Abstract: Novelties are part of our daily lives. We constantly adopt new technologies, conceive new ideas, meet new people, experiment with new situations. At different scales, innovation is also a crucial feature of many biological, technological and social systems. Recently, large databases witnessing human activities allowed the observation that novelties - such as the individual process of listening to a song for the first time - and innovation processes - such as the fixation of new genes in a population of bacteria - share striking statistical regularities. I will present a new framework based on Polya's urn to effectively model the emergence of the new and its regularities. What seems to be key in the successful modelling schemes proposed so far is the idea of looking at evolution as a path in a complex space, physical, conceptual, biological, technological, whose structure and topology get continuously reshaped and expanded by the occurrence of the new. This will be identified as a process of expansion into the adjacent possible, a concept originally introduced by Stuart Kauffmann in the framework of biological evolution. We will identify statistical signatures of the presence of the expansion into the adjacent possible in the analyzed datasets, and we will show that our modeling scheme is able to predict remarkably well these observations. References: F. Tria, V. Loreto, V.D.P. Servedio, S.H. Strogatz, Scientific Reports 4 (2014) V. Loreto, V.D.P. Servedio, S.H. Strogatz, F. Tria, in "Universality and Creativity in Language", E. Altmann, M. Degli Esposti and F. Pachet (eds.) Lecture Notes in Morphogenesis, (Springer) (2015)

Abstract: The simultaneous occurrence of events known as synchronization constitutes one of the most ubiquitous and fascinating phenomenon in complex systems. Synchronization has been observed in environments of different nature from power grids to biological and chemical systems. Despite the numerous studies on coupled oscillators on complex networks, all previous literature is based on the hypothesis that the synchronization process is costless and it thus does not require any investment by interacting oscillators. We study the evolution of cooperation and of synchronization on networks of coupled Kuramoto oscillators when the synchronization process is costly and when oscillators are able to avoid it. The introduction of costly synchronization leads to the formulation of a dichotomous scenario. In this framework, an oscillator may decide to pay the cost necessary to get synchronized, i.e. cooperating, or to simply wait others get synchronized with her frequency, i.e. defecting. The emergence of synchronization may thus be seen as the byproduct of an evolutionary Prisoner's Dilemma game in which oscillators can decide which behavior they adopt according to the payoff, i.e. the level of achieved synchronization, they receive in the previous round. We show how topology is essential in order for cooperation and consequent synchronization to thrive. We also display how different classes of topology foster differently synchronization both at a mascroscopic and microscopic level. The Kuramoto's Dilemma model – apart from looking at synchronization under a different perspective – can be helpful to study a wider range of social phenomena (such as motorial coordination, opinion dynamics and social rituals) in which synchronization and cooperation processes are both present and permanently coevolve.

Abstract: A large number of collective behaviors observed in animal and human groups, such as collective motion or collective decision, results from purely local interactions between neighboring individuals. However, the number and position of neighbors that influence the behavior of a focal individual may deeply affect the resulting collective dynamics. Here we design an experimental setup for human groups which allows to investigate the effect of influential neighbors on collective dynamics in a simple segregation task. We conduct a series of experiments where 22 pedestrians placed in a 7m diameter circular arena are asked to walk until an individual objective is reached. Pedestrians are informed that they are assigned one of two colors but ignore their own color and the color of the others. Pedestrians are then asked to walk simultaneously and find a place among the others so that their individual environment consists mostly of people of their own color. To do that, pedestrians hold electronic devices (Ubisense tags) that track their instantaneous position (2 Hz frequency) and emit an acoustic signal if the majority of their k nearest neighbors belongs to the other group. This setup allow us to precisely control in real time the number of k influential neighbors and the amount of information each individual can use to make a decision. We find that, after a transient time, pedestrians reach a stationary state where they are segregated in two or more clusters of one color, and this, for k odd from 1 to 13. Moreover, we find that an optimal number of influential neighbors k* exist which yields the fastest segregation process. This optimal segregation time is reached when pedestrians take into account their k*=9 closest neighbors; below this value, there is a lack of information, while above k*, an information overload effect takes place.

Abstract: As seen in musical ensembles, dance and conversation, people cooperatively produce various rhythmic patterns through real-time mutual interaction. The emergence of such rhythmic patterns is of great interest and has been investigated for a long time in cognitive psychology, and more recently, also in complexity science. However, the roles of partner feedback information in cooperative rhythm production remain unclear. In what ways is producing rhythm by yourself different from doing so cooperatively? How does a partner’s rhythm affect you? Does the method of interaction, aurally or visually, affect the final cooperative rhythm? This study addresses these essential questions through conducting alternate and continuous tapping experiments. In our alternate tapping experiments, participants were instructed to tap a pressure sensor, alternately (i) with a constant-paced metronome (ATm), (ii) with a metronome that ticks after the elapse of a certain time period from the participant’s tap (ATf), or (iii) with a partner (ATp). In the continuous tapping experiments, participants were instructed to tap at a constant pace (CT). The rhythm information (either that made by the tapping participants or the metronome) was relayed via either audio or visual signals. We evaluated the mean values and standard deviations of the time differences from stimulus to response (ds), and found that it was better under ATp conditions. Time-series analysis revealed that under ATp conditions, the inter-tap intervals of the two participants were correlated, and the values of ds varied in a mutually complementary manner. We also observed that participants depend on the partner more deeply when they receive their partners’ signals visually from the partner. Furthermore, under ATp conditions, a wider variety of complex rhythmic patterns were produced, suggesting that the emergence of complex rhythm patterns is highly impacted by mutual interaction between people and sensory modalities.