785 research outputs found

    Decoding images in the mind's eye : the temporal dynamics of visual imagery

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    Mental imagery is the ability to generate images in the mind in the absence of sensory input. Both perceptual visual processing and internally generated imagery engage large, overlapping networks of brain regions. However, it is unclear whether they are characterized by similar temporal dynamics. Recent magnetoencephalography work has shown that object category information was decodable from brain activity during mental imagery, but the timing was delayed relative to perception. The current study builds on these findings, using electroencephalography to investigate the dynamics of mental imagery. Sixteen participants viewed two images of the Sydney Harbour Bridge and two images of Santa Claus. On each trial, they viewed a sequence of the four images and were asked to imagine one of them, which was cued retroactively by its temporal location in the sequence. Time-resolved multivariate pattern analysis was used to decode the viewed and imagined stimuli. Although category and exemplar information was decodable for viewed stimuli, there were no informative patterns of activity during mental imagery. The current findings suggest stimulus complexity, task design and individual differences may influence the ability to successfully decode imagined images. We discuss the implications of these results in the context of prior findings of mental imagery

    Capacity for movement is an organisational principle in object representations

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    The ability to perceive moving objects is crucial for threat identification and survival. Recent neuroimaging evidence has shown that goal-directed movement is an important element of object processing in the brain. However, prior work has primarily used moving stimuli that are also animate, making it difficult to disentangle the effect of movement from aliveness or animacy in representational categorisation. In the current study, we investigated the relationship between how the brain processes movement and aliveness by including stimuli that are alive but still (e.g., plants), and stimuli that are not alive but move (e.g., waves). We examined electroencephalographic (EEG) data recorded while participants viewed static images of moving or non-moving objects that were either natural or artificial. Participants classified the images according to aliveness, or according to capacity for movement. Movement explained significant variance in the neural data over and above that of aliveness, showing that capacity for movement is an important dimension in the representation of visual objects in humans

    Genome sequences of 12 bacterial isolates obtained from the urine of pregnant women

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    The presence of bacteria in urine can pose significant risks during pregnancy. However, there are few reference genome strains for many common urinary bacteria. We isolated 12 urinary strains of Streptococcus, Staphylococcus, Citrobacter, Gardnerella, and Lactobacillus. These strains and their genomes are now available to the research community

    Overlapping neural representations for the position of visible and imagined objects

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    Humans can covertly track the position of an object, even if the object is temporarily occluded. What are the neural mechanisms underlying our capacity to track moving objects when there is no physical stimulus for the brain to track? One possibility is that the brain 'fills-in' information about imagined objects using internally generated representations similar to those generated by feed-forward perceptual mechanisms. Alternatively, the brain might deploy a higher order mechanism, for example using an object tracking model that integrates visual signals and motion dynamics. In the present study, we used EEG and time-resolved multivariate pattern analyses to investigate the spatial processing of visible and imagined objects. Participants tracked an object that moved in discrete steps around fixation, occupying six consecutive locations. They were asked to imagine that the object continued on the same trajectory after it disappeared and move their attention to the corresponding positions. Time-resolved decoding of EEG data revealed that the location of the visible stimuli could be decoded shortly after image onset, consistent with early retinotopic visual processes. For processing of unseen/imagined positions, the patterns of neural activity resembled stimulus-driven mid-level visual processes, but were detected earlier than perceptual mechanisms, implicating an anticipatory and more variable tracking mechanism. Encoding models revealed that spatial representations were much weaker for imagined than visible stimuli. Monitoring the position of imagined objects thus utilises similar perceptual and attentional processes as monitoring objects that are actually present, but with different temporal dynamics. These results indicate that internally generated representations rely on top-down processes, and their timing is influenced by the predictability of the stimulus.Comment: All data and analysis code for this study are available at https://osf.io/8v47t

    Dormant season warming amplifies daytime CO2 emissions from a temperate urban salt marsh

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    Salt marshes provide many important ecosystem services, key among them being carbon sequestration. However, a large degree of uncertainty remains in salt marsh carbon budgets, particularly during colder months of the year when salt marsh microbial and vegetative activity is assumed to dormant. We also lack data on urban systems. In this study, we used an easily portable carbon dioxide sensor package to directly measure net carbon dioxide (CO2) fluxes throughout the winter in a temperate, urban salt marsh. We sampled across the dormant season both on normal (cold) temperature days and on days that were anomalously warm (defined here as air temperatures 2.8°C above the long-term average). We demonstrated that median (±mad) daytime CO2 fluxes doubled on the warm days, compared to cold days (1.7 ± 2 mmol m−2 h−1, 0.7 ± 1.3 mmol m−2 h−1, respectively). We also show that net CO2 emissions scaled with soil temperature. The high day-to-day variability, however, implies that infrequent or sparse measurements cannot sufficiently capture the temporal dynamics of dormant season salt marsh net CO2 fluxes. The magnitude of the net CO2 source from our sampling during the dormant season leads us to hypothesize that, as mean annual temperatures continue to increase, dormant season CO2 emissions from salt marshes will increasingly offset growing season carbon dioxide uptake. This change compromises the carbon sequestration capacity, and therefore the climate mitigation potential of these ecosystems. Future studies should focus on quantifying the impact of dormant season CO2, and other greenhouse gases on salt marsh carbon budgets

    A small constellation: risk factors informing police perceptions of domestic abuse

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    Police in the United States (US) and the United Kingdom (UK) now routinely use risk assessment tools to identify common risk factors for re-abuse and lethality when responding to domestic abuse. Nevertheless, little is known about the extent to which officers understand and perceive the importance of factors commonly included on risk assessment tools for predicting future abuse. This study attempts to shed some light into this area of research by exploring the responses of 720 British and American police officers to questions regarding how important and how essential various risk factors are for evaluating the level of risk or harm a victim of domestic abuse may face in the future. Findings indicated that British and American officers were largely in agreement about a small constellation of risk factors that they considered integral to the risk assessment process: using or threatening to use a weapon; strangulation; physical assault resulting in injury and escalation of abuse. The results revealed that officers’ country of employment, rather than their demographic characteristics or experience policing domestic abuse, was a particularly influential predictor of their perceptions, and that both the situational context and the victim’s perception about risk are important in domestic abuse risk assessment

    Under the radar: policing non-violent domestic abuse in the US and UK

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    Physical violence is but one of many tools that may be used to gain greater power within intimate relationships, yet the legal response has been critiqued for failing to recognise and respond to the full spectrum of abusive behaviours, such as coercive control. Using a sample of police officers from the United States (US) and the United Kingdom (UK), the current study utilises hypothetical vignettes to assess police officers’ perceptions of domestic abuse, including those incidents that are not necessarily physically violent, but involve stalking and other coercive, controlling behaviours that are harmful and require intervention. Within and between-country similarities and differences were analysed. Findings revealed that the majority of officers in both countries possessed a good level of understanding of domestic abuse and how they should respond to it – amidst and beyond the physical violence. However, our analysis of both quantitative and qualitative data also showed that the use of physical violence is at the forefront of many officers’ expectations about domestic abuse, and that when physical violence is absent, the police response is less proactive. Our study finds some support for the idea that non-physical abuse does go “under the radar” to some extent for some officers, and that this is more the case for American officers than their British counterparts. Findings are discussed in terms of context of the research sites and implications for policy, practice and future researc

    Using a descriptive social norm to increase vegetable selection in workplace restaurant settings

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    Objective: Recent work has shown that exposure to social norm messages may enhance the consumption of vegetables. However, the majority of this work has been conducted in laboratories, often with student populations. Little is known about whether this approach can be successfully used in other contexts. In this study, a poster featuring a message based on social norms was tested to examine whether it could increase and maintain the purchase of meals with vegetables in workplace restaurants. Methods: A pretest-posttest design with three phases was used in three workplace restaurants in the United Kingdom. The first two weeks formed the pre-intervention phase, the second two weeks the intervention phase, and the last two weeks the post-intervention phase. During the intervention phase only, posters containing a social norm message relaying information about vegetable purchases of other diners were placed in each restaurant. The main outcome measure was the percentage of meals purchased with vegetables, which was analysed using Pearson’s chi-squared test. Results: Participants were judged to be: male (57%), not overweight (75%) and under the age of 60 (98%). The intervention was positively associated with the percentage of meals purchased with vegetables: baseline vs. intervention (60% vs. 64% of meals purchased with vegetables; p < 0.01); intervention vs. post-intervention (64% vs. 67% of meals purchased with vegetables; p < 0.01); and baseline vs. post-intervention (60% vs. 67% of meals purchased with vegetables; p < 0.001). Conclusions: Social norm messages may increase the purchase of vegetables in workplace settings. PsycINFO Database Record (c) 2017 APA, all rights reserved
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