Open Research Repository ORR
Not a member yet
2835 research outputs found
Sort by
Uncertainty quantification and posterior sampling for network reconstruction
No full textNetwork reconstruction is the task of inferring the unseen interactions between elements of a system, based only on their behaviour or dynamics. This inverse problem is in general ill-posed and admits many solutions for the same observation. Nevertheless, the vast majority of statistical methods proposed for this task—formulated as the inference of a graphical generative model—can only produce a ‘point estimate’, i.e. a single network considered the most likely. In general, this can give only a limited characterization of the reconstruction, since uncertainties and competing answers cannot be conveyed, even if their probabilities are comparable, while being structurally different. In this work, we present an efficient Markov-chain Monte–Carlo algorithm for sampling from posterior distributions of reconstructed networks, which is able to reveal the full population of answers for a given reconstruction problem, weighted according to their plausibilities. Our algorithm is general, since it does not rely on specific properties of particular generative models, and is specially suited for the inference of large and sparse networks, since in this case an iteration can be performed in time O(Nlog2 N) for a network of N nodes, instead of O(N2), as would be the case for a more naïve approach. We demonstrate the suitability of our method in providing uncertainties and consensus of solutions (which provably increases the reconstruction accuracy) in a variety of synthetic and empirical cases
Affective observation guides expectations about others' emotional reactions to unfamiliar action outcomes
No full textObserving others' emotional expressions facilitates individuals' expectations about the evaluations shared within a social group. This is useful for interpreting ambiguous cultural content, such as unfamiliar actions performed by others. This study investigated whether observed emotional reactions to instrumental actions are used to predict novel individuals' evaluations of those same actions (i.e., generalization), and whether they are more likely to be generalized for unfamiliar compared to familiar actions. Participants were presented with emotional expressions of observers reacting to individuals performing instrumental actions, before selecting the reaction they expected from a novel observer watching the same action performed by a new individual - generalization meaning that the novel observer was expected to elicit the same emotional expression as the initial observer. Experiment 1 found that negative reactions are generalized to predict negative evaluations of unfamiliar but not familiar actions, whereas Experiments 2 and 3 demonstrated differences in generalization and influence on expectations of positive and negative displays depending on whether familiar and unfamiliar actions were present. This study sheds light on the affective components of cultural learning, showing that the observation of others' emotional displays enables us to interpret unfamiliar social situations in the absence of direct communication
Context-dependent organization of birdsong:experimental evidence from the collared flycatcher, Ficedula albicollis
No full textWhile acoustic signals are highly flexible, their context-dependent changes remain poorly understood. Birdsong is a model of choice to explore these aspects. As repetition and diversity of song elements largely determine the overall characteristics of signals and such song characteristics as versatility and repertoire size can plastically change in different social contexts, we hypothesized that the repetition of syllables and syllable sequences could also be context dependent. Here, we used the song of the collared flycatcher as a study system. We recorded the song of focal males under different simulated sociosexual contexts (solo singing, intruder male, approaching female and counter-singing situations in the natural environment), and quantified the context-dependent changes in song structure. As well as the commonly used acoustic variables repertoire size, number of syllables in the song and versatility, we also measured the richness (number of different types) and abundance (number of occurrences) of the repeated syllables and syllable sequences in the song bout recorded in different social contexts. We found lower richness of short repeated sequences and a smaller repertoire size in the context of an approaching female compared to the solo context. Conversely, we found higher richness of long repeated sequences and songs with more syllables in counter-singing compared to the solo context in the song of the focal male. Our study provides evidence that the syllable sequences in the song bout can change depending on the social context in collared flycatchers. Our study also emphasizes the importance of considering the repetition-describing characteristics in addition to the commonly used acoustic characteristics when studying animal acoustic communication
