Using perspective to resolve reference: the impact of cognitive load and motivation

Research has demonstrated a link between perspective-taking and working memory. Here we used eye-tracking to examine the time course with which working memory load (WML) influences perspective-taking ability in a referential communication task, and how motivation to take another’s perspective modulates these effects.  In Experiment 1, where there was no reward or time-pressure, listeners only showed evidence of incorporating perspective knowledge during integration of the target object, but did not anticipate reference to this Common Ground object during the pre-target noun period. WML did not affect this perspective use. In Experiment 2 - where a reward for speed and accuracy was applied - listeners used perspective cues to disambiguate the target object from the competitor object from the earliest moments of processing (i.e. during the pre-target noun period)- but only under low load. Under high load, responses were comparable with the control condition, where both objects were in common ground. Furthermore, attempts to initiate perspective-relevant responses under high load led to impaired recall on the concurrent WML task, indicating that perspective-relevant responses were drawing on limited cognitive resources. These results show that when there is ambiguity, perspective cues guide rapid referential interpretation when there is sufficient motivation and sufficient cognitive resources

Eye-tracking reveals the cost of switching between self and other perspectives in a visual perspective-taking task.

Previous studies have shown that while people can rapidly and accurately compute their own and other people's visual perspectives, they experience difficulty ignoring the irrelevant perspective when the two perspectives differ. We used the 'avatar' perspective-taking task to examine the mechanisms that underlie these egocentric (i.e. interference from their own perspective) and altercentric (i.e. interference from the other person's perspective) tendencies. Participants were eye-tracked as they verified the number of discs in a visual scene according to either their own or an on-screen avatar's perspective. Crucially in some trials the two perspectives were inconsistent (i.e. each saw a different number of discs), while in others they were consistent. To examine the effect of perspective switching, performance was compared for trials that were preceded with the same versus different perspective cue. We found that altercentric interference can be reduced or eliminated when participants stick with their own perspective across consecutive trials. Our eye- tracking analyses revealed distinct fixation patterns for self and other perspective-taking, suggesting that consistency effects in this paradigm are driven by implicit mentalising of what others can see, and not automatic directional cues from the avatar

Streams of data from drops of water: 21st century molecular microbial ecology

Microorganisms are ubiquitous and represent a taxonomically and functionally diverse component of freshwater environments of significant ecological importance. The bacteria, archaea, and microbial eukarya in freshwater systems support a range of ecosystem processes and functions, including mediating all major biogeochemical cycles, and therefore regulate the flow of multiple ecosystem services. Yet relative to conspicuous higher taxa, microbial ecology remains poorly understood. As the anthropocene progresses, the demand for freshwater–ecosystem services is both increasing with growing human population density, and by association, increasingly threatened from multiple and often interacting stressors, such as climate change, eutrophication, and chemical pollution. Thus, it is imperative to understand the ecology of microorganisms and their functional role in freshwater ecosystems if we are to manage the future of these environments effectively. To do this, researchers have developed a vast array of molecular tools that can illuminate the diversity, composition, and activity of microbial communities. Within this primer, we discuss the history of molecular approaches in microbial ecology, and highlight the scope of questions that these methods enable researchers to address. Using some recent case studies, we describe some exemplar research into the microbial ecology of freshwater systems, and emphasize how molecular methods can provide novel ecological insights. Finally, we detail some promising developments within this research field, and how these might shape the future research landscape of freshwater microbial ecology

Uncommon cause for anterior knee pain - Aggressive aneurysmal bone cyst of the patella

A 56-year-old man presented with a two month history of increasing anterior knee pain without previous trauma. As usual we recommended physiotherapy with stretching exercises of the quadriceps muscle. Since symptoms did not improve after 6 weeks MRI was performed. Surprisingly a hyperintense lobulated mass of the patella with small fluid-filled cavities at the inferior pole was revealed. We performed an open biopsy to exclude any malignancy and diagnosed an aneurysmal bone cyst. Further examination with CT scans showed an aggressive behaviour with cortical breakthrough

The impact of the demographic transition on dengue in Thailand: Insights from a statistical analysis and mathematical modeling

Background: An increase in the average age of dengue hemorrhagic fever (DHF) cases has been reported in Thailand. The cause of this increase is not known. Possible explanations include a reduction in transmission due to declining mosquito populations, declining contact between human and mosquito, and changes in reporting. We propose that a demographic shift toward lower birth and death rates has reduced dengue transmission and lengthened the interval between large epidemics. Methods and Findings: Using data from each of the 72 provinces of Thailand, we looked for associations between force of infection (a measure of hazard, defined as the rate per capita at which susceptible individuals become infected) and demographic and climactic variables. We estimated the force of infection from the age distribution of cases from 1985 to 2005. We find that the force of infection has declined by 2% each year since a peak in the late 1970s and early 1980s. Contrary to recent findings suggesting that the incidence of DHF has increased in Thailand, we find a small but statistically significant decline in DHF incidence since 1985 in a majority of provinces. The strongest predictor of the change in force of infection and the mean force of infection is the median age of the population. Using mathematical simulations of dengue transmission we show that a reduced birth rate and a shift in the population's age structure can explain the shift in the age distribution of cases, reduction of the force of infection, and increase in the periodicity of multiannual oscillations of DHF incidence in the absence of other changes. Conclusions: Lower birth and death rates decrease the flow of susceptible individuals into the population and increase the longevity of immune individuals. The increase in the proportion of the population that is immune increases the likelihood that an infectious mosquito will feed on an immune individual, reducing the force of infection. Though the force of infection has decreased by half, we find that the critical vaccination fraction has not changed significantly, declining from an average of 85% to 80%. Clinical guidelines should consider the impact of continued increases in the age of dengue cases in Thailand. Countries in the region lagging behind Thailand in the demographic transition may experience the same increase as their population ages. The impact of demographic changes on the force of infection has been hypothesized for other diseases, but, to our knowledge, this is the first observation of this phenomenon

From z>6 to z~2: Unearthing Galaxies at the Edge of the Dark Ages

Galaxies undergoing formation and evolution can now be observed over a time baseline of some 12 Gyr. An inherent difficulty with high-redshift observations is that the objects are very faint and the best resolution (HST) is only ~0.5 kpc. Such studies thereby combine in a highly synergistic way with the great detail that can be obtained for nearby galaxies. 3 new developments are highlighted. First is the derivation of stellar masses for galaxies from SEDs using HST and now Spitzer data, and dynamical masses from both sub-mm observations of CO lines and near-IR observations of optical lines like Halpha. A major step has been taken with evidence that points to the z~2-3 LBGs having masses that are a few x 10^10 Msolar. Second is the discovery of a population of evolved red galaxies at z~2-3 which appear to be the progenitors of the more massive early-type galaxies of today, with dynamical masses around a few x 10^11 Msolar. Third are the remarkable advances that have occurred in characterizing dropout galaxies to z~6 and beyond, < 1 Gyr from recombination. The HST ACS has played a key role here, with the dropout technique being applied to i & z images in several deep ACS fields, yielding large samples of these objects. This has allowed a detailed determination of their properties and meaningful comparisons against lower-z samples. The use of cloning techniques has overcome many of the strong selection biases affecting the study of these objects. A clear trend of size with redshift has been identified, and its impact on the luminosity density and SFR estimated. There is a significant though modest decrease in the SFR from z~2.5 to z~6. The latest data also allow for the first robust determination of the LF at z~6. Finally, the latest UDF ACS and NICMOS data has resulted in the detection of some galaxies at z~7-8.Comment: 18 pages, 8 figures. To appear in Penetrating Bars through Masks of Cosmic Dust: The Hubble Tuning Fork Strikes a New Note, eds. D. Block, K. Freeman, R. Groess, I. Puerari, & E.K. Block (Dordrecht: Kluwer), in pres

Dynamics of multi-stage infections on networks

This paper investigates the dynamics of infectious diseases with a nonexponentially distributed infectious period. This is achieved by considering a multistage infection model on networks. Using pairwise approximation with a standard closure, a number of important characteristics of disease dynamics are derived analytically, including the final size of an epidemic and a threshold for epidemic outbreaks, and it is shown how these quantities depend on disease characteristics, as well as the number of disease stages. Stochastic simulations of dynamics on networks are performed and compared to output of pairwise models for several realistic examples of infectious diseases to illustrate the role played by the number of stages in the disease dynamics. These results show that a higher number of disease stages results in faster epidemic outbreaks with a higher peak prevalence and a larger final size of the epidemic. The agreement between the pairwise and simulation models is excellent in the cases we consider

The effect of Ku on telomere replication time is mediated by telomere length but is independent of histone tail acetylation

Peer reviewedPublisher PD

Tracking the impact of depression in a perspective-taking task

Research has identified impairments in Theory of Mind (ToM) abilities in depressed patients, particularly in relation to tasks involving empathetic responses and belief reasoning. We aimed to build on this research by exploring the relationship between depressed mood and cognitive ToM, specifically visual perspective-taking ability. High and low depressed participants were eye-tracked as they completed a perspective-taking task, in which they followed the instructions of a ‘director’ to move target objects (e.g. a “teapot with spots on”) around a grid, in the presence of a temporarily-ambiguous competitor object (e.g. a “teapot with stars on”). Importantly, some of the objects in the grid were occluded from the director’s (but not the participant’s) view. Results revealed no group-based difference in participants’ ability to use perspective cues to identify the target object. All participants were faster to select the target object when the competitor was only available to the participant, compared to when the competitor was mutually available to the participant and director. Eye-tracking measures supported this pattern, revealing that perspective directed participants’ visual search immediately upon hearing the ambiguous object’s name (e.g. “teapot”). We discuss how these results fit with previous studies that have shown a negative relationship between depression and ToM