Melbourne School of Psychological Sciences - Research Publications

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    Altered task-related decoupling of the rostral anterior cingulate cortex in depression.
    Leonards, CA ; Harrison, BJ ; Jamieson, AJ ; Agathos, J ; Steward, T ; Davey, CG (Elsevier BV, 2024)
    Dysfunctional activity of the rostral anterior cingulate cortex (rACC) - an extensively connected hub region of the default mode network - has been broadly linked to cognitive and affective impairments in depression. However, the nature of aberrant task-related rACC suppression in depression is incompletely understood. In this study, we sought to characterize functional connectivity of rACC activity suppression ('deactivation') - an essential feature of rACC function - during external task engagement in depression. Specifically, we aimed to explore neural patterns of functional decoupling and coupling with the rACC during its task-driven suppression. We enrolled 81 15- to 25-year-old young people with moderate-to-severe major depressive disorder (MDD) before they commenced a 12-week clinical trial that assessed the effectiveness of cognitive behavioral therapy plus either fluoxetine or placebo. Ninety-four matched healthy controls were also recruited. Participants completed a functional magnetic resonance imaging face matching task known to elicit rACC suppression. To identify brain regions associated with the rACC during its task-driven suppression, we employed a seed-based functional connectivity analysis. We found MDD participants, compared to controls, showed significantly reduced 'decoupling' of the rACC with extended task-specific regions during task performance. Specifically, less decoupling was observed in the occipital and fusiform gyrus, dorsal ACC, medial prefrontal cortex, cuneus, amygdala, thalamus, and hippocampus. Notably, impaired decoupling was apparent in participants who did not remit to treatment, but not treatment remitters. Further, we found MDD participants showed significant increased coupling with the anterior insula cortex during task engagement. Our findings indicate that aberrant task-related rACC suppression is associated with disruptions in adaptive neural communication and dynamic switching between internal and external cognitive modes that may underpin maladaptive cognitions and biased emotional processing in depression.
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    Motivators of e-cigarette use among Australian adolescents, young adults, and adults
    Thoonen, KAHJ ; Jongenelis, MI (PERGAMON-ELSEVIER SCIENCE LTD, 2024-01)
    OBJECTIVE: There is limited research examining motivators of e-cigarette use among never smokers, a group for whom vaping has no benefits and many harms. To inform programs and policies that aim to prevent initiation and encourage cessation of e-cigarette use, this study investigated reasons for intended use, initiation, and continued use of e-cigarettes among various age and user groups in Australia. METHODS: An online survey was administered to 4617 respondents. Never users of e-cigarettes and never smokers who reported intending to try e-cigarettes (n = 348), current e-cigarette users and never smokers (n = 121), and current e-cigarette users and current smokers (n = 354) were of interest to this study. RESULTS: Among never smokers, curiosity was the most commonly reported reason for intended use and use initiation, whereas the taste of e-cigarettes and their appealing flavours were the most frequently reported motivators of current e-cigarette use. Among smokers, taste and flavourings were the most commonly reported motivators of current use, not smoking cessation. Adolescents and young adults in most user groups were more likely than adults to report using e-cigarettes out of curiosity and because they taste good, whereas adults were more likely to use for smoking cessation purposes and because they perceived e-cigarettes to be more acceptable and cheaper than tobacco cigarettes. CONCLUSIONS: Results suggest that (i) prohibiting flavourings and (ii) restricting advertising that highlights the pleasurable effects of e-cigarettes could constitute potential means of preventing e-cigarette initiation and encouraging cessation among never smokers, especially adolescents.
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    Inductive reasoning in humans and large language models
    Han, SJ ; Ransom, KJ ; Perfors, A ; Kemp, C (ELSEVIER, 2024-01)
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    Neural correlates of confidence during decision formation in a perceptual judgment task.
    Ko, YH ; Zhou, A ; Niessen, E ; Stahl, J ; Weiss, PH ; Hester, R ; Bode, S ; Feuerriegel, D (Elsevier BV, 2024-02-09)
    When we make a decision, we also estimate the probability that our choice is correct or accurate. This probability estimate is termed our degree of decision confidence. Recent work has reported event-related potential (ERP) correlates of confidence both during decision formation (the centro-parietal positivity component; CPP) and after a decision has been made (the error positivity component; Pe). However, there are several measurement confounds that complicate the interpretation of these findings. More recent studies that overcome these issues have so far produced conflicting results. To better characterise the ERP correlates of confidence we presented participants with a comparative brightness judgment task while recording electroencephalography. Participants judged which of two flickering squares (varying in luminance over time) was brighter on average. Participants then gave confidence ratings ranging from "surely incorrect" to "surely correct". To elicit a range of confidence ratings we manipulated both the mean luminance difference between the brighter and darker squares (relative evidence) and the overall luminance of both squares (absolute evidence). We found larger CPP amplitudes in trials with higher confidence ratings. This association was not simply a by-product of differences in relative evidence (which covaries with confidence) across trials. We did not identify postdecisional ERP correlates of confidence, except when they were artificially produced by pre-response ERP baselines. These results provide further evidence for neural correlates of processes that inform confidence judgments during decision formation.
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    Directive Explanations for Actionable Explainability in Machine Learning Applications
    Singh, R ; Miller, T ; Lyons, H ; Sonenberg, L ; Velloso, E ; Vetere, F ; Howe, P ; Dourish, P (ASSOC COMPUTING MACHINERY, 2023-12)
    In this article, we show that explanations of decisions made by machine learning systems can be improved by not only explaining why a decision was made but also explaining how an individual could obtain their desired outcome. We formally define the concept of directive explanations (those that offer specific actions an individual could take to achieve their desired outcome), introduce two forms of directive explanations (directive-specific and directive-generic), and describe how these can be generated computationally. We investigate people’s preference for and perception toward directive explanations through two online studies, one quantitative and the other qualitative, each covering two domains (the credit scoring domain and the employee satisfaction domain). We find a significant preference for both forms of directive explanations compared to non-directive counterfactual explanations. However, we also find that preferences are affected by many aspects, including individual preferences and social factors. We conclude that deciding what type of explanation to provide requires information about the recipients and other contextual information. This reinforces the need for a human-centered and context-specific approach to explainable AI.
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    Support for nicotine reduction in cigarettes: findings from the 2016 and 2020 ITC Four Country Smoking and Vaping Surveys
    Fairman, RT ; Cho, YJ ; Popova, L ; Cummings, KM ; Smith, TT ; Fong, GT ; Gravely, S ; Borland, R ; Mcneill, A ; Gartner, CE ; Morphett, K ; Thrasher, JF (BMJ PUBLISHING GROUP, 2023-12-08)
    INTRODUCTION: The USA and New Zealand have sought to establish a product standard to set a maximum nicotine level for cigarettes to reduce their addictiveness. This study examined support for very low nicotine cigarettes (VLNCs) in Australia, Canada, England and the USA between 2016 and 2020. METHODS: Repeated cross-sectional data were analysed from participants who currently smoke, formerly smoked or vaped and/or currently vape in the 2016 (n=11 150) and/or 2020 (n=5432) International Tobacco Control (ITC) Four Country Smoking and Vaping Survey. Respondents were asked if they would support a law that reduces the amount of nicotine in cigarettes to make them less addictive. Adjusted and weighted logistic regression analyses estimated the prevalence and predictors of support, such as country, age, sex, education, income, race and smoking/vaping status for VLNCs (support vs oppose/do not know). RESULTS: A majority of respondents supported a VLNC law, with support highest in Canada (69%; 2016 and 2020 combined), followed by England (61%), Australia (60%) and the USA (58%). Overall, support decreased from 62% in 2016 to 59% in 2020 (p=0.004), which did not differ by country. Levels of support differed by smoking/vaping status, where those who exclusively smoked daily showed the lowest level of support (59%) and those who exclusively vaped non-daily had the highest level of support (72%). CONCLUSION: More than half of respondents in all four countries-including those who smoked daily-supported a hypothetical VLNC standard to render cigarettes less addictive. It is important to examine if support is sustained after policies are implemented.
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    An analysis of real-time suicidal ideation and its relationship with retrospective reports among young people with borderline personality disorder
    Andrewes, HE ; Cavelti, M ; Hulbert, C ; Cotton, SM ; Betts, JK ; Jackson, HJ ; McCutcheon, L ; Gleeson, J ; Davey, CG ; Chanen, AM (WILEY, 2024-02-20)
    INTRODUCTION: This study aimed to analyze the real-time variability of suicidal ideation intensity and the relationship between real-time and retrospective reports of suicidal ideation made on the Beck Scale for Suicidal Ideation (BSS), among young people with borderline personality disorder (BPD). METHODS: Young people (15-25-year olds) with BPD (N = 46), recruited from two government-funded mental health services, rated the intensity of their suicidal ideation six times per day for 7 days before completing the BSS. RESULTS: For 70% of participants, suicidal ideation changed in intensity approximately five times across the week, both within and between days. BSS ratings were most highly correlated with the highest real-time ratings of suicidal ideation. However, this was not significantly different from the relationship between the BSS and both the average and most recent ratings. Median ratings of suicidal ideation intensity were higher on the BSS compared with an equivalent question asked in real time. CONCLUSION: Findings suggest that young people with BPD experience high levels of fluctuation in their intensity of suicidal ideation across a week and that retrospective reports of suicidal ideation might be more reflective of the most intense experience of suicidal ideation across the week.
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    Twenty-year associations between disordered eating behaviors and sociodemographic features in a multiple cross-sectional sample
    Santana, DD ; Mitchison, D ; Mannan, H ; Griffiths, S ; Appolinario, JC ; da Veiga, GV ; Touyz, S ; Hay, P (CAMBRIDGE UNIV PRESS, 2023-08)
    BACKGROUND: Disordered eating behaviors (DEB) impact on health and wellbeing worldwide. This study aimed to examine sociodemographic trends in the prevalence of DEB over 20 years in the Australian general population. METHODS: Data were derived from five sequential cross-sectional surveys (1998, 2008, 2009, 2016 and 2017) with population-representative samples of adults and adolescents residing in South Australia (N = 15 075). DEBs investigated were objective binge eating (OBE), strict dieting/fasting, and purging. Sociodemographic data included gender, age, educational level, work and marital status, and residence. RESULTS: OBE prevalence increased significantly. Strict dieting/fasting also increased from 1998 to 2008/9 but remained stable between 2008/9 and 2016/7. Purging prevalence did not change significantly over time. All survey years were associated with a significantly higher odds of OBE, and strict diet/fasting compared to 1998. Lower age, a higher Accessibility Remoteness Index of Australia (ARIA) score, higher body mass index (BMI), higher educational attainment, and not being in a married or de facto relationship were independently associated with greater adjusted odds for endorsing OBE. Younger age, female gender, and higher BMI were also independently associated with greater adjusted odds for endorsing strict dieting/fasting. CONCLUSIONS: The increased prevalence of DEBs in various strata of Australian society has both public health and clinical implications. The results refute the stereotype that eating disorders (EDs) predominantly affect young women. They build impetus for future research on EDs among men and older individuals, with a view to developing tailored public health and clinical interventions for these populations.
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    Mice with an autism-associated R451C mutation in neuroligin-3 show intact attention orienting but atypical responses to methylphenidate and atomoxetine in the mouse-Posner task
    Li, S ; May, C ; Pang, TY ; Churilov, L ; Hannan, AJ ; Johnson, KA ; Burrows, EL (SPRINGER, 2024-03)
    RATIONALE: Atypical attention orienting has been associated with some autistic symptoms, but the neural mechanisms remain unclear. The human Posner task, a classic attention orienting paradigm, was recently adapted for use with mice, supporting the investigation of the neurobiological underpinnings of atypical attention orienting in preclinical mouse models. OBJECTIVE: The current study tested mice expressing the autism-associated R451C gene mutation in neuroligin-3 (NL3) on the mouse-Posner (mPosner) task. METHODS: NL3R451C and wild-type (WT) mice were trained to respond to a validly or invalidly cued target on a touchscreen. The cue was a peripheral non-predictive flash in the exogenous task and a central spatially predictive image in the endogenous task. The effects of dopaminergic- and noradrenergic-modulating drugs, methylphenidate and atomoxetine, on task performance were assessed. RESULTS: In both tasks, mice were quicker and more accurate in the validly versus invalidly cued trials, consistent with results in the human Posner task. NL3R451C and WT mice showed similar response times and accuracy but responded differently when treated with methylphenidate and atomoxetine. Methylphenidate impaired exogenous attention disengagement in NL3R451C mice but did not significantly affect WT mice. Atomoxetine impaired endogenous orienting in WT mice but did not significantly affect NL3R451C mice. CONCLUSIONS: NL3R451C mice demonstrated intact attention orienting but altered responses to the pharmacological manipulation of the dopaminergic and noradrenergic networks. These findings expand our understanding of the NL3R451C mutation by suggesting that this mutation may lead to selective alterations in attentional processes.
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    Examining the facets of mindful engagement and mind wandering in nature
    Macaulay, R ; Johnson, K ; Lee, K ; Williams, K (Elsevier BV, 2024-03)
    Mindfulness and mind wandering may both enhance the psychological outcomes of nature experiences. Both states are multi-faceted, with mindfulness involving specific components such as decentering, body awareness, and nonjudgment, and mind wandering involving intentional and spontaneous mind wandering. These facets may differentially predict psychological outcomes of nature experiences, however these associations have not been tested. In this study we examined facets of mindfulness and mind wandering in nature and tested their associations with outcomes of psychological restoration and nature connection. We also tested the effects of situational factors on these engagement facets in nature. We conducted an experiment in which participants were instructed on how to engage with nature during a 20min experience in nearby nature and completed online surveys before and after the outdoor experience. Participants were allocated into one of four groups, each given different engagement instructions. We used measures of state mindfulness that assessed three facets – decentering, nonjudgment, and body awareness – and measures of mind wandering that assessed two facets – mindlessness, and deliberate mind wandering. Regression analyses revealed associations between these facets and outcomes of the nature experience; decentering and deliberate mind wandering were associated with positive outcomes, including stronger nature connection and positive affect, and nonjudgment was associated with higher negative affect. Further analyses revealed perceived restorativeness and other situational factors such as affective state influenced engagement during the nature experience. These results demonstrate the value of deconstructing mindfulness and mind wandering in nature to explore facets that have beneficial or adverse effects on psychological outcomes. We conclude with practical directions for nature-based engagement interventions that can target the beneficial components of these practices in different contexts.