Simulating emergence of novelties using agent-based models.

Understanding the growth and evolution of social networks is an important area of study, as these networks form the foundation for many popular online services such as social networking sites (SNS) and online games. However, previous models developed to explain the growth mechanisms of these networks have struggled to accurately reproduce certain behaviors that are frequently observed in real data, such as waves of novelty, in which new individuals or topics receive more attention than existing ones for a short period of time. In this study, we introduce a new model that incorporates context information into existing agent-based models in order to more accurately capture the structure and growth dynamics of these networks. Context information is introduced through labels based on the timing of appearance and relationships with antecedent agents. New agents are first added to the network when they are called by existing agents, and at this time they are also given a label. Agents added to the network at the same time by the same agent will have the same label. These labels are used to classify agents and give them different selection probabilities. This newly introduced selection probability creates a mechanism in which new agents receive attention beyond preferential attachment. By comparing the results of our model with real data on ten metrics, we demonstrate that it is able to produce behavior that more closely resembles real data. This improved understanding of the dynamics of social networks has important implications for designing effective interventions, including strategies for user acquisition and retention.

Analysis and Design of Social Presence in a Computer-Mediated Communication System.

Social presence, or the subjective experience of being present with another existing person, varies with the interaction medium. In general, social presence research has mainly focused on uni-directional aspects of each exchanged message, not on bidirectional interactions. Our primary purpose is to introduce such bidirectional evaluation by quantifying the degree of social presence with a few statistical measures. To this end, we developed a software called "TypeTrace" that records all keystrokes of online chat interactants and reenacts their typing actions and analyzed the results from different chat conditions, mainly focusing on the characterization of bi-directional interactions. We also compared the chat interaction patterns with the patterns from phone call datasets to investigate the difference of live communication in different media. The hypothesis of the experiment was that either richness or concurrency of communication is important for organizing social presence. Richness is defined by the variety of information at a time in communication and the concurrency is the number of temporal thread being processed at the same time. Our results show that when we merely increase the richness of information by presenting the typing process, the cognition of others' presence does not significantly increase. However, when the information concurrency is augmented by introducing the transmission of realtime text, we found that the transfer entropy between the interactants becomes considerably higher, and the social presence and emotional arousal, intimacy increased. High transfer entropy was also observed in the phone call dataset. This result shows that the mere augmentation of information richness does not necessarily lead to increased social presence, and concurrent communication is another critical factor for fostering vivid conversation in digital environments.

Open-Ended Evolution and a Mechanism of Novelties in Web Services.

Web services are analogous to living ecosystems in nature, in that they form an artificial ecosystem consisting of many tags and their associated media, such as photographs, movies, and web pages created by human users. In biological ecosystems, we view a tag as a species and a human as a hidden environmental resource. Our study examines the evolution of web services, in particular social tagging systems, with respect to the self-organization of new tags. The evolution of new combinations of tags is analyzed as an open-ended evolution (OEE) index. Tag meaning is computed by types of associated tags, including tags that vary their meanings temporally, which, we argue, are examples of OEE.

A Sensorimotor Signature of the Transition to Conscious Social Perception: Co-regulation of Active and Passive Touch.

It is not yet well understood how we become conscious of the presence of other people as being other subjects in their own right. Developmental and phenomenological approaches are converging on a relational hypothesis: my perception of a "you" is primarily constituted by another subject's attention being directed toward "me." This is particularly the case when my body is being physically explored in an intentional manner. We set out to characterize the sensorimotor signature of the transition to being aware of the other by re-analyzing time series of embodied interactions between pairs of adults (recorded during a "perceptual crossing" experiment). Measures of turn-taking and movement synchrony were used to quantify social coordination, and transfer entropy was used to quantify direction of influence. We found that the transition leading to one's conscious perception of the other's presence was indeed characterized by a significant increase in one's passive reception of the other's tactile stimulations. Unexpectedly, one's clear experience of such passive touch was consistently followed by a switch to active touching of the other, while the other correspondingly became more passive, which suggests that this intersubjective experience was reciprocally co-regulated by both participants.

Life as an emergent phenomenon: studies from a large-scale boid simulation and web data.

A large group with a special structure can become the mother of emergence. We discuss this hypothesis in relation to large-scale boid simulations and web data. In the boid swarm simulations, the nucleation, organization and collapse dynamics were found to be more diverse in larger flocks than in smaller flocks. In the second analysis, large web data, consisting of shared photos with descriptive tags, tended to group together users with similar tendencies, allowing the network to develop a core-periphery structure. We show that the generation rate of novel tags and their usage frequencies are high in the higher-order cliques. In this case, novelty is not considered to arise randomly; rather, it is generated as a result of a large and structured network. We contextualize these results in terms of adjacent possible theory and as a new way to understand collective intelligence. We argue that excessive information and material flow can become a source of innovation.This article is part of the themed issue 'Reconceptualizing the origins of life'.

WebAL Comes of Age: A Review of the First 21 Years of Artificial Life on the Web.

We present a survey of the first 21 years of web-based artificial life (WebAL) research and applications, broadly construed to include the many different ways in which artificial life and web technologies might intersect. Our survey covers the period from 1994-when the first WebAL work appeared-up to the present day, together with a brief discussion of relevant precursors. We examine recent projects, from 2010-2015, in greater detail in order to highlight the current state of the art. We follow the survey with a discussion of common themes and methodologies that can be observed in recent work and identify a number of likely directions for future work in this exciting area.

Predicting the neural effect of switching from donepezil to galantamine based on single-photon emission computed tomography findings in patients with Alzheimer's disease.

BACKGROUND: A number of neuroimaging studies have addressed the specific effect of treatment with cholinesterase inhibitors on the frontal lobe in patients with Alzheimer's disease (AD). However, the neural effects of cholinesterase inhibitors on both apathy and executive dysfunction remain unclear. We examined whether baseline regional cerebral blood flow, as determined by using single-photon emission computed tomography, is capable of predicting changes in apathy and executive dysfunction in response to AD patients switching from donepezil to galantamine therapy. METHODS: We conducted a 24-week, prospective, open-label study of AD patients treated with galantamine who did not respond to previous treatment with donepezil. Single-photon emission computed tomography was performed at baseline, and behaviour and cognitive assessments including the Mini-Mental State Examination, the Japanese version of the Alzheimer's Disease Assessment Scale-cognitive subscale, the Frontal Assessment Battery, the Neuropsychiatry Inventory Brief Questionnaire Form, and the Dysexecutive Questionnaire were conducted at three time points (baseline and after 12 and 24 weeks of galantamine therapy). RESULTS: After galantamine therapy, the Neuropsychiatry Inventory Brief Questionnaire Form scores (apathy, irritability, and aberrant motor symptoms) and the Dysexecutive Questionnaire score improved significantly. The single-photon emission computed tomography findings showed that lower baseline regional cerebral blood flow values in several frontal areas, including the dorsolateral and ventrolateral prefrontal cortex, the anterior cingulate, and the orbitofrontal cortex, predicted greater reductions in the score for apathy (distress) on the Neuropsychiatry Inventory Brief Questionnaire Form and the Dysexecutive Questionnaire score after patients switched from donepezil to galantamine therapy. CONCLUSIONS: Our study suggests that galantamine therapy, unlike donepezil, is characterized by a dual mechanism of action that may increase acetylcholine and the nicotinic receptor-modulation effect within the frontal lobe, both of which are associated with apathy and executive dysfunction in AD patients.

Self-organization on social media: endo-exo bursts and baseline fluctuations.

A salient dynamic property of social media is bursting behavior. In this paper, we study bursting behavior in terms of the temporal relation between a preceding baseline fluctuation and the successive burst response using a frequency time series of 3,000 keywords on Twitter. We found that there is a fluctuation threshold up to which the burst size increases as the fluctuation increases and that above the threshold, there appears a variety of burst sizes. We call this threshold the critical threshold. Investigating this threshold in relation to endogenous bursts and exogenous bursts based on peak ratio and burst size reveals that the bursts below this threshold are endogenously caused and above this threshold, exogenous bursts emerge. Analysis of the 3,000 keywords shows that all the nouns have both endogenous and exogenous origins of bursts and that each keyword has a critical threshold in the baseline fluctuation value to distinguish between the two. Having a threshold for an input value for activating the system implies that Twitter is an excitable medium. These findings are useful for characterizing how excitable a keyword is on Twitter and could be used, for example, to predict the response to particular information on social media.

Exploring default mode and information flow on the web.

Social networking services (e.g., Twitter, Facebook) are now major sources of World Wide Web (called "Web") dynamics, together with Web search services (e.g., Google). These two types of Web services mutually influence each other but generate different dynamics. In this paper, we distinguish two modes of Web dynamics: the reactive mode and the default mode. It is assumed that Twitter messages (called "tweets") and Google search queries react to significant social movements and events, but they also demonstrate signs of becoming self-activated, thereby forming a baseline Web activity. We define the former as the reactive mode and the latter as the default mode of the Web. In this paper, we investigate these reactive and default modes of the Web's dynamics using transfer entropy (TE). The amount of information transferred between a time series of 1,000 frequent keywords in Twitter and the same keywords in Google queries is investigated across an 11-month time period. Study of the information flow on Google and Twitter revealed that information is generally transferred from Twitter to Google, indicating that Twitter time series have some preceding information about Google time series. We also studied the information flow among different Twitter keywords time series by taking keywords as nodes and flow directions as edges of a network. An analysis of this network revealed that frequent keywords tend to become an information source and infrequent keywords tend to become sink for other keywords. Based on these findings, we hypothesize that frequent keywords form the Web's default mode, which becomes an information source for infrequent keywords that generally form the Web's reactive mode. We also found that the Web consists of different time resolutions with respect to TE among Twitter keywords, which will be another focal point of this paper.

Behavior management approach for agitated behavior in Japanese patients with dementia: a pilot study.

BACKGROUND: Agitated behaviors are frequently observed in patients with dementia and can cause severe distress to caregivers. However, little evidence of the efficacy of nonpharmacological interventions for agitated behaviors exists for patients with dementia. The present pilot study aimed to evaluate a behavioral management program developed by the Seattle Protocols for patients with agitated behaviors in Japan. METHODS: Eighteen patients with dementia (Alzheimer's disease, n = 14; dementia with Lewy bodies, n = 4) participated in an open study testing the effectiveness of a behavioral management program. The intervention consisted of 20 sessions over the course of 3 months. The primary outcomes were severity of agitation in dementia, as measured using the Agitated Behavior in Dementia scale (ABID) and the Cohen-Mansfield Agitation Inventory (CMAI). RESULTS: The behavioral management program resulted in significant reductions in total scores on both the ABID and CMAI. Although both physically agitated and verbally agitated behavior scores on the ABID improved significantly, symptoms of psychosis did not improve after the intervention. CONCLUSION: The behavioral management technique may be beneficial to distressed caregivers of patients with dementia. In the future, a well designed study to develop the behavioral management program more fully is needed.

Neuroanatomical abnormalities before onset of delusions in patients with Alzheimer's disease: a voxel-based morphometry study.

BACKGROUND: Structural brain abnormalities associated with delusions in Alzheimer's disease are poorly understood. In addition, whether the neural substrate underlying the delusions develops before the onset of the delusions is unclear. In this study, we used a voxel-based morphometry approach to examine the existence of regional structural abnormalities at baseline in patients with Alzheimer's disease who did and who did not develop delusions. METHODS: Using the Neuropsychiatric Inventory, we identified patients with Alzheimer's disease who exhibited delusions during a 2-year period. All the patients had undergone a magnetic resonance imaging examination at the start of the study period (baseline). We conducted a voxel-based morphometry analysis using statistical parametric mapping (SPM5) software and compared the results of patients with Alzheimer's disease who did and did not develop delusions. RESULTS: Compared with the patients who did not develop delusions (n = 35), the patients who did develop delusions (n = 18) had significantly smaller gray matter volumes on both sides of the parahippocampal gyrus, the right posterior cingulate gyrus, the right orbitofrontal cortex, both sides of the inferior frontal cortex, the right anterior cingulate, and the left insula. CONCLUSION: Structural brain abnormalities involving both the frontal and medial temporal lobes may be crucial to the expression of delusions in patients with Alzheimer's disease.

Decreased white matter integrity before the onset of delusions in patients with Alzheimer's disease: diffusion tensor imaging.

BACKGROUND: The pathology of delusions in patients with Alzheimer's disease (AD) associated with white matter (WM) abnormalities is poorly understood. In addition, whether the abnormalities in WM integrity that underlie the delusions develop before the onset of the delusions remains unclear. In this study, we used a diffusion tensor imaging approach to examine the existence of baseline abnormalities in WM integrity in AD patients who developed delusions and AD patients who did not develop delusions. METHODS: Using the Neuropsychiatric Inventory, we identified patients with AD who exhibit delusions during a 1-year period. All the patients underwent a magnetic resonance imaging (MRI) examination at baseline. We conducted fractional anisotropy using tract-based spatial statistics software and compared the results of AD patients who developed delusions with those who did not develop delusions. RESULTS: Compared with the AD patients who did not develop delusions (n = 15), the AD patients who developed delusions (n = 10) exhibited two relatively large clusters and one minimal cluster of significantly lower fractional anisotropy results. The first cluster was located in the left parieto-occipital region and included several fibers: the left inferior longitudinal fasciculus, the inferior fronto-occipital fasciculus, the posterior corona radiate, and the forceps major of the corpus callosum. The second cluster was located on the body of the corpus callosum. A third minimal cluster was located on the superior temporal gyrus white matter. CONCLUSION: Abnormalities in WM integrity involving several fibers may be crucial to the development of delusions in AD patients.