ORCID Profile
0000-0002-4486-8667
Current Organisation
University of Melbourne
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Informa UK Limited
Date: 27-09-2017
Publisher: Springer Science and Business Media LLC
Date: 21-07-2022
DOI: 10.1007/S00127-022-02340-9
Abstract: Rail level crossing removals to improve transport performance across metropolitan Melbourne (state of Victoria) resulted in new rail fencing and grade-separation of tracks from the surrounding environment at several sites. These design changes restricted pedestrian access to the rail tracks, which is a countermeasure known to prevent railway suicide in other settings. We examined whether any such suicide prevention effect followed the removals. We used a multiple-arm pre-post design to test whether a decrease in monthly frequency of railway suicides occurred at level crossing removal sites (intervention sites), compared to randomly matched sites where level crossings had not yet been removed (control sites). We used data available in the Victorian Suicide Register covering the period 1st January 2008 to 30th June 2021. The mean monthly number of railway suicides decreased by 68% within a 500 m radius of intervention sites (RR: 0.32 CI 95% 0.11–0.74) and by 61% within a 1000 m radius of intervention sites (RR: 0.39 CI 95% 0.21–0.68). There was no evidence that the mean monthly number of railway suicides changed at the control sites, either within a 500 m radius (RR: 0.88 CI 95% 0.47–1.56) or a 1000 m radius (RR: 0.82 CI 95% 0.52–1.26). The reduction in railway suicides at locations where level crossings were removed, demonstrates the suicide prevention benefits that can be derived from a major infrastructure project even if not initially intended. Planning for major infrastructure projects should include consideration of these benefits, with designs incorporating features to maximise suicide prevention impact.
Publisher: Wiley
Date: 17-03-2010
DOI: 10.1111/J.1551-6709.2009.01090.X
Abstract: This paper compares two explanations of the process by which human communication systems evolve: iterated learning and social collaboration. It then reports an experiment testing the social collaboration account. Participants engaged in a graphical communication task either as a member of a community, where they interacted with seven different partners drawn from the same pool, or as a member of an isolated pair, where they interacted with the same partner across the same number of games. Participants' horizontal, pair-wise interactions led "bottom up" to the creation of an effective and efficient shared sign system in the community condition. Furthermore, the community-evolved sign systems were as effective and efficient as the local sign systems developed by isolated pairs. Finally, and as predicted by a social collaboration account, and not by an iterated learning account, interaction was critical to the creation of shared sign systems, with different isolated pairs establishing different local sign systems and different communities establishing different global sign systems.
Publisher: The Royal Society
Date: 17-09-2008
Abstract: This paper assesses whether human communication systems undergo the same progressive adaptation seen in animal communication systems and concrete artefacts. Four experiments compared the fitness of ad hoc sign systems created under different conditions when participants play a graphical communication task. Experiment 1 demonstrated that when participants are organized into interacting communities, a series of signs evolve that enhance in idual learning and promote efficient decoding. No such benefits are found for signs that result from the local interactions of isolated pairs of interlocutors. Experiments 2 and 3 showed that the decoding benefits associated with community evolved signs cannot be attributed to superior sign encoding or detection. Experiment 4 revealed that naive overseers were better able to identify the meaning of community evolved signs when compared with isolated pair developed signs. Hence, the decoding benefits for community evolved signs arise from their greater residual iconicity. We argue that community evolved sign systems undergo a process of communicative selection and adaptation that promotes optimized sign systems. This results from the interplay between sign ersity and a global alignment constraint pairwise interaction introduces a range of competing signs and the need to globally align on a single sign-meaning mapping for each referent applies selection pressure.
Publisher: Human Kinetics
Date: 09-2022
Abstract: There are numerous studies of expert golfers’ thought processes, but few have examined thinking during both shot preparation and execution. This study had skilled golfers ( N = 95, mean handicap = 1.5) complete a mixed-methods survey about their preparation/execution thoughts (a) in usual competitive circumstances and (b) during past experiences of choking. The results provided rare documentation of the ways that highly skilled golfers occupy their minds throughout the whole shot-making process. Moreover, the data allowed comparison of what golfers prefer to focus on and what the sport psychology literature recommends as optimal. The clearest gap that emerged was widespread use of deliberate or multifaceted thought during execution, against classical recommendations to swing with a quiet mind. The examination of choking implied that conscious interference was a more common rationalization for choking than previously reported. Implications for practice are discussed.
Publisher: Informa UK Limited
Date: 14-10-2019
Publisher: Oxford University Press (OUP)
Date: 10-2020
DOI: 10.1093/RPD/NCAA175
Abstract: Children undergoing computed tomography (CT) scans have an increased risk of cancer in subsequent years, but it is unclear how much of the excess risk is due to reverse causation bias or confounding, rather than to causal effects of ionising radiation. An examination of the relationship between excess cancer risk and organ dose can help to resolve these uncertainties. Accordingly, we have estimated doses to 33 different organs arising from over 900 000 CT scans between 1985 and 2005 in our previously described cohort of almost 12 million Australians aged 0–19 years. We used a multi-tiered approach, starting with Medicare billing details for government-funded scans. We reconstructed technical parameters from national surveys, clinical protocols, regulator databases and peer-reviewed literature to estimate almost 28 000 000 in idual organ doses. Doses were age-dependent and tended to decrease over time due to technological improvements and optimisation.
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.JAD.2022.02.021
Abstract: Online searches related to suicide may sometimes be an early proxy indicator for behavioural outcomes. We used interrupted time series regression analyses to examine changes in suicide and resilience-related Google searches worldwide and in the United States during the first 12 months of the COVID-19 pandemic. Searches for the word "suicide" were unchanged worldwide (-1% 95%CI, -12%-11%) and in the US (-7% 95%CI, -15%-2%) with decreased searches for "suicide methods" and increased searches for "how to kill yourself" and for resilience-related terms. This study provides potential evidence that suicides may not increase worldwide during the first year of the pandemic.
Publisher: Public Library of Science (PLoS)
Date: 28-06-2023
DOI: 10.1371/JOURNAL.PONE.0287700
Abstract: The ‘nervous nineties’ is a well-known cricket colloquialism that implies that batting within reach of 100 runs is mentally demanding. Despite common acceptance of this phenomenon, no study has used a historical test cricket dataset to examine how batting behaviour and performance changes on approach to a century. Accordingly, we explored opensource ball-by-ball data from 712 test cricket matches played between 2004 and 2022 to model the regression discontinuity of batting performance metrics either side of 100 runs. Models were fit using multi-level regression, adjusted for the clustering of balls within players (and where possible, the clustering of matches and innings within players). The analysis revealed that runs per ball and the probability of scoring a boundary increased as batters approached 100 runs. This was followed by a decline of -0.18 runs per ball (95% CI -0.22 to -0.14) and a three-percentage point decline (95% CI 2.2 to 3.8) in the probability of a boundary once a batter reached 100. The modelling revealed no evidence of a change in the probability of a dismissal before and after 100. Our results suggest many batters cope effectively with the psychological demands of playing through the nineties, including by batting aggressively and/or opportunistically to swiftly reach the milestone.
Publisher: Springer Science and Business Media LLC
Date: 12-2006
DOI: 10.3758/BF03195930
Abstract: Knowledge partitioning refers to the notion that knowledge can be held in independent and non-overlapping parcels. Partitioned knowledge may cause people to make contradictory decisions for identical problems in different circumstances. We report two experiments that explored the boundary conditions of knowledge partitioning in categorization. The studies examined whether or not people would partition their knowledge (1) when categorization rules were or were not verbalizable and (2) when the to-be-categorized stimuli comprised perceptually separable or integral dimensions. When learning difficulty was controlled, partitioning occurred across all combinations of verbalizability and integrality/separability, underscoring the generality of knowledge partitioning. Partitioning was absent only when the task was rapidly learned and people reached a high level of proficiency, suggesting that task difficulty plays a critical role in the emergence of partitioned knowledge.
No related grants have been discovered for Leo Roberts.