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.Comment: Presented at WebAL-1: Workshop on Artificial Life and the Web 2014 (arXiv:1406.2507

ソーシャルメディアにおけるバースト現象の理解と予測に関する研究

科学研究費助成事業 研究成果報告書：基盤研究(C)2015-2017課題番号 : 15K0042

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

Regional characteristics of diurnal variation of localized heavy rainfall frequency in Tokyo and its surroundings

The present study aimed to clarify the regional characteristics of the diurnal variation of localized heavy rainfall frequency in the Tokyo metropolitan area and Saitama Prefecture based on the dense hourly rainfall data acquired from 290 stations across summers of 15 years between 1994–2010 (June to September). The obtained results can be summarized as follows. The central to western parts of Saitama Prefecture (Cluster 2) displayed a single peak with a large maximum from the evening till the early night hours. In comparison, the western and southern parts of the Tama region (Cluster 4) and the western Tokyo area (Cluster 5) indicated a bimodal pattern with two peaks during the day and night. Moreover, central Tokyo, the northern Tama region, and southeastern Saitama Prefecture (Cluster 3) are located between these areas and can be considered a transition zone between the single-peak and bimodal areas. Despite the moderate increase in the frequency of heavy rainfall from evening to night in the eastern part of the Tokyo metropolitan area as well as the Saitama Prefecture (Cluster 1), it did not exhibit a clear maximum

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