Risk of tipping the overturning circulation due to increasing rates of ice melt.

Central elements of the climate system are at risk for crossing critical thresholds (so-called tipping points) due to future greenhouse gas emissions, leading to an abrupt transition to a qualitatively different climate with potentially catastrophic consequences. Tipping points are often associated with bifurcations, where a previously stable system state loses stability when a system parameter is increased above a well-defined critical value. However, in some cases such transitions can occur even before a parameter threshold is crossed, given that the parameter change is fast enough. It is not known whether this is the case in high-dimensional, complex systems like a state-of-the-art climate model or the real climate system. Using a global ocean model subject to freshwater forcing, we show that a collapse of the Atlantic Meridional Overturning Circulation can indeed be induced even by small-amplitude changes in the forcing, if the rate of change is fast enough. Identifying the location of critical thresholds in climate subsystems by slowly changing system parameters has been a core focus in assessing risks of abrupt climate change. This study suggests that such thresholds might not be relevant in practice, if parameter changes are not slow. Furthermore, we show that due to the chaotic dynamics of complex systems there is no well-defined critical rate of parameter change, which severely limits the predictability of the qualitative long-term behavior. The results show that the safe operating space of elements of the Earth system with respect to future emissions might be smaller than previously thought.

In touch with mental rotation: interactions between mental and tactile rotations and motor responses.

Although several process models have described the cognitive processing stages that are involved in mentally rotating objects, the exact nature of the rotation process itself remains elusive. According to embodied cognition, cognitive functions are deeply grounded in the sensorimotor system. We thus hypothesized that modal rotation perceptions should influence mental rotations. We conducted two studies in which participants had to judge if a rotated letter was visually presented canonically or mirrored. Concurrently, participants had to judge if a tactile rotation on their palm changed direction during the trial. The results show that tactile rotations can systematically influence mental rotation performance in that same rotations are favored. In addition, the results show that mental rotations produce a response compatibility effect: clockwise mental rotations facilitate responses to the right, while counterclockwise mental rotations facilitate responses to the left. We conclude that the execution of mental rotations activates cognitive mechanisms that are also used to perceive rotations in different modalities and that are associated with directional motor control processes.

Lost in space: multisensory conflict yields adaptation in spatial representations across frames of reference.

According to embodied cognition, bodily interactions with our environment shape the perception and representation of our body and the surrounding space, that is, peripersonal space. To investigate the adaptive nature of these spatial representations, we introduced a multisensory conflict between vision and proprioception in an immersive virtual reality. During individual bimanual interaction trials, we gradually shifted the visual hand representation. As a result, participants unknowingly shifted their actual hands to compensate for the visual shift. We then measured the adaptation to the invoked multisensory conflict by means of a self-localization and an external localization task. While effects of the conflict were observed in both tasks, the effects systematically interacted with the type of localization task and the available visual information while performing the localization task (i.e., the visibility of the virtual hands). The results imply that the localization of one's own hands is based on a multisensory integration process, which is modulated by the saliency of the currently most relevant sensory modality and the involved frame of reference. Moreover, the results suggest that our brain strives for consistency between its body and spatial estimates, thereby adapting multiple, related frames of reference, and the spatial estimates within, due to a sensory conflict in one of them.

Super-transient scaling in time-delay autonomous Boolean network motifs.

Autonomous Boolean networks are commonly used to model the dynamics of gene regulatory networks and allow for the prediction of stable dynamical attractors. However, most models do not account for time delays along the network links and noise, which are crucial features of real biological systems. Concentrating on two paradigmatic motifs, the toggle switch and the repressilator, we develop an experimental testbed that explicitly includes both inter-node time delays and noise using digital logic elements on field-programmable gate arrays. We observe transients that last millions to billions of characteristic time scales and scale exponentially with the amount of time delays between nodes, a phenomenon known as super-transient scaling. We develop a hybrid model that includes time delays along network links and allows for stochastic variation in the delays. Using this model, we explain the observed super-transient scaling of both motifs and recreate the experimentally measured transient distributions.

Virtual reality assessment of a high-calorie food bias: Replication and food-specificity in healthy participants.

BACKGROUND: Theoretical models and behavioural studies indicate faster approach behaviour for high-calorie food (approach bias) among healthy participants. A previous study with Virtual Reality (VR) and online motion-capture quantified this approach bias towards food and non-food cues in a controlled VR environment with hand movements. The aim of this study was to test the specificity of a manual approach bias for high-calorie food in grasp movements compared to low-calorie food and neutral objects of different complexity, namely, simple balls and geometrically more complex office tools. METHODS: In a VR setting, healthy participants (N = 27) repeatedly grasped or pushed high-calorie food, low-calorie food, balls and office tools in randomized order with 30 item repetitions. All objects were rated for valence and arousal. RESULTS: High-calorie food was less attractive and more arousing in subjective ratings than low-calorie food and neutral objects. Movement onset was faster for high-calorie food in push-trials, but overall push responses were comparable. In contrast, responses to high-calorie food relative to low-calorie food and to control objects were faster in grasp trials for later stages of interaction (grasp and collect). Non-parametric tests confirmed an approach bias for high-calorie food. CONCLUSION: A behavioural bias for food was specific to high-calorie food objects. The results confirm the presence of bottom-up advantages in motor-cognitive behaviour for high-calorie food in a non-clinical population. More systematic variations of object fidelity and in clinical populations are outstanding. The utility of VR in assessing approach behaviour is confirmed in this study by exploring manual interactions in a controlled environment.

Multistability and intermediate tipping of the Atlantic Ocean circulation.

Tipping points (TP) in climate subsystems are usually thought to occur at a well-defined, critical forcing parameter threshold, via destabilization of the system state by a single, dominant positive feedback. However, coupling to other subsystems, additional feedbacks, and spatial heterogeneity may promote further small-amplitude, abrupt reorganizations of geophysical flows at forcing levels lower than the critical threshold. Using a primitive-equation ocean model, we simulate a collapse of the Atlantic Meridional Overturning Circulation (AMOC) due to increasing glacial melt. Considerably before the collapse, various abrupt, qualitative changes in AMOC variability occur. These intermediate tipping points (ITP) are transitions between multiple stable circulation states. Using 2.75 million years of model simulations, we uncover a very rugged stability landscape featuring parameter regions of up to nine coexisting stable states. The path to an AMOC collapse via a sequence of ITPs depends on the rate of change of the meltwater input. This challenges our ability to predict and define safe limits for TPs.

Learning about others: Modeling social inference through ambiguity resolution.

Bayesian accounts of social cognition successfully model the human ability to infer goals and intentions of others on the basis of their behavior. In this paper, we extend this paradigm to the analysis of ambiguity resolution during brief communicative exchanges. In a reference game experimental setup, we observed that participants were able to infer listeners' preferences when analyzing their choice of object given referential ambiguity. Moreover, a subset of speakers was able to strategically choose ambiguous over unambiguous utterances in an epistemic manner, although a different group preferred unambiguous utterances. We show that a modified Rational Speech Act model well-approximates the data of both the inference of listeners' preferences and their utterance choices. In particular, the observed preference inference is modeled by Bayesian inference, which computes posteriors over hypothetical, behavior-influencing inner states of conversation partners-such as their knowledge, beliefs, intentions, or preferences-after observing their utterance-interpretation behavior. Utterance choice is modeled by anticipating social information gain, which we formalize as the expected knowledge change, when choosing a particular utterance and watching the listener's response. Taken together, our results demonstrate how social conversations allow us to (sometimes strategically) learn about each other when observing interpretations of ambiguous utterances.

Preserved Inhibitory Control Deficits of Overweight Participants in a Gamified Stop-Signal Task: Experimental Study of Validity.

BACKGROUND: Gamification in mental health could increase training adherence, motivation, and transfer effects, but the external validity of gamified tasks is unclear. This study documents that gamified task variants can show preserved associations between markers of behavioral deficits and health-related variables. We draw on the inhibitory control deficit in overweight populations to investigate effects of gamification on performance measures in a web-based experimental task. OBJECTIVE: This study tested whether associations between inhibitory control and overweight were preserved in a gamified stop-signal task (SST). METHODS: Two versions of an adaptive SST were developed and tested in an online experiment. Participants (n=111) were randomized to 1 of the 2 task variants and completed a series of questionnaires along with either the gamified SST or a conventional SST. To maximize its possible effects on participants' inhibitory control, the gamified SST included multiple game elements in addition to the task itself and the stimuli. Both variants drew on the identical core mechanics, but the gamified variant included an additional narrative, graphical theme, scoring system with visual and emotional feedback, and the presence of a companion character. In both tasks, food and neutral low-poly stimuli were classified based on their color tone (go trials), but responses were withheld in 25% of the trials (stop trials). Mean go reaction times and stop-signal reaction times (SSRT) were analyzed as measures of performance and inhibitory control. RESULTS: Participants in the gamified SST had longer reaction times (803 [SD 179] ms vs 607 [SD 90] ms) and worse inhibitory control (SSRT 383 [SD 109] ms vs 297 [SD 45] ms). The association of BMI with inhibitory control was relatively small (r=.155, 95% CI .013-.290). Overweight participants had longer reaction times (752 [SD 217] ms vs 672 [SD 137] ms) and SSRTs (363 [SD 116] ms vs 326 [SD 77] ms). Gamification did not interact with the effect of overweight on mean performance or inhibitory control. There were no effects of gamification on mood and user experience, despite a negative effect on perceived efficiency. CONCLUSIONS: The detrimental effects of heightened BMI on inhibitory control were preserved in a gamified version of the SST. Overall, the effects of overweight were smaller than in previously published web-based and laboratory studies. Gamification elements can impact behavioral performance, but gamified tasks can still assess inhibitory control deficits. Although our results are promising, according validations may differ for other types of behavior, gamification, and health variables.

Hands Ahead in Mind and Motion: Active Inference in Peripersonal Hand Space.

According to theories of anticipatory behavior control, actions are initiated by predicting their sensory outcomes. From the perspective of event-predictive cognition and active inference, predictive processes activate currently desired events and event boundaries, as well as the expected sensorimotor mappings necessary to realize them, dependent on the involved predicted uncertainties before actual motor control unfolds. Accordingly, we asked whether peripersonal hand space is remapped in an uncertainty anticipating manner while grasping and placing bottles in a virtual reality (VR) setup. To investigate, we combined the crossmodal congruency paradigm with virtual object interactions in two experiments. As expected, an anticipatory crossmodal congruency effect (aCCE) at the future finger position on the bottle was detected. Moreover, a manipulation of the visuo-motor mapping of the participants' virtual hand while approaching the bottle selectively reduced the aCCE at movement onset. Our results support theories of event-predictive, anticipatory behavior control and active inference, showing that expected uncertainties in movement control indeed influence anticipatory stimulus processing.

Mental space maps into the future.

It has been suggested that our mind anticipates the future to act in a goal-directed, event-oriented manner. Here we asked whether peripersonal hand space, that is, the space surrounding one's hands, is dynamically and adaptively mapped into the future while planning and executing a goal-directed object manipulation. We thus combined the crossmodal congruency paradigm (CCP), which has been used to study selective interactions between vision and touch within peripersonal space, with an object manipulation task. We expected crossmodal interactions in anticipation of the upcoming, currently planned object grasp, which varied trial-by-trial depending on the object's orientation. Our results confirm that visual distractors close to the future finger positions selectively influence vibrotactile perceptions. Moreover, vibrotactile stimulation influences gaze behavior in the light of the anticipated grasp. Both influences become apparent partly even before the hand starts to move, soon after visual target object onset. These results thus support theories of event encodings and anticipatory behavior, showing that peripersonal hand space is flexibly remapped onto a future, currently actively inferred hand position.

How Deep Is Your SNARC? Interactions Between Numerical Magnitude, Response Hands, and Reachability in Peripersonal Space.

Spatial, physical, and semantic magnitude dimensions can influence action decisions in human cognitive processing and interact with each other. For example, in the spatial-numerical associations of response code (SNARC) effect, semantic numerical magnitude facilitates left-hand or right-hand responding dependent on the small or large magnitude of number symbols. SNARC-like interactions of numerical magnitudes with the radial spatial dimension (depth) were postulated from early on. Usually, the SNARC effect in any direction is investigated using fronto-parallel computer monitors for presentation of stimuli. In such 2D setups, however, the metaphorical and literal interpretation of the radial depth axis with seemingly close/far stimuli or responses are not distinct. Hence, it is difficult to draw clear conclusions with respect to the contribution of different spatial mappings to the SNARC effect. In order to disentangle the different mappings in a natural way, we studied parametrical interactions between semantic numerical magnitude, horizontal directional responses, and perceptual distance by means of stereoscopic depth in an immersive virtual reality (VR). Two VR experiments show horizontal SNARC effects across all spatial displacements in traditional latency measures and kinematic response parameters. No indications of a SNARC effect along the depth axis, as it would be predicted by a direct mapping account, were observed, but the results show a non-linear relationship between horizontal SNARC slopes and physical distance. Steepest SNARC slopes were observed for digits presented close to the hands. We conclude that spatial-numerical processing is susceptible to effector-based processes but relatively resilient to task-irrelevant variations of radial-spatial magnitudes.

Transient dynamics and their control in time-delay autonomous Boolean ring networks.

Biochemical systems with switch-like interactions, such as gene regulatory networks, are well modeled by autonomous Boolean networks. Specifically, the topology and logic of gene interactions can be described by systems of continuous piecewise-linear differential equations, enabling analytical predictions of the dynamics of specific networks. However, most models do not account for time delays along links associated with spatial transport, mRNA transcription, and translation. To address this issue, we have developed an experimental test bed to realize a time-delay autonomous Boolean network with three inhibitory nodes, known as a repressilator, and use it to study the dynamics that arise as time delays along the links vary. We observe various nearly periodic oscillatory transient patterns with extremely long lifetime, which emerge in small network motifs due to the delay, and which are distinct from the eventual asymptotically stable periodic attractors. For repeated experiments with a given network, we find that stochastic processes give rise to a broad distribution of transient times with an exponential tail. In some cases, the transients are so long that it is doubtful the attractors will ever be approached in a biological system that has a finite lifetime. To counteract the long transients, we show experimentally that small, occasional perturbations applied to the time delays can force the trajectories to rapidly approach the attractors.

What determines the possession of assistive devices among patients with rheumatic diseases? The influence of the country-related health care system.

PURPOSE: To identify the determinants of the possession of assistive devices among patients with various rheumatic conditions. In order to determine the influence of the country-related health care system, patients from two different countries were studied. METHOD: Patients with rheumatoid arthritis (RA) or psoriatic arthritis (PsA) were selected from rheumatology outpatient clinics in two adjacent regions in The Netherlands and Germany. A total of 142 patients completed a self-administered questionnaire. Information on the possession of assistive devices and data on socio-demographics, clinical status and health status were obtained. Logistic regression analyses were used to identify determinants of the possession of assistive devices. RESULTS: The majority (78%) of the patients possessed at least one or more assistive devices. Obviously, functional status was the most important determinant, followed by the country where the patient resided. More assistive devices were found in increasingly disabled patients as well as in patients living in The Netherlands. CONCLUSION: Functional status and the patient's country are the most important determinants of the possession of assistive devices among patients with rheumatic conditions. We hypothesize that the most likely explanation for the differences in possession rates between countries are differences in societal systems for the prescription and reimbursement of assistive devices.

Behavioral Bias for Food Reflected in Hand Movements: A Preliminary Study with Healthy Subjects.

Palatable food induces general approach tendencies when compared to nonfood stimuli. For eating disorders, the modification of an attention bias toward food was proposed as a treatment option. Similar approaches have been efficient for other psychiatric conditions and, recently, successfully incorporated approach motivation. The direct impact of attentional biases on spontaneous natural behavior has hardly been investigated so far, although actions may serve as an intervention target, especially seeing the recent advances in the field of embodied cognition. In this study, we addressed the interplay of motor action execution and cognition when interacting with food objects. In a Virtual Reality (VR) setting, healthy participants repeatedly grasped or warded high-calorie food or hand-affordant ball objects using their own dominant hand. This novel experimental paradigm revealed an attention-like bias in hand-based actions: 3D objects of food were collected faster than ball objects, and this difference correlated positively with both individual body mass index and diet-related attitudes. The behavioral bias for food in hand movements complements several recent experimental and neurophysiological findings. Implications for the use of VR in the treatment of eating-related health problems are discussed.

Lessons on Climate Sensitivity From Past Climate Changes.

Over the last decade, our understanding of climate sensitivity has improved considerably. The climate system shows variability on many timescales, is subject to non-stationary forcing and it is most likely out of equilibrium with the changes in the radiative forcing. Slow and fast feedbacks complicate the interpretation of geological records as feedback strengths vary over time. In the geological past, the forcing timescales were different than at present, suggesting that the response may have behaved differently. Do these insights constrain the climate sensitivity relevant for the present day? In this paper, we review the progress made in theoretical understanding of climate sensitivity and on the estimation of climate sensitivity from proxy records. Particular focus lies on the background state dependence of feedback processes and on the impact of tipping points on the climate system. We suggest how to further use palaeo data to advance our understanding of the currently ongoing climate change.

The application of social impact bonds to universal health-care initiatives in South-East Asia.

Social impact bonds (SIBs) have the potential to improve the efficiency of government health-care spending in South-East Asia. In a SIB, governments sign a pay-for-performance contract with one or several providers of health-care services, and the providers borrow up-front capital from investors. Governments outside South-East Asia have started to experiment with SIBs in criminal justice, homelessness and health care. Governments of South-East Asia can advance the goal of universal health care by using SIBs to improve the efficiency of health-care service providers and by motivating providers to expand coverage. This paper describes SIBs and their potential application to health-care initiatives in the Region.

Balanced echo state networks.

This paper investigates the interaction between the driving output feedback and the internal reservoir dynamics in echo state networks (ESNs). The interplay is studied experimentally on the multiple superimposed oscillators (MSOs) benchmark. The experimental data reveals a dual effect of the output feedback strength on the network dynamics: it drives the dynamic reservoir but it can also block suitable reservoir dynamics. Moreover, the data shows that the reservoir size crucially co-determines the likelihood of generating an effective ESN. We show that dependent on the complexity of the MSO dynamics somewhat smaller networks can yield better performance. Optimizing the output feedback weight range and the network size is thus crucial for generating an effective ESN. With proper parameter choices, we show that it is possible to generate ESNs that approximate MSOs with several orders of magnitude smaller errors than those previously reported. We conclude that there appears to be still much more potential in ESNs than previously thought and sketch-out some promising future research directions.

Possession of assistive devices is related to improved psychological well-being in patients with rheumatic conditions.

OBJECTIVE: To investigate the relationship between the possession of assistive devices and psychological well-being in patients with rheumatic conditions. METHODS: Patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA) were selected from rheumatology outpatient clinics in 2 adjacent regions in The Netherlands and Germany. A total of 142 patients completed a questionnaire on the possession of assistive devices and psychological well-being. Questions on sociodemographics, clinical status, and health status were included. Hierarchical multiple linear regression analysis was used to determine the unique association between the number of assistive devices per patient and psychological well-being, controlling for confounding variables. RESULTS: Univariately, the number of assistive devices per patient was negatively associated with psychological well-being. Multivariately, the number of assistive devices per patient was positively associated with psychological well-being. Functional status was a negative confounder of the relationship between the possession of assistive devices and psychological well-being. CONCLUSIONl The possession of assistive devices was positively related to psychological well-being of patients with rheumatic diseases, after controlling for differences in functional status.