportunities.

La tâche Stroop est une tâche très utilisée en psychologie car elle permet entre autres l'étude des processus dit automatiques. Cependant, récemment l'utilisation d'une présentation bicolore dans cette tâche, associée aux études liées à une tâche de détection de lettre dans une tâche d'amorçage, suggère que l'accès à la sémantique ne serait pas automatique. Ce qui impliquerait une interprétation différente de la tâche Stroop. Nous avons testé l'hypothèse qu'en présentation bicolore, la diminution observée de l'effet Stroop ne serait pas dû à un blocage de la sémantique mais à une augmentation des capacités d'inhibition. Nous avons pour cela utilisé une condition "associée" qui consistait à présenter des mots associés à une couleur (par exemple "ciel" associé à bleu) afin d'étudier plus spécifiquement l'accès à la sémantique. Dans nos deux premières études reproduisant le protocole des précédentes avec un nombre de participants plus important, nous n'observons pas de diminution de l'effet Stroop associé. Nous avons ensuite utilisé les potentiels évoqués pour montrer la présence de la N400 en condition bicolore pour les mots de couleurs et associés à une couleur dans la tâche Stroop. Pour finir, après avoir testé la présence du biais attentionnel chez des patients alcoolo-dépendants avec une version française du "Alcohol Stroop Test", nous avons montré que des ressources attentionnelles étaient nécessaires pour observer une diminution de l'effet Stroop en présentation bicolore. L'ensemble de nos résultats suggère que la diminution de l'effet Stroop en présentation bicolore nécessite des ressources attentionnelles et que donc l'accès à la sémantique serait un processus automatique, mieux inhibé dans la présentation bicolore. La tâche Stroop utilisée en clinique refléterait donc bien un processus d'inhibition de processus automatiques. / The Stroop task is a well-used task in psychology, in particular because it allows the study of automatic process. Recently the use of a single letter coloring presentation in this task, associated with the studies related to a task of detection of letter, suggests that the access to semantics would not be automatic. This implies a different interpretation from the Stroop task. We tested the assumption that in single letter colored presentation, the reduction observed in the Stroop Effect would not be due to a blocking of semantics but to an increase on the capacities of inhibition. For that we used an "associated" condition where we presented words associated with a color (for example sky associated with blue) to more specifically study the access to semantics. In our two first studies reproducing the preceding protocol with a more important number of participants, we do not observe reduction in the associated stroop effect. Then we used the Potentials Evoked to show the presence of N400 in the single letter colored condition for color words and associated-words. To finish, after having tested the presence of an attentional bias among patients alcohol-dependent with a French version on Alcohol Stroop Test, we showed that attentional resources were necessary to observe a reduction in the Stroop Effect in single letter colored presentation. The whole of our results suggest that the reduction in the Stroop Effect in single letter colored presentation requires attentional resources. The semantic access would be an automatic process. The sense of the word could be inhibiting after activation in single letter colored presentation. The Stroop task used in clinical would thus reflect an inhibition capacity of automatic process.

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