Fixed-width output analysis for Markov chain Monte Carlo

Markov chain Monte Carlo is a method of producing a correlated sample in order to estimate features of a target distribution via ergodic averages. A fundamental question is when should sampling stop? That is, when are the ergodic averages good estimates of the desired quantities? We consider a method that stops the simulation when the width of a confidence interval based on an ergodic average is less than a user-specified value. Hence calculating a Monte Carlo standard error is a critical step in assessing the simulation output. We consider the regenerative simulation and batch means methods of estimating the variance of the asymptotic normal distribution. We give sufficient conditions for the strong consistency of both methods and investigate their finite sample properties in a variety of examples

An exploration of the tensions experienced by bisexual men in long-term, monogamous, mixed-orientation relationships, whose bisexuality is known to their partners: Implications for counselling

This research explores the tensions encountered by bisexual men who are in a long-term monogamous relationship with someone who does not identify as bisexual, in the circumstance of their bisexuality being known to their partner. It was anticipated that tensions and partner anxieties would arise from preconceptions of bisexual men, as described in the literature. Semi-structured interviews were conducted with six bisexual men. The interview transcripts were analysed using Interpretative Phenomenological Analysis. The analysis uncovered three main themes: formative experiences; fear and longing; and the relationship. Within these themes, the participants revealed how formative experiences have left them aware that a part of them which they experience as fundamental may be met with rejection, stigma, denial, incomprehension, and misconceptions. The second theme revealed how the tension between the desire to be known and live authentically on the one hand, and the desire to be safe from rejection and stigma on the other, creates situations of living with partial disclosure, vigilance and caution, and inauthenticity. In the third theme, romantic relationships were shown to bring opportunities for being known and accepted; the possibility of rejection; further restrictions to living authentically; and the onus of answering to partner anxieties. Additionally, an incongruence was observed between participants’ averred feelings about their relationships and implicit feelings about the terms of their acceptance. The implications of the findings for counselling are considered from a person-centred perspective

The relationship between personality characteristics and Expressed Emotion in significant relationships

The relationship between Expressed Emotion (EE) and relapse and clinical outcomes in individuals with mental and physical health difficulties is well established. This thesis explores the relationship between EE and individual psychological factors. Part One is a systematic review of the psychological factors associated with different EE domains in caregivers of individuals with First Episode Psychosis. Fourteen studies met inclusion criteria. The review found that EE-Criticism and emotional over-involvement (EOI) have mutual as well as distinct psychological correlates in caregivers of individuals with a first episode of psychosis, and that these may differ from the correlates of EE found amongst caregivers of individuals with chronic psychosis. Part Two is an online study investigating personality characteristics that are associated with EE in a non-clinical sample. Two-hundred-and-fifty participants completed measures of EE, self-criticism/ self-reassurance, locus of control, interpersonal functioning and personality. Higher scores on the self-criticism and interpersonal difficulties scales and lower scores on the ability to self-reassure scale were associated with both higher EE-Criticism and EOI. Having a more external locus of control was also associated with higher EOI, and higher EE-Criticism with being less open. This knowledge can be used to identify profiles of caregivers who may benefit from additional, targeted therapeutic interventions. The findings suggest that these personality characteristics warrant further investigation in longitudinal studies looking at the development of EE. Part Three is a critical appraisal of the research process. It considers issues pertaining to the construct of EE and how they impacted on the thesis. It also reflects on the methodological choices that were made and how things might have been done differently, and puts forward suggestions for future research

Modeling age-related differences in immediate memory using SIMPLE

In the SIMPLE model (Scale Invariant Memory and Perceptual Learning), performance on memory tasks is determined by the locations of items in multidimensional space, and better performance is associated with having fewer close neighbors. Unlike most previous simulations with SIMPLE, the ones reported here used measured, rather than assumed, dimensional values. The data to be modeled come from an experiment in which younger and older adults recalled lists of acoustically confusable and nonconfusable items. A multidimensional scaling solution based on the memory confusions was obtained. SIMPLE accounted for the overall difference in performance both between the two age groups and, within each age group, the overall difference between acoustically confusable and nonconfusable items in terms of the MDS coordinates. Moreover, the model accounted for the serial position functions and error gradients. Finally, the generality of the model’s account was examined by fitting data from an already published study. The data and the modeling support the hypothesis that older adults’ memory may be worse, in part, because of altered representations due to age-related auditory perceptual deficits

Fixation to features and neural processing of facial expressions in a gender discrimination task

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.bandc.2015.05.007. © 2015. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Early face encoding, as reflected by the N170 ERP component, is sensitive to fixation to the eyes. Whether this sensitivity varies with facial expressions of emotion and can also be seen on other ERP components such as P1 and EPN, was investigated. Using eye-tracking to manipulate fixation on facial features, we found the N170 to be the only eye-sensitive component and this was true for fearful, happy and neutral faces. A different effect of fixation to features was seen for the earlier P1 that likely reflected general sensitivity to face position. An early effect of emotion (∼120 ms) for happy faces was seen at occipital sites and was sustained until ∼350 ms post-stimulus. For fearful faces, an early effect was seen around 80 ms followed by a later effect appearing at ∼150 ms until ∼300 ms at lateral posterior sites. Results suggests that in this emotion-irrelevant gender discrimination task, processing of fearful and happy expressions occurred early and largely independently of the eye-sensitivity indexed by the N170. Processing of the two emotions involved different underlying brain networks active at different times

Facial expression discrimination varies with presentation time but not with fixation on features: A backward masking study using eye-tracking

This is an Accepted Manuscript of an article published by Taylor & Francis in Cognition and Emotion on 23 Sep 2013, available online: http://www.tandfonline.com/10.1080/02699931.2013.812557.The current study investigated the effects of presentation time and fixation to expression-specific diagnostic features on emotion discrimination performance, in a backward masking task. While no differences were found when stimuli were presented for 16.67 ms, differences between facial emotions emerged beyond the happy-superiority effect at presentation times as early as 50 ms. Happy expressions were best discriminated, followed by neutral and disgusted, then surprised, and finally fearful expressions presented for 50 and 100 ms. While performance was not improved by the use of expression-specific diagnostic facial features, performance increased with presentation time for all emotions. Results support the idea of an integration of facial features (holistic processing) varying as a function of emotion and presentation time.This study was supported by the Canadian Institutes for Health Research (CIHR)the Canada Foundation for Innovation (CFI)the Ontario Research Fund (ORF)and the Canada Research Chair (CRC) program to RJI

A Remember-Know Analysis of the Semantic Serial Position Function

Did the serial position functions observed in certain semantic memory tasks (e.g., remembering the order of books or films) arise because they really tapped episodic memory? To address this issue, participants were asked to make "remember-know" judgments as they reconstructed the release order of the 7 Harry Potter books and 2 sets of movies. For both classes of stimuli, the "remember" and "know" serial position functions were indistinguishable, and all showed the characteristic U-shape with marked primacy and recency effects. These results are inconsistent with a multiple memory systems view, which predicts recency effects only for "remember" responses and no recency effects for "know" responses. However, the data were consistent with a general memory principle account: the relative distinctiveness principle. According to this view, performance on both episodic and semantic memory tasks arises from the same type of processing: Items that are more separated from their close neighbors in psychological space at the time of recall will be better remembered