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Social Foraging
Dynamics of Social Interaction
Curated by Ashish Umre
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Killer whales are "mummy's boys" - Menopause, Ageing, Parental Care, and Mummy's Boys!

Killer whales are "mummy's boys" -  Menopause, Ageing, Parental Care, and Mummy's Boys! | Social Foraging | Scoop.it

An international team of scientists has found the answer to why female killer whales have the longest menopause of any non-human species - to care for their adult sons.


The research led by the Universities of York and Exeter and published in the journal Science, shows that, for a male over 30, the death of his mother means an almost 14-fold-increase in the likelihood of his death within the following year.

 

The reason for the menopause remains one of nature’s great mysteries and very few species have a prolonged period of their lifespan when they no longer reproduce, as in humans.

 

However, female killer whales stop reproducing in their 30s-40s, but can survive into their 90s. While different theories have been put forward for the evolution of menopause in humans, including the well-established ‘grandmother’ hypothesis, there has been no definitive answer to why females of a small number of other species, including killer whales, also stop reproducing part-way through their lives.

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Experience of action depends on intention, not body movement: An experiment on memory for mens rea

Experience of action depends on intention, not body movement: An experiment on memory for mens rea | Social Foraging | Scoop.it

How do we know whether our own actions were voluntary or involuntary? Intentional theories of sense of agency suggest that we consciously perceive the intentions that accompany our actions, but reconstructive theories suggest that we perceive our actions only through the body movements and other effects that they produce. Intentions would then be mere confabulations, and not bona fide experiences. Previous work on voluntary action has focused on immediate experiences of authorship, and few studies have considered memory for voluntary actions. We devised an experiment in which both voluntary action and involuntary movement always occurred at the same time, but could either involve the same hand (congruent condition), or different hands (incongruent condition). When signals from the voluntary and involuntary movements involved different hands, they could therefore potentially interfere in memory. We found that recall of a voluntary action was unaffected by an incongruent involuntary movement. In contrast, recall of an involuntary movement was strongly influenced by an incongruent voluntary action. Our results demonstrate an “intentional capture” of body movement by voluntary actions, in support of intentional theories of agency, but contrary to reconstructive theories. When asked to recall both actions and movements, people's responses are shaped by memory of what they intended to do, rather than by how their body moved.

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Quantitative Assessment of the Importance of Phenotypic Plasticity in Adaptation to Climate Change in Wild Bird Populations

Quantitative Assessment of the Importance of Phenotypic Plasticity in Adaptation to Climate Change in Wild Bird Populations | Social Foraging | Scoop.it

Predictions about the fate of species or populations under climate change scenarios typically neglect adaptive evolution and phenotypic plasticity, the two major mechanisms by which organisms can adapt to changing local conditions. As a consequence, we have little understanding of the scope for organisms to track changing environments by in situ adaptation. Here, we use a detailed individual-specific long-term population study of great tits (Parus major) breeding in Wytham Woods, Oxford, UK to parameterise a mechanistic model and thus directly estimate the rate of environmental change to which in situ adaptation is possible. Using the effect of changes in early spring temperature on temporal synchrony between birds and a critical food resource, we focus in particular on the contribution of phenotypic plasticity to population persistence. Despite using conservative estimates for evolutionary and reproductive potential, our results suggest little risk of population extinction under projected local temperature change; however, this conclusion relies heavily on the extent to which phenotypic plasticity tracks the changing environment. Extrapolating the model to a broad range of life histories in birds suggests that the importance of phenotypic plasticity for adjustment to projected rates of temperature change increases with slower life histories, owing to lower evolutionary potential. Understanding the determinants and constraints on phenotypic plasticity in natural populations is thus crucial for characterising the risks that rapidly changing environments pose for the persistence of such populations.

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9th Congress of the EUS-UES | Globalization and Crisis. Complexity and governance of systems – Valencia 2014

The 9th meeting of the European Union of Systems, without ignoring all and each one of the traditional fields of the implementation of the system theory, the system thinking, the system analysis, the system dynamics and other related fields, is intended to draw together all the researchers and professionals that are working around the world on the globalization phenomenon and its consequences, as well as its links with the current crisis. Therefore, a series is different symposiums organized by themes are planned, in which is intended to analyse different relevant factors of this great system of systems that is becoming the world in which we are living. Thus, the main aim of the systemic debate is being focused on the “World System” and its governance considering its complexity, and framing the discussion according to its social, economic, political, organisational, historic, demographic and cultural implications. All of this, without ignoring the methodological factors belonging to the system science.

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Robot evolution: Hod Lipson’s artificial organisms have already escaped from the virtual realm.

Robot evolution: Hod Lipson’s artificial organisms have already escaped from the virtual realm. | Social Foraging | Scoop.it

In a laboratory tucked away in a corner of the Cornell University campus, Hod Lipson’s robots are evolving. He has already produced a self-aware robot that is able to gather information about itself as it learns to walk. Like a Toy Story character, it sits in a cubby surrounded by other former laboratory stars. There’s a set of modular cubes, looking like a cross between children’s blocks and the model cartilage one might see at the orthopaedist’s – this particular contraption enjoyed the spotlight in 2005 as one of the world’s first self-replicating robots. And there are cubbies full of odd-shaped plastic sculptures, including some chess pieces that are products of the lab’s 3D printer.

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The role of hidden influentials in the diffusion of online information cascades

In a diversified context with multiple social networking sites, heterogeneous activity patterns and different user-user relations, the concept of ``information cascade'' is all but univocal. Despite the fact that such information cascades can be defined in different ways, it is important to check whether some of the observed patterns are common to diverse contagion processes that take place on modern social media. Here, we explore one type of information cascades, namely, those that are time-constrained, related to two kinds of socially-rooted topics on Twitter. Specifically, we show that in both cases cascades sizes distribute following a fat tailed distribution and that whether or not a cascade reaches system-wide proportions is mainly given by the presence of so-called hidden influentials. These latter nodes are not the hubs, which on the contrary, often act as firewalls for information spreading. Our results are important for a better understanding of the dynamics of complex contagion and, from a practical side, for the identification of efficient spreaders in viral phenomena.

 

The role of hidden influentials in the diffusion of online information cascades
Baños RA, Borge-Holthoefer J, Moreno Y
EPJ Data Science 2013, 2:6 (26 July 2013)

http://dx.doi.org/10.1140/epjds18


Via Complexity Digest
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The developmental dynamics of terrorist organizations

We identify robust statistical patterns in the frequency and severity of violent attacks by terrorist organizations as they grow and age. Using group-level static and dynamic analyses of terrorist events worldwide from 1968-2008 and a simulation model of organizational dynamics, we show that the production of violent events tends to accelerate with increasing size and experience. This coupling of frequency, experience and size arises from a fundamental positive feedback loop in which attacks lead to growth which leads to increased production of new attacks. In contrast, event severity is independent of both size and experience. Thus larger, more experienced organizations are more deadly because they attack more frequently, not because their attacks are more deadly, and large events are equally likely to come from large and small organizations. These results hold across political ideologies and time, suggesting that the frequency and severity of terrorism may be constrained by fundamental processes.

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Psychosis-Proneness and Neural Correlates of Self-Inhibition in Theory of Mind

Psychosis-Proneness and Neural Correlates of Self-Inhibition in Theory of Mind | Social Foraging | Scoop.it

Impaired Theory of Mind (ToM) has been repeatedly reported as a feature of psychotic disorders. ToM is crucial in social interactions and for the development of social behavior. It has been suggested that reasoning about the belief of others, requires inhibition of the self-perspective. We investigated the neural correlates of self-inhibition in nineteen low psychosis prone (PP) and eighteen high PP subjects presenting with subclinical features. High PP subjects have a more than tenfold increased risk of developing a schizophrenia-spectrum disorder. Brain activation was measured with functional Magnetic Resonance Imaging during a ToM task differentiating between self-perspective inhibition and belief reasoning. Furthermore, to test underlying inhibitory mechanisms, we included a stop-signal task. We predicted worse behavioral performance for high compared to low PP subjects on both tasks. Moreover, based on previous neuroimaging results, different activation patterns were expected in the inferior frontal gyrus (IFG) in high versus low PP subjects in self-perspective inhibition and simple response inhibition. Results showed increased activation in left IFG during self-perspective inhibition, but not during simple response inhibition, for high PP subjects as compared to low PP subjects. High and low PP subjects showed equal behavioral performance. The results suggest that at a neural level, high PP subjects need more resources for inhibiting the self-perspective, but not for simple motor response inhibition, to equal the performance of low PP subjects. This may reflect a compensatory mechanism, which may no longer be available for patients with schizophrenia-spectrum disorders resulting in ToM impairments.

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Faster Is More Different: Mean-Field Dynamics of Innovation Diffusion

Faster Is More Different: Mean-Field Dynamics of Innovation Diffusion | Social Foraging | Scoop.it

Based on a recent model of paradigm shifts by Bornholdt et al., we studied mean-field opinion dynamics in an infinite population where an infinite number of ideas compete simultaneously with their values publicly known. We found that a highly innovative society is not characterized by heavy concentration in highly valued ideas: Rather, ideas are more broadly distributed in a more innovative society with faster progress, provided that the rate of adoption is constant, which suggests a positive correlation between innovation and technological disparity. Furthermore, the distribution is generally skewed in such a way that the fraction of innovators is substantially smaller than has been believed in conventional innovation-diffusion theory based on normality. Thus, the typical adoption pattern is predicted to be asymmetric with slow saturation in the ideal situation, which is compared with empirical data sets.

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Bursty Communication Patterns Facilitate Spreading in a Threshold-Based Epidemic Dynamics

Bursty Communication Patterns Facilitate Spreading in a Threshold-Based Epidemic Dynamics | Social Foraging | Scoop.it

Records of social interactions provide us with new sources of data for understanding how interaction patterns affect collective dynamics. Such human activity patterns are often bursty, i.e., they consist of short periods of intense activity followed by long periods of silence. This burstiness has been shown to affect spreading phenomena; it accelerates epidemic spreading in some cases and slows it down in other cases. We investigate a model of history-dependent contagion. In our model, repeated interactions between susceptible and infected individuals in a short period of time is needed for a susceptible individual to contract infection. We carry out numerical simulations on real temporal network data to find that bursty activity patterns facilitate epidemic spreading in our model.

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A Machine Learning Method for the Prediction of Receptor Activation in the Simulation of Synapses

A Machine Learning Method for the Prediction of Receptor Activation in the Simulation of Synapses | Social Foraging | Scoop.it

Chemical synaptic transmission involves the release of a neurotransmitter that diffuses in the extracellular space and interacts with specific receptors located on the postsynaptic membrane. Computer simulation approaches provide fundamental tools for exploring various aspects of the synaptic transmission under different conditions. In particular, Monte Carlo methods can track the stochastic movements of neurotransmitter molecules and their interactions with other discrete molecules, the receptors. However, these methods are computationally expensive, even when used with simplified models, preventing their use in large-scale and multi-scale simulations of complex neuronal systems that may involve large numbers of synaptic connections. We have developed a machine-learning based method that can accurately predict relevant aspects of the behavior of synapses, such as the percentage of open synaptic receptors as a function of time since the release of the neurotransmitter, with considerably lower computational cost compared with the conventional Monte Carlo alternative. The method is designed to learn patterns and general principles from a corpus of previously generated Monte Carlo simulations of synapses covering a wide range of structural and functional characteristics. These patterns are later used as a predictive model of the behavior of synapses under different conditions without the need for additional computationally expensive Monte Carlo simulations. This is performed in five stages: data sampling, fold creation, machine learning, validation and curve fitting. The resulting procedure is accurate, automatic, and it is general enough to predict synapse behavior under experimental conditions that are different to the ones it has been trained on. Since our method efficiently reproduces the results that can be obtained with Monte Carlo simulations at a considerably lower computational cost, it is suitable for the simulation of high numbers of synapses and it is therefore an excellent tool for multi-scale simulations.

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Roles of NO Signaling in Long-Term Memory Formation in Visual Learning in an Insect

Roles of NO Signaling in Long-Term Memory Formation in Visual Learning in an Insect | Social Foraging | Scoop.it

Many insects exhibit excellent capability of visual learning, but the molecular and neural mechanisms are poorly understood. This is in contrast to accumulation of information on molecular and neural mechanisms of olfactory learning in insects. In olfactory learning in insects, it has been shown that cyclic AMP (cAMP) signaling critically participates in the formation of protein synthesis-dependent long-term memory (LTM) and, in some insects, nitric oxide (NO)-cyclic GMP (cGMP) signaling also plays roles in LTM formation. In this study, we examined the possible contribution of NO-cGMP signaling and cAMP signaling to LTM formation in visual pattern learning in crickets. Crickets that had been subjected to 8-trial conditioning to associate a visual pattern with water reward exhibited memory retention 1 day after conditioning, whereas those subjected to 4-trial conditioning exhibited 30-min memory retention but not 1-day retention. Injection of cycloheximide, a protein synthesis inhibitor, into the hemolymph prior to 8-trial conditioning blocked formation of 1-day memory, whereas it had no effect on 30-min memory formation, indicating that 1-day memory can be characterized as protein synthesis-dependent long-term memory (LTM). Injection of an inhibitor of the enzyme producing an NO or cAMP prior to 8-trial visual conditioning blocked LTM formation, whereas it had no effect on 30-min memory formation. Moreover, injection of an NO donor, cGMP analogue or cAMP analogue prior to 4-trial conditioning induced LTM. Induction of LTM by an NO donor was blocked by DDA, an inhibitor of adenylyl cyclase, an enzyme producing cAMP, but LTM induction by a cAMP analogue was not impaired by L-NAME, an inhibitor of NO synthase. The results indicate that cAMP signaling is downstream of NO signaling for visual LTM formation. We conclude that visual learning and olfactory learning share common biochemical cascades for LTM formation.

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Resting State Networks' Corticotopy: The Dual Intertwined Rings Architecture

Resting State Networks' Corticotopy: The Dual Intertwined Rings Architecture | Social Foraging | Scoop.it

How does the brain integrate multiple sources of information to support normal sensorimotor and cognitive functions? To investigate this question we present an overall brain architecture (called “the dual intertwined rings architecture”) that relates the functional specialization of cortical networks to their spatial distribution over the cerebral cortex (or “corticotopy”). Recent results suggest that the resting state networks (RSNs) are organized into two large families: 1) a sensorimotor family that includes visual, somatic, and auditory areas and 2) a large association family that comprises parietal, temporal, and frontal regions and also includes the default mode network. We used two large databases of resting state fMRI data, from which we extracted 32 robust RSNs. We estimated: (1) the RSN functional roles by using a projection of the results on task based networks (TBNs) as referenced in large databases of fMRI activation studies; and (2) relationship of the RSNs with the Brodmann Areas. In both classifications, the 32 RSNs are organized into a remarkable architecture of two intertwined rings per hemisphere and so four rings linked by homotopic connections. The first ring forms a continuous ensemble and includes visual, somatic, and auditory cortices, with interspersed bimodal cortices (auditory-visual, visual-somatic and auditory-somatic, abbreviated as VSA ring). The second ring integrates distant parietal, temporal and frontal regions (PTF ring) through a network of association fiber tracts which closes the ring anatomically and ensures a functional continuity within the ring. The PTF ring relates association cortices specialized in attention, language and working memory, to the networks involved in motivation and biological regulation and rhythms. This “dual intertwined architecture” suggests a dual integrative process: the VSA ring performs fast real-time multimodal integration of sensorimotor information whereas the PTF ring performs multi-temporal integration (i.e., relates past, present, and future representations at different temporal scales).

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Teaching kids about complex systems is valuable

Teaching kids about complex systems is valuable | Social Foraging | Scoop.it

It is amazing that in a world progressing so rapidly in technology, the U.S. supply of computer scientists should be in such a state of crisis. The National Bureau of Labor and Statistics estimates that there will be 1.5 million computer science jobs in the U.S. by 2018. Of those, we will be able to fill less than 30 percent with U.S. graduates. We, as a nation, are not producing enough computer scientists to meet the current demands in our country’s job market, much less its future demands. And, unlike other areas of science and engineering, the number of computer science graduates is not increasing yearly to help us meet this demand.

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Mimicking human neuronal pathways in silico: an emergent model on the effective connectivity

Mimicking human neuronal pathways in silico: an emergent model on the effective connectivity | Social Foraging | Scoop.it

We present a novel computational model that detects temporal configurations of a given human neuronal pathway and constructs its artificial replication. This poses a great challenge since direct recordings from individual neurons are impossible in the human central nervous system and therefore the underlying neuronal pathway has to be considered as a black box. For tackling this challenge, we used a branch of complex systems modeling called artificial self-organization in which large sets of software entities interacting locally give rise to bottom-up collective behaviors. The result is an emergent model where each software entity represents an integrate-and-fire neuron. We then applied the model to the reflex responses of single motor units obtained from conscious human subjects. Experimental results show that the model recovers functionality of real human neuronal pathways by comparing it to appropriate surrogate data. What makes the model promising is the fact that, to the best of our knowledge, it is the first realistic model to self-wire an artificial neuronal network by efficiently combining neuroscience with artificial self-organization. Although there is no evidence yet of the model’s connectivity mapping onto the human connectivity, we anticipate this model will help neuroscientists to learn much more about human neuronal networks, and could also be used for predicting hypotheses to lead future experiments.

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Bian Wu's curator insight, October 12, 2014 9:41 PM

close to my project

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XKeyscore presentation from 2008 – read in full

XKeyscore presentation from 2008 – read in full | Social Foraging | Scoop.it

Training materials for the XKeyscore program detail how analysts can use it and other systems to mine enormous agency databases and develop intelligence from the web.

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The Real Reason Kids Need to Master Their Math Skills

The Real Reason Kids Need to Master Their Math Skills | Social Foraging | Scoop.it

In Teaching Other People’s Children, Lisa Delpit writes: “Skills are a necessary but insufficient aspect of black and minority students’ education. Students need technical skills to open doors, but they need to be able to think critically and creatively to participate in meaningful and potentially liberating work inside those doors.”

 

Answering a math problem these days, no matter how accurate or fast, does not provide anyone with a particular advantage in life. The reality is that calculators and computers can out-compute a human being when it comes to finding an answer.

 

The advantage is created when a person develops, intuitively or through training, the ability to apply the thinking, patterns, and ideas behind the math to help them or others make better sense of our world.

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Neuroscience & Philosophy: An Exchange by Jean-Pierre Changeux

Neuroscience & Philosophy: An Exchange by Jean-Pierre Changeux | Social Foraging | Scoop.it

In my response to Colin McGinn [“What Can Your Neurons Tell You?,” NYR, July 11] I don’t wish to enter into the philosophical debate between philosophers and neuroscientists. Even if it is much needed, it requires extensive developments that are being carried out in different circles. I shall be concerned here by facts as they are reported in his NYR review.

 

First of all I am shocked by the overall arrogant style of his review. The use of the attributes “fallacy” or “confusion,” if still employed by some philosophers, does not belong to a dialogue between a scientist and a philosopher. Differences of opinion or of interpretation are more acceptable terms. Time has passed since Auguste Comte’s suggested hierarchy of disciplines. There is no reason today for philosophers to give “lessons” to anybody, scientists in particular. McGinn might read Bourdieu’s book on “distinction” to question his attitude. I see the relation between neuroscientists and philosophers in a much more positive and constructive manner, as a fruitful cooperation to understand, jointly, the “mind-brain” and to evaluate the consequences of the constantly progressing field of neuroscience—from the molecular to the cognitive level—on both theoretical and practical aspects of human productions. There are at present quite a number of philosophers like John Searle, Daniel Dennett, or Ned Block who play this role.

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foc.us Transcranial Direct Current Stimulation Headset Helps Get Your Game On

foc.us Transcranial Direct Current Stimulation Headset Helps Get Your Game On | Social Foraging | Scoop.it

Video gaming is primarily a sport of the brain, so to exercise this "muscle" it you need specialty equipment. Electric neurostimulators have been used for years in therapy and as an adjunct to exercise, but now a new device lets you use transcranial Direct Current Stimulation (tDCS) to “increase the plasticity of your brain,” according to Focus Labs, the company that makes it. It’s mostly geared toward video gamers that want to improve their hand-eye coordination and get an edge on opponents, but if the system really does improve individual performance, perhaps one day we’ll see it used by clinical specialists like surgeons and trauma docs during procedures to improve focus and prevent mistakes. It’s controlled via Bluetooth through an iOS device like an iPad or iPhone, and you can set the strength of the current and duration for your particular needs. Now, no playing One Flew Over the Cuckoo’s Nest at home, even if you can figure out how to hook up more power to the thing.

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Environmental structure and competitive scoring advantages in team competitions

In most professional sports, the structure of the environment is kept neutral so that scoring imbalances may be attributed to differences in team skill. It thus remains unknown what impact structural heterogeneities can have on scoring dynamics and producing competitive advantages. Applying a generative model of scoring dynamics to roughly 10 million team competitions drawn from an online game, we quantify the relationship between a competition's structure and its scoring dynamics. Despite wide structural variations, we find the same three-phase pattern in the tempo of events observed in many sports. Tempo and balance are highly predictable from a competition's structural features alone and teams exploit environmental heterogeneities for sustained competitive advantage. The most balanced competitions are associated with specific environmental heterogeneities, not from equally skilled teams. These results shed new light on the principles of balanced competition, and illustrate the potential of online game data for investigating social dynamics and competition.

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Spatial Structures of the Environment and of Dispersal Impact Species Distribution in Competitive Metacommunities

Spatial Structures of the Environment and of Dispersal Impact Species Distribution in Competitive Metacommunities | Social Foraging | Scoop.it

The correspondence between species distribution and the environment depends on species’ ability to track favorable environmental conditions (via dispersal) and to maintain competitive hierarchy against the constant influx of migrants (mass effect) and demographic stochasticity (ecological drift). Here we report a simulation study of the influence of landscape structure on species distribution. We consider lottery competition for space in a spatially heterogeneous environment, where the landscape is represented as a network of localities connected by dispersal. We quantified the contribution of neutrality and species sorting to their spatial distribution. We found that neutrality increases and the strength of species-sorting decreases with the centrality of a community in the landscape when the average dispersal among communities is low, whereas the opposite was found at elevated dispersal. We also found that the strength of species-sorting increases with environmental heterogeneity. Our results illustrate that spatial structure of the environment and of dispersal must be taken into account for understanding species distribution. We stress the importance of spatial geographic structure on the relative importance of niche vs. neutral processes in controlling community dynamics.

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Information and Perception of Meaningful Patterns

Information and Perception of Meaningful Patterns | Social Foraging | Scoop.it

The visual system needs to extract the most important elements of the external world from a large flux of information in a short time for survival purposes. It is widely believed that in performing this task, it operates a strong data reduction at an early stage, by creating a compact summary of relevant information that can be handled by further levels of processing. In this work we formulate a model of early vision based on a pattern-filtering architecture, partly inspired by high-speed digital data reduction in experimental high-energy physics (HEP). This allows a much stronger data reduction than models based just on redundancy reduction. We show that optimizing this model for best information preservation under tight constraints on computational resources yields surprisingly specific a-priori predictions for the shape of biologically plausible features, and for experimental observations on fast extraction of salient visual features by human observers. Interestingly, applying the same optimized model to HEP data acquisition systems based on pattern-filtering architectures leads to specific a-priori predictions for the relevant data patterns that these devices extract from their inputs. These results suggest that the limitedness of computing resources can play an important role in shaping the nature of perception, by determining what is perceived as “meaningful features” in the input data.

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Michael Rost's comment, August 19, 2013 10:03 AM
Listening is in part 'data reduction', taking an overly rich and complex input source and creating meaning from it...
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Do Bodily Expressions Compete with Facial Expressions? Time Course of Integration of Emotional Signals from the Face and the Body

Do Bodily Expressions Compete with Facial Expressions? Time Course of Integration of Emotional Signals from the Face and the Body | Social Foraging | Scoop.it

The decoding of social signals from nonverbal cues plays a vital role in the social interactions of socially gregarious animals such as humans. Because nonverbal emotional signals from the face and body are normally seen together, it is important to investigate the mechanism underlying the integration of emotional signals from these two sources. We conducted a study in which the time course of the integration of facial and bodily expressions was examined via analysis of event-related potentials (ERPs) while the focus of attention was manipulated. Distinctive integrating features were found during multiple stages of processing. In the first stage, threatening information from the body was extracted automatically and rapidly, as evidenced by enhanced P1 amplitudes when the subjects viewed compound face-body images with fearful bodies compared with happy bodies. In the second stage, incongruency between emotional information from the face and the body was detected and captured by N2. Incongruent compound images elicited larger N2s than did congruent compound images. The focus of attention modulated the third stage of integration. When the subjects' attention was focused on the face, images with congruent emotional signals elicited larger P3s than did images with incongruent signals, suggesting more sustained attention and elaboration of congruent emotional information extracted from the face and body. On the other hand, when the subjects' attention was focused on the body, images with fearful bodies elicited larger P3s than did images with happy bodies, indicating more sustained attention and elaboration of threatening information from the body during evaluative processes.

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Has Large-Scale Named-Entity Network Analysis Been Resting on a Flawed Assumption?

Has Large-Scale Named-Entity Network Analysis Been Resting on a Flawed Assumption? | Social Foraging | Scoop.it

The assumption that a name uniquely identifies an entity introduces two types of errors: splitting treats one entity as two or more (because of name variants); lumping treats multiple entities as if they were one (because of shared names). Here we investigate the extent to which splitting and lumping affect commonly-used measures of large-scale named-entity networks within two disambiguated bibliographic datasets: one for co-author names in biomedicine (PubMed, 2003–2007); the other for co-inventor names in U.S. patents (USPTO, 2003–2007). In both cases, we find that splitting has relatively little effect, whereas lumping has a dramatic effect on network measures. For example, in the biomedical co-authorship network, lumping (based on last name and both initials) drives several measures down: the global clustering coefficient by a factor of 4 (from 0.265 to 0.066); degree assortativity by a factor of ~13 (from 0.763 to 0.06); and average shortest path by a factor of 1.3 (from 5.9 to 4.5). These results can be explained in part by the fact that lumping artificially creates many intransitive relationships and high-degree vertices. This effect of lumping is much less dramatic but persists with measures that give less weight to high-degree vertices, such as the mean local clustering coefficient and log-based degree assortativity. Furthermore, the log-log distribution of collaborator counts follows a much straighter line (power law) with splitting and lumping errors than without, particularly at the low and the high counts. This suggests that part of the power law often observed for collaborator counts in science and technology reflects an artifact: name ambiguity.

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The Collaborative Image of The City: Mapping the Inequality of Urban Perception

The Collaborative Image of The City: Mapping the Inequality of Urban Perception | Social Foraging | Scoop.it

A traveler visiting Rio, Manila or Caracas does not need a report to learn that these cities are unequal; she can see it directly from the taxicab window. This is because in most cities inequality is conspicuous, but also, because cities express different forms of inequality that are evident to casual observers. Cities are highly heterogeneous and often unequal with respect to the income of their residents, but also with respect to the cleanliness of their neighborhoods, the beauty of their architecture, and the liveliness of their streets, among many other evaluative dimensions. Until now, however, our ability to understand the effect of a city's built environment on social and economic outcomes has been limited by the lack of quantitative data on urban perception. Here, we build on the intuition that inequality is partly conspicuous to create quantitative measure of a city's contrasts. Using thousands of geo-tagged images, we measure the perception of safety, class and uniqueness; in the cities of Boston and New York in the United States, and Linz and Salzburg in Austria, finding that the range of perceptions elicited by the images of New York and Boston is larger than the range of perceptions elicited by images from Linz and Salzburg. We interpret this as evidence that the cityscapes of Boston and New York are more contrasting, or unequal, than those of Linz and Salzburg. Finally, we validate our measures by exploring the connection between them and homicides, finding a significant correlation between the perceptions of safety and class and the number of homicides in a NYC zip code, after controlling for the effects of income, population, area and age. Our results show that online images can be used to create reproducible quantitative measures of urban perception and characterize the inequality of different cities.

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