Attention is one of the most impaired cognitive functions in schizophrenia; however, the precise mechanisms underlying schizophrenia-related attention impairment are unclear. Progress in identifying these mechanisms has been hampered by using methods that are not designed to isolate specific cognitive processes. The purpose of the present dissertation was to investigate visual attention among patients with schizophrenia using the visual search paradigm — the dominant paradigm for studying attention in the cognitive sciences. Moreover, the current study used eye-tracking methodology to more finely examine the mechanisms underlying impaired visual search in this clinical population. This dissertation had three main objectives: (1) to investigate whether patients with schizophrenia have smaller and/or less dynamic visual spans, (2) to examine whether certain mechanisms guiding the visual selection of objects are impaired in schizophrenia, and (3) to determine the contribution of visual search performance to substitution test performance. Results indicated that patients’ visual spans are both smaller and less dynamic compared to healthy controls. On the other hand, selectivity for more informative distractors is intact in schizophrenia; however, impaired motion perception results in impaired target discrimination in the context of intact target selection. Results also indicated that visual search performance is a primary determinant of substitution test performance. Collectively, these data demonstrate, on one hand, an impairment among patients with schizophrenia in the distribution and flexible modulation of visual attention and, on the other hand, intact visual selective attention in the presence of strong bottom-up cues. The current data also demonstrate the important contribution of visual attention to a highly sensitive neuropsychological test and, by inference, to patients’ cognitive and real-world functioning.

Attention is one of the most impaired cognitive functions in schizophrenia; however, the precise mechanisms underlying schizophrenia-related attention impairment are unclear. Progress in identifying these mechanisms has been hampered by using methods that are not designed to isolate specific cognitive processes. The purpose of the present dissertation was to investigate visual attention among patients with schizophrenia using the visual search paradigm — the dominant paradigm for studying attention in the cognitive sciences. Moreover, the current study used eye-tracking methodology to more finely examine the mechanisms underlying impaired visual search in this clinical population. This dissertation had three main objectives: (1) to investigate whether patients with schizophrenia have smaller and/or less dynamic visual spans, (2) to examine whether certain mechanisms guiding the visual selection of objects are impaired in schizophrenia, and (3) to determine the contribution of visual search performance to substitution test performance. Results indicated that patients’ visual spans are both smaller and less dynamic compared to healthy controls. On the other hand, selectivity for more informative distractors is intact in schizophrenia; however, impaired motion perception results in impaired target discrimination in the context of intact target selection. Results also indicated that visual search performance is a primary determinant of substitution test performance. Collectively, these data demonstrate, on one hand, an impairment among patients with schizophrenia in the distribution and flexible modulation of visual attention and, on the other hand, intact visual selective attention in the presence of strong bottom-up cues. The current data also demonstrate the important contribution of visual attention to a highly sensitive neuropsychological test and, by inference, to patients’ cognitive and real-world functioning.

Benford’s Law states that the first significant digit for most data is not uniformly distributed. Instead, it follows the distribution: P(d = d1) = log10(1 + 1/d1) for d1 ϵ {1, 2, …, 9}. In 2006, my supervisor, Dr. Mary Lesperance et. al tested the goodness-of-fit of data to Benford’s Law using the first significant digit. Here we extended the research to the first two significant digits by performing several statistical tests – LR-multinomial, LR-decreasing, LR-generalized Benford, LR-Rodriguez, Cramѐr-von Mises Wd2, Ud2, and Ad2 and Pearson’s χ2; and six simultaneous confidence intervals – Quesenberry, Goodman, Bailey Angular, Bailey Square, Fitzpatrick and Sison. When testing compliance with Benford’s Law, we found that the test statistics LR-generalized Benford, Wd2 and Ad2 performed well for Generalized Benford distribution, Uniform/Benford mixture distribution and Hill/Benford mixture distribution while Pearson’s χ2 and LR-multinomial statistics are more appropriate for the contaminated additive/multiplicative distribution. With respect to simultaneous confidence intervals, we recommend Goodman and Sison to detect deviation from Benford’s Law.

In 1972, professor Grigore Moisil, the most famous Romanian academician for Mathematics, said about Combinatorics, that it is “an opportunity of a renewed gladness”, because “each problem in the domain asks for its solving, an expenditure without any economy of the human intelligence”. More, the research methods, used in Combinatorics, are different from a problem to the other! This is the explanation for the existence of my actual paper, in which I propose to teach Combinatorics, using selected problems. MS classification: 05A05, 97D50.

In his keynote address to the National Council of Teachers of Mathematics research pre-session, Sloane (2006b) challenged mathematics education researchers to ‘quantify qualitative insights’. This quasi-experimental study used blended methods to investigate the development of two-digit addition and subtraction strategies. Concurrent classroom teaching experiments were conducted in two intact first grade classrooms (n = 41) in a mid-Atlantic American public school. From a pragmatic emergent perspective, design research (Gravemeijer & Cobb, 2006) was used to develop local instructional theory. An amplified theoretical framework for early base-ten strategies is explicated. Multilevel modelling for repeated measures was used to evaluate the differences in strategy usage between classes across occasions and the association of particular pedagogical practices with the emergence of incrementing and decrementing by ten (N10) or decomposition (1010) strategies (Beishuizen, Felix, & Beishuizen, 1990).The two matched classes were not different in terms of gender, poverty, race, pre-assessment performance, and special education services. After the first unit of instruction with differentiated pedagogical tools, the collection class was significantly (p = .001) more likely to use 1010 than the linear class. No difference was demonstrated during the post-assessment. Students in both classes were more likely to use N10 during the last structured interview than in the first (p < .0001). Furthermore, there was no difference between the two classes in using any advanced strategy; however, students in both classes were more likely to use an advanced strategy at the conclusion of the study than they were initially (p = .033). The order of emergence of 1010 and N10 was not associated with the ability to develop both strategies, but there was an association (p < .001) between use of an advanced strategy and success on a district-mandated written assessment of two-digit addition and subtraction.Two original instructional sequences of contextually-based investigations are presented. Protocols transcribed from videotaped lessons and dynamic assessment interviews are presented to illuminate specific constructs detected and to illustrate the pedagogical techniques. An amplified framework for early place value constructs is proposed. Recommendations for future studies, curricular changes, and the need of early intervention are discussed.

In his keynote address to the National Council of Teachers of Mathematics research pre-session, Sloane (2006b) challenged mathematics education researchers to ‘quantify qualitative insights’. This quasi-experimental study used blended methods to investigate the development of two-digit addition and subtraction strategies. Concurrent classroom teaching experiments were conducted in two intact first grade classrooms (n = 41) in a mid-Atlantic American public school. From a pragmatic emergent perspective, design research (Gravemeijer & Cobb, 2006) was used to develop local instructional theory. An amplified theoretical framework for early base-ten strategies is explicated. Multilevel modelling for repeated measures was used to evaluate the differences in strategy usage between classes across occasions and the association of particular pedagogical practices with the emergence of incrementing and decrementing by ten (N10) or decomposition (1010) strategies (Beishuizen, Felix, & Beishuizen, 1990).The two matched classes were not different in terms of gender, poverty, race, pre-assessment performance, and special education services. After the first unit of instruction with differentiated pedagogical tools, the collection class was significantly (p = .001) more likely to use 1010 than the linear class. No difference was demonstrated during the post-assessment. Students in both classes were more likely to use N10 during the last structured interview than in the first (p < .0001). Furthermore, there was no difference between the two classes in using any advanced strategy; however, students in both classes were more likely to use an advanced strategy at the conclusion of the study than they were initially (p = .033). The order of emergence of 1010 and N10 was not associated with the ability to develop both strategies, but there was an association (p < .001) between use of an advanced strategy and success on a district-mandated written assessment of two-digit addition and subtraction.Two original instructional sequences of contextually-based investigations are presented. Protocols transcribed from videotaped lessons and dynamic assessment interviews are presented to illuminate specific constructs detected and to illustrate the pedagogical techniques. An amplified framework for early place value constructs is proposed. Recommendations for future studies, curricular changes, and the need of early intervention are discussed.

The purpose of this experimental study was to investigate mindfulness strategies and their influence on working memory. The potential role of music in facilitating mindfulness practice is explored. Various listening exercises were investigated along with their influence on working memory (i.e. attention control). Thirty-four individuals were randomly assigned to participate in one of four listening groups: 1) mindfulness with music, 2) mindfulness without music, 3) music only, and 4) silence. Thirty-four participants engaged in a computerized digit-span task before and after the listening exercise to assess pre- and post-test working memory performance. Thirty participants were included in data-analysis due to technical errors in data collection. Differences between listening exercises were explored and comparisons were made between mindfulness, non-mindfulness, music, and non-music based exercises. Two-tailed independent samples t-tests found no significant differences in working memory when comparing mindfulness versus non-mindfulness and music versus non-music based exercises. An Analysis of Variance (ANOVA) indicated no significant differences in working memory for any of the listening conditions. Results call for further examination of control variables and methodology to explore the role of music listening in mindfulness practice. Implications for further research and contributions to music therapy and music education are considered.

In 1972, professor Grigore Moisil, the most famous Romanian academician for Mathematics, said about Combinatorics, that it is “an opportunity of a renewed gladness”, because “each problem in the domain asks for its solving, an expenditure without any economy of the human intelligence”. More, the research methods, used in Combinatorics, are different from a problem to the other! This is the explanation for the existence of my actual paper, in which I propose to teach Combinatorics, using selected problems. MS classification: 05A05, 97D50.

No description available.

Cette thèse porte sur l’évaluation de l’impact de certains composés environnementaux sur la fécondité féminine, tel que mesuré par le délai de conception (« time to pregnancy » en anglais, ou TTP). Cette recherche a été réalisée dans le cadre de l’Étude mère-enfant sur les composés chimiques de l’environnement (MIREC), une cohorte de grossesse de 2001 femmes recrutées durant le premier trimestre dans dix villes canadiennes de 2008 à 2011. Les données des questionnaires et les échantillons biologiques ont servi à évaluer l’effet de deux groupes de composés : les persistants [composés perfluorés – perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA) et perfluorohexane sulfonate (PFHxS)] et les non persistants (bisphénol A, triclosan et phtalates). Cette thèse comprend également une analyse du potentiel du ratio index-annulaire (2D:4D) comme mesure de sensibilité endocrinienne. À ce jour, des mesures anthropométriques ont été collectées sur environ 800 mères-enfants dans le cadre de l’Étude mère-enfant sur les composés chimiques de l’environnement : biomonitoring et neurodéveloppement à la petite enfance (MIREC CD Plus), un suivi de la cohorte MIREC portant sur la croissance et le développement des enfants jusqu’à 5 ans. Sur l’ensemble, les résultats de cette thèse permettent d’étoffer les preuves concernant les effets adverses potentiels de plusieurs contaminants environnementaux sur la fécondité féminine, telle que mesurée par le TTP. Dans le premier article, nous avons montré une association entre les PFOA et les PFHxS et une baisse de fécondité, ce que d’autres recherches avaient déjà révélé. Dans le deuxième article, nous avons évalué l’effet du triclosan sur le TTP, ce qui n’avait jamais été examiné, pour montrer un délai plus élevé chez les femmes du quartile supérieur d’exposition. De plus, nos résultats sont en accord avec ceux de la seule étude ayant évalué l’effet du Bisphénol A sur la fécondité féminine, qui n’avait pas détecté d’effet. Finalement, nos données semblent indiquer une association entre l’exposition des femmes aux phtalates et un TTP plus court, mais ces résultats ne sont pas statistiquement significatifs. En ce qui a trait au potentiel du ratio index-annuaire (2D:4D) pour mesurer la sensibilité endocrinienne chez les femmes, nos données ne permettent pas d’établir une association entre ce ratio et le TTP. Pour ce qui est des enfants, nous n’avons pas trouvé d’effet adverse entre le tabagisme de la mère durant la grossesse et leur ratio 2D:4D. Par conséquent, nos données ne semblent pas justifier l’utilisation du ratio 2D:4D pour mesurer la sensibilité endocrinienne en lien avec le potentiel reproducteur (basé sur le TTP) ou l’exposition des enfants au tabac durant le premier trimestre de grossesse. / In this thesis, we aimed to evaluate the impact of selected environmental compounds on female fecundity as measured by time to pregnancy (TTP). This research was conducted in the framework of the Maternal-Infant Research on Environmental Chemicals (MIREC) study, a pregnancy cohort of 2001 women recruited during the first trimester of pregnancy in ten cities across Canada between 2008 and 2011. Questionnaire data and biological samples were analyzed to assess the effect of two groups of compounds: persistent [perfluorinated compounds - perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorohexane sulfonate (PFHxS)-] and nonpersistent chemicals (Bisphenol A, Triclosan, and phthalates). In addition, this thesis aimed to examine the potential of the second to fourth finger digit ratio (2D:4D) as a sensitive-endocrine endpoint. To this end, anthropometric measurements were obtained in about 800 children and their mothers during the Early Childhood Biomonitoring and Neurodevelopment Study (MIREC-CD Plus), a MIREC follow-up conducted to measure growth and development up to age five. Overall, the results of this thesis have contributed to the evidence regarding the potential adverse effect of several environmental contaminants (ECs) on female fecundity as measured by TTP. In the first article, we found that PFOA and PFHxS were associated with diminished fecundity, supporting previous evidence that suggested a similar effect. In the second article, we assessed for the first time the effect of Triclosan on TTP, presenting evidence of delayed fecundity at the highest quartile of exposure. In addition, our findings agreed with those of the only study that has assessed the effect of Bisphenol A on female fecundity, and which showed no effect. Finally, we found some indication that female exposure to phthalates might be associated with a shorter TTP, although this finding did not reach statistical significance. With regard to the potential of the digit length ratio (2D:4D) as an endocrine-sensitive endpoint in women, our data do not support a strong association between 2D:4D and TTP. In children, we did not find an adverse impact of maternal smoking during pregnancy on children’s 2D:4D. Thus, our data do not support evidence to suggest that 2D:4D could be used as a potential reproductive endocrine-sensitive endpoint in women as measured by TTP, and in their offspring as measured by exposure to maternal smoking during the first trimester of pregnancy.