Andrea Ravignani

Publications

Displaying 1 - 34 of 34
  • Anichini, M., De Heer Kloots, M., & Ravignani, A. (2020). Interactive rhythms in the wild, in the brain, and in silico. Canadian Journal of Experimental Psychology, 74(3), 170-175. doi:10.1037/cep0000224.

    Abstract

    There are some historical divisions in methods, rationales, and purposes between studies on comparative cognition and behavioural ecology. In turn, the interaction between these two branches and studies from mathematics, computation and neuroscience is not usual. In this short piece, we attempt to build bridges among these disciplines. We present a series of interconnected vignettes meant to illustrate how a more interdisciplinary approach looks like when successful, and its advantages. Concretely, we focus on a recent topic, namely animal rhythms in interaction, studied under different approaches. We showcase 5 research efforts, which we believe successfully link 5 particular Scientific areas of rhythm research conceptualized as: Social neuroscience, Detailed rhythmic quantification, Ontogeny, Computational approaches and Spontaneous interactions. Our suggestions will hopefully spur a ‘Comparative rhythms in interaction’ field, which can integrate and capitalize on knowledge from zoology, comparative psychology, neuroscience, and computation.
  • De Boer, B., Thompson, B., Ravignani, A., & Boeckx, C. (2020). Analysis of mutation and fixation for language. In A. Ravignani, C. Barbieri, M. Flaherty, Y. Jadoul, E. Lattenkamp, H. Little, M. Martins, K. Mudd, & T. Verhoef (Eds.), The Evolution of Language: Proceedings of the 13th International Conference (Evolang13) (pp. 56-58). Nijmegen: The Evolution of Language Conferences.
  • De Boer, B., Thompson, B., Ravignani, A., & Boeckx, C. (2020). Evolutionary dynamics do not motivate a single-mutant theory of human language. Scientific Reports, 10: 451. doi:10.1038/s41598-019-57235-8.

    Abstract

    One of the most controversial hypotheses in cognitive science is the Chomskyan evolutionary conjecture that language arose instantaneously in humans through a single mutation. Here we analyze the evolutionary dynamics implied by this hypothesis, which has never been formalized before. The hypothesis supposes the emergence and fixation of a single mutant (capable of the syntactic operation Merge) during a narrow historical window as a result of frequency-independent selection under a huge fitness advantage in a population of an effective size no larger than ~15 000 individuals. We examine this proposal by combining diffusion analysis and extreme value theory to derive a probabilistic formulation of its dynamics. We find that although a macro-mutation is much more likely to go to fixation if it occurs, it is much more unlikely a priori than multiple mutations with smaller fitness effects. The most likely scenario is therefore one where a medium number of mutations with medium fitness effects accumulate. This precise analysis of the probability of mutations occurring and going to fixation has not been done previously in the context of the evolution of language. Our results cast doubt on any suggestion that evolutionary reasoning provides an independent rationale for a single-mutant theory of language.

    Additional information

    Supplementary material
  • Garcia, M., & Ravignani, A. (2020). Acoustic allometry and vocal learning in mammals. Biology Letters, 16: 20200081. doi:10.1098/rsbl.2020.0081.

    Abstract

    Acoustic allometry is the study of how animal vocalisations reflect their body size. A key aim of this research is to identify outliers to acoustic allometry principles and pinpoint the evolutionary origins of such outliers. A parallel strand of research investigates species capable of vocal learning, the experience-driven ability to produce novel vocal signals through imitation or modification of existing vocalisations. Modification of vocalizations is a common feature found when studying both acoustic allometry and vocal learning. Yet, these two fields have only been investigated separately to date. Here, we review and connect acoustic allometry and vocal learning across mammalian clades, combining perspectives from bioacoustics, anatomy and evolutionary biology. Based on this, we hypothesize that, as a precursor to vocal learning, some species might have evolved the capacity for volitional vocal modulation via sexual selection for ‘dishonest’ signalling. We provide preliminary support for our hypothesis by showing significant associations between allometric deviation and vocal learning in a dataset of 164 mammals. Our work offers a testable framework for future empirical research linking allometric principles with the evolution of vocal learning.
  • Garcia, M., Theunissen, F., Sèbe, F., Clavel, J., Ravignani, A., Marin-Cudraz, T., Fuchs, J., & Mathevon, N. (2020). Evolution of communication signals and information during species radiation. Nature Communications, 11: 4970. doi:10.1038/s41467-020-18772-3.

    Abstract

    Communicating species identity is a key component of many animal signals. However, whether selection for species recognition systematically increases signal diversity during clade radiation remains debated. Here we show that in woodpecker drumming, a rhythmic signal used during mating and territorial defense, the amount of species identity information encoded remained stable during woodpeckers’ radiation. Acoustic analyses and evolutionary reconstructions show interchange among six main drumming types despite strong phylogenetic contingencies, suggesting evolutionary tinkering of drumming structure within a constrained acoustic space. Playback experiments and quantification of species discriminability demonstrate sufficient signal differentiation to support species recognition in local communities. Finally, we only find character displacement in the rare cases where sympatric species are also closely related. Overall, our results illustrate how historical contingencies and ecological interactions can promote conservatism in signals during a clade radiation without impairing the effectiveness of information transfer relevant to inter-specific discrimination.
  • Geambasu, A., Toron, L., Ravignani, A., & Levelt, C. C. (2020). Rhythmic recursion? Human sensitivity to a Lindenmayer grammar with self-similar structure in a musical task. Music & Science. doi:10.1177%2F2059204320946615.

    Abstract

    Processing of recursion has been proposed as the foundation of human linguistic ability. Yet this ability may be shared with other domains, such as the musical or rhythmic domain. Lindenmayer grammars (L-systems) have been proposed as a recursive grammar for use in artificial grammar experiments to test recursive processing abilities, and previous work had shown that participants are able to learn such a grammar using linguistic stimuli (syllables). In the present work, we used two experimental paradigms (a yes/no task and a two-alternative forced choice) to test whether adult participants are able to learn a recursive Lindenmayer grammar composed of drum sounds. After a brief exposure phase, we found that participants at the group level were sensitive to the exposure grammar and capable of distinguishing the grammatical and ungrammatical test strings above chance level in both tasks. While we found evidence of participants’ sensitivity to a very complex L-system grammar in a non-linguistic, potentially musical domain, the results were not robust. We discuss the discrepancy within our results and with the previous literature using L-systems in the linguistic domain. Furthermore, we propose directions for future music cognition research using L-system grammars.
  • De Heer Kloots, M., Carlson, D., Garcia, M., Kotz, S., Lowry, A., Poli-Nardi, L., De Reus, K., Rubio-García, A., Sroka, M., Varola, M., & Ravignani, A. (2020). Rhythmic perception, production and interactivity in harbour and grey seals. In A. Ravignani, C. Barbieri, M. Flaherty, Y. Jadoul, E. Lattenkamp, H. Little, M. Martins, K. Mudd, & T. Verhoef (Eds.), The Evolution of Language: Proceedings of the 13th International Conference (Evolang13) (pp. 59-62). Nijmegen: The Evolution of Language Conferences.
  • Heinrich, T., Ravignani, A., & Hanke, F. H. (2020). Visual timing abilities of a harbour seal (Phoca vitulina) and a South African fur seal (Arctocephalus pusillus pusillus) for sub- and supra-second time intervals. Animal Cognition, 23(5), 851-859. doi:10.1007/s10071-020-01390-3.

    Abstract

    Timing is an essential parameter influencing many behaviours. A previous study demonstrated a high sensitivity of a phocid, the harbour seal (Phoca vitulina), in discriminating time intervals. In the present study, we compared the harbour seal’s timing abilities with the timing abilities of an otariid, the South African fur seal (Arctocephalus pusillus pusillus). This comparison seemed essential as phocids and otariids differ in many respects and might, thus, also differ regarding their timing abilities. We determined time difference thresholds for sub- and suprasecond time intervals marked by a white circle on a black background displayed for a specific time interval on a monitor using a staircase method. Contrary to our expectation, the timing abilities of the fur seal and the harbour seal were comparable. Over a broad range of time intervals, 0.8–7 s in the fur seal and 0.8–30 s in the harbour seal, the difference thresholds followed Weber’s law. In this range, both animals could discriminate time intervals differing only by 12 % and 14 % on average. Timing might, thus be a fundamental cue for pinnipeds in general to be used in various contexts, thereby complementing information provided by classical sensory systems. Future studies will help to clarify if timing is indeed involved in foraging decisions or the estimation of travel speed or distance.

    Additional information

    supplementary material
  • Hoeksema, N., Villanueva, S., Mengede, J., Salazar Casals, A., Rubio-García, A., Curcic-Blake, B., Vernes, S. C., & Ravignani, A. (2020). Neuroanatomy of the grey seal brain: Bringing pinnipeds into the neurobiological study of vocal learning. In A. Ravignani, C. Barbieri, M. Flaherty, Y. Jadoul, E. Lattenkamp, H. Little, M. Martins, K. Mudd, & T. Verhoef (Eds.), The Evolution of Language: Proceedings of the 13th International Conference (Evolang13) (pp. 162-164). Nijmegen: The Evolution of Language Conferences.
  • Jacoby, N., Margulis, E. H., Clayton, M., Hannon, E., Honing, H., Iversen, J., Klein, T. R., Mehr, S. A., Pearson, L., Peretz, I., Perlman, M., Polak, R., Ravignani, A., Savage, P. E., Steingo, G., Stevens, C. J., Trainor, L., Trehub, S., Veal, M., & Wald-Fuhrmann, M. (2020). Cross-cultural work in music cognition: Challenges, insights, and recommendations. Music Perception, 37(3), 185-195. doi:10.1525/mp.2020.37.3.185.

    Abstract

    Many foundational questions in the psychology of music require cross-cultural approaches, yet the vast majority of work in the field to date has been conducted with Western participants and Western music. For cross-cultural research to thrive, it will require collaboration between people from different disciplinary backgrounds, as well as strategies for overcoming differences in assumptions, methods, and terminology. This position paper surveys the current state of the field and offers a number of concrete recommendations focused on issues involving ethics, empirical methods, and definitions of “music” and “culture.”
  • Ravignani, A., & Kotz, S. (2020). Breathing, voice and synchronized movement. Proceedings of the National Academy of Sciences of the United States of America, 117(38), 23223-23224. doi:10.1073/pnas.2011402117.

    Additional information

    Pouw_etal_reply.pdf
  • Ravignani, A., Barbieri, C., Flaherty, M., Jadoul, Y., Lattenkamp, E. Z., Little, H., Martins, M., Mudd, K., & Verhoef, T. (Eds.). (2020). The Evolution of Language: Proceedings of the 13th International Conference (Evolang13). Nijmegen: The Evolution of Language Conferences. doi:10.17617/2.3190925.

    Additional information

    Link to pdf on EvoLang Website
  • De Reus, K., Carlson, D., Jadoul, Y., Lowry, A., Gross, S., Garcia, M., Salazar Casals, A., Rubio-García, A., Haas, C. E., De Boer, B., & Ravignani, A. (2020). Relationships between vocal ontogeny and vocal tract anatomy in harbour seals (Phoca vitulina). In A. Ravignani, C. Barbieri, M. Flaherty, Y. Jadoul, E. Lattenkamp, H. Little, M. Martins, K. Mudd, & T. Verhoef (Eds.), The Evolution of Language: Proceedings of the 13th International Conference (Evolang13) (pp. 63-66). Nijmegen: The Evolution of Language Conferences.
  • Wilson, B., Spierings, M., Ravignani, A., Mueller, J. L., Mintz, T. H., Wijnen, F., Van der Kant, A., Smith, K., & Rey, A. (2020). Non‐adjacent dependency learning in humans and other animals. Topics in Cognitive Science, 12(3), 843-858. doi:10.1111/tops.12381.

    Abstract

    Learning and processing natural language requires the ability to track syntactic relationships between words and phrases in a sentence, which are often separated by intervening material. These nonadjacent dependencies can be studied using artificial grammar learning paradigms and structured sequence processing tasks. These approaches have been used to demonstrate that human adults, infants and some nonhuman animals are able to detect and learn dependencies between nonadjacent elements within a sequence. However, learning nonadjacent dependencies appears to be more cognitively demanding than detecting dependencies between adjacent elements, and only occurs in certain circumstances. In this review, we discuss different types of nonadjacent dependencies in language and in artificial grammar learning experiments, and how these differences might impact learning. We summarize different types of perceptual cues that facilitate learning, by highlighting the relationship between dependent elements bringing them closer together either physically, attentionally, or perceptually. Finally, we review artificial grammar learning experiments in human adults, infants, and nonhuman animals, and discuss how similarities and differences observed across these groups can provide insights into how language is learned across development and how these language‐related abilities might have evolved.
  • Lameira, A. R., Eerola, T., & Ravignani, A. (2019). Coupled whole-body rhythmic entrainment between two chimpanzees. Scientific Reports, 9: 18914. doi:10.1038/s41598-019-55360-y.

    Abstract

    Dance is an icon of human expression. Despite astounding diversity around the world’s cultures and dazzling abundance of reminiscent animal systems, the evolution of dance in the human clade remains obscure. Dance requires individuals to interactively synchronize their whole-body tempo to their partner’s, with near-perfect precision. This capacity is motorically-heavy, engaging multiple neural circuitries, but also dependent on an acute socio-emotional bond between partners. Hitherto, these factors helped explain why no dance forms were present amongst nonhuman primates. Critically, evidence for conjoined full-body rhythmic entrainment in great apes that could help reconstruct possible proto-stages of human dance is still lacking. Here, we report an endogenously-effected case of ritualized dance-like behaviour between two captive chimpanzees – synchronized bipedalism. We submitted video recordings to rigorous time-series analysis and circular statistics. We found that individual step tempo was within the genus’ range of “solo” bipedalism. Between-individual analyses, however, revealed that synchronisation between individuals was non-random, predictable, phase concordant, maintained with instantaneous centi-second precision and jointly regulated, with individuals also taking turns as “pace-makers”. No function was apparent besides the behaviour’s putative positive social affiliation. Our analyses show a first case of spontaneous whole-body entrainment between two ape peers, thus providing tentative empirical evidence for phylogenies of human dance. Human proto-dance, we argue, may have been rooted in mechanisms of social cohesion among small groups that might have granted stress-releasing benefits via gait-synchrony and mutual-touch. An external sound/musical beat may have been initially uninvolved. We discuss dance evolution as driven by ecologically-, socially- and/or culturally-imposed “captivity”.

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    Supplementary Information
  • Larsson, M., Richter, J., & Ravignani, A. (2019). Bipedal steps in the development of rhythmic behavior in humans. Music & Science, 2, 1-14. doi:10.1177/2059204319892617.

    Abstract

    We contrast two related hypotheses of the evolution of dance: H1: Maternal bipedal walking influenced the fetal experience of sound and associated movement patterns; H2: The human transition to bipedal gait produced more isochronous/predictable locomotion sound resulting in early music-like behavior associated with the acoustic advantages conferred by moving bipedally in pace. The cadence of walking is around 120 beats per minute, similar to the tempo of dance and music. Human walking displays long-term constancies. Dyads often subconsciously synchronize steps. The major amplitude component of the step is a distinctly produced beat. Human locomotion influences, and interacts with, emotions, and passive listening to music activates brain motor areas. Across dance-genres the footwork is most often performed in time to the musical beat. Brain development is largely shaped by early sensory experience, with hearing developed from week 18 of gestation. Newborns reacts to sounds, melodies, and rhythmic poems to which they have been exposed in utero. If the sound and vibrations produced by footfalls of a walking mother are transmitted to the fetus in coordination with the cadence of the motion, a connection between isochronous sound and rhythmical movement may be developed. Rhythmical sounds of the human mother locomotion differ substantially from that of nonhuman primates, while the maternal heartbeat heard is likely to have a similar isochronous character across primates, suggesting a relatively more influential role of footfall in the development of rhythmic/musical abilities in humans. Associations of gait, music, and dance are numerous. The apparent absence of musical and rhythmic abilities in nonhuman primates, which display little bipedal locomotion, corroborates that bipedal gait may be linked to the development of rhythmic abilities in humans. Bipedal stimuli in utero may primarily boost the ontogenetic development. The acoustical advantage hypothesis proposes a mechanism in the phylogenetic development.
  • Ravignani, A. (2019). [Review of the book Animal beauty: On the evolution of bological aesthetics by C. Nüsslein-Volhard]. Animal Behaviour, 155, 171-172. doi:10.1016/j.anbehav.2019.07.005.
  • Ravignani, A. (2019). [Review of the book The origins of musicality ed. by H. Honing]. Perception, 48(1), 102-105. doi:10.1177/0301006618817430.
  • Ravignani, A. (2019). Everything you always wanted to know about sexual selection in 129 pages [Review of the book Sexual selection: A very short introduction by M. Zuk and L. W. Simmons]. Journal of Mammalogy, 100(6), 2004-2005. doi:10.1093/jmammal/gyz168.
  • Ravignani, A., & Gamba, M. (2019). Evolving musicality [Review of the book The evolving animal orchestra: In search of what makes us musical by Henkjan Honing]. Trends in Ecology and Evolution, 34(7), 583-584. doi:10.1016/j.tree.2019.04.016.
  • Ravignani, A., Verga, L., & Greenfield, M. D. (2019). Interactive rhythms across species: The evolutionary biology of animal chorusing and turn-taking. Annals of the New York Academy of Sciences, 1453(1), 12-21. doi:10.1111/nyas.14230.

    Abstract

    The study of human language is progressively moving toward comparative and interactive frameworks, extending the concept of turn‐taking to animal communication. While such an endeavor will help us understand the interactive origins of language, any theoretical account for cross‐species turn‐taking should consider three key points. First, animal turn‐taking must incorporate biological studies on animal chorusing, namely how different species coordinate their signals over time. Second, while concepts employed in human communication and turn‐taking, such as intentionality, are still debated in animal behavior, lower level mechanisms with clear neurobiological bases can explain much of animal interactive behavior. Third, social behavior, interactivity, and cooperation can be orthogonal, and the alternation of animal signals need not be cooperative. Considering turn‐taking a subset of chorusing in the rhythmic dimension may avoid overinterpretation and enhance the comparability of future empirical work.
  • Ravignani, A., Chiandetti, C., & Kotz, S. (2019). Rhythm and music in animal signals. In J. Choe (Ed.), Encyclopedia of Animal Behavior (vol. 1) (2nd ed., pp. 615-622). Amsterdam: Elsevier.
  • Ravignani, A. (2019). Rhythm and synchrony in animal movement and communication. Current Zoology, 65(1), 77-81. doi:10.1093/cz/zoy087.

    Abstract

    Animal communication and motoric behavior develop over time. Often, this temporal dimension has communicative relevance and is organized according to structural patterns. In other words, time is a crucial dimension for rhythm and synchrony in animal movement and communication. Rhythm is defined as temporal structure at a second-millisecond time scale (Kotz et al. 2018). Synchrony is defined as precise co-occurrence of 2 behaviors in time (Ravignani 2017). Rhythm, synchrony, and other forms of temporal interaction are taking center stage in animal behavior and communication. Several critical questions include, among others: what species show which rhythmic predispositions? How does a species’ sensitivity for, or proclivity towards, rhythm arise? What are the species-specific functions of rhythm and synchrony, and are there functional trends across species? How did similar or different rhythmic behaviors evolved in different species? This Special Column aims at collecting and contrasting research from different species, perceptual modalities, and empirical methods. The focus is on timing, rhythm and synchrony in the second-millisecond range. Three main approaches are commonly adopted to study animal rhythms, with a focus on: 1) spontaneous individual rhythm production, 2) group rhythms, or 3) synchronization experiments. I concisely introduce them below (see also Kotz et al. 2018; Ravignani et al. 2018).
  • Ravignani, A., Dalla Bella, S., Falk, S., Kello, C. T., Noriega, F., & Kotz, S. A. (2019). Rhythm in speech and animal vocalizations: A cross‐species perspective. Annals of the New York Academy of Sciences, 1453(1), 79-98. doi:10.1111/nyas.14166.

    Abstract

    Why does human speech have rhythm? As we cannot travel back in time to witness how speech developed its rhythmic properties and why humans have the cognitive skills to process them, we rely on alternative methods to find out. One powerful tool is the comparative approach: studying the presence or absence of cognitive/behavioral traits in other species to determine which traits are shared between species and which are recent human inventions. Vocalizations of many species exhibit temporal structure, but little is known about how these rhythmic structures evolved, are perceived and produced, their biological and developmental bases, and communicative functions. We review the literature on rhythm in speech and animal vocalizations as a first step toward understanding similarities and differences across species. We extend this review to quantitative techniques that are useful for computing rhythmic structure in acoustic sequences and hence facilitate cross‐species research. We report links between vocal perception and motor coordination and the differentiation of rhythm based on hierarchical temporal structure. While still far from a complete cross‐species perspective of speech rhythm, our review puts some pieces of the puzzle together.
  • Ravignani, A. (2019). Seeking shared ground in space. Science, 366(6466), 696. doi:10.1126/science.aay6955.
  • Ravignani, A. (2019). Humans and other musical animals [Review of the book The evolving animal orchestra: In search of what makes us musical by Henkjan Honing]. Current Biology, 29(8), R271-R273. doi:10.1016/j.cub.2019.03.013.
  • Ravignani, A., & De Reus, K. (2019). Modelling animal interactive rhythms in communication. Evolutionary Bioinformatics, 15, 1-14. doi:10.1177/1176934318823558.

    Abstract

    Time is one crucial dimension conveying information in animal communication. Evolution has shaped animals’ nervous systems to produce signals with temporal properties fitting their socio-ecological niches. Many quantitative models of mechanisms underlying rhythmic behaviour exist, spanning insects, crustaceans, birds, amphibians, and mammals. However, these computational and mathematical models are often presented in isolation. Here, we provide an overview of the main mathematical models employed in the study of animal rhythmic communication among conspecifics. After presenting basic definitions and mathematical formalisms, we discuss each individual model. These computational models are then compared using simulated data to uncover similarities and key differences in the underlying mechanisms found across species. Our review of the empirical literature is admittedly limited. We stress the need of using comparative computer simulations – both before and after animal experiments – to better understand animal timing in interaction. We hope this article will serve as a potential first step towards a common computational framework to describe temporal interactions in animals, including humans.

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    Supplemental material files
  • Ravignani, A., Kello, C. T., De Reus, K., Kotz, S. A., Dalla Bella, S., Mendez-Arostegui, M., Rapado-Tamarit, B., Rubio-Garcia, A., & de Boer, B. (2019). Ontogeny of vocal rhythms in harbor seal pups: An exploratory study. Current Zoology, 65(1), 107-120. doi:10.1093/cz/zoy055.

    Abstract

    Puppyhood is a very active social and vocal period in a harbor seal's life Phoca vitulina. An important feature of vocalizations is their temporal and rhythmic structure, and understanding vocal timing and rhythms in harbor seals is critical to a cross-species hypothesis in evolutionary neuroscience that links vocal learning, rhythm perception, and synchronization. This study utilized analytical techniques that may best capture rhythmic structure in pup vocalizations with the goal of examining whether (1) harbor seal pups show rhythmic structure in their calls and (2) rhythms evolve over time. Calls of 3 wild-born seal pups were recorded daily over the course of 1-3 weeks; 3 temporal features were analyzed using 3 complementary techniques. We identified temporal and rhythmic structure in pup calls across different time windows. The calls of harbor seal pups exhibit some degree of temporal and rhythmic organization, which evolves over puppyhood and resembles that of other species' interactive communication. We suggest next steps for investigating call structure in harbor seal pups and propose comparative hypotheses to test in other pinniped species.
  • Ravignani, A., Filippi, P., & Fitch, W. T. (2019). Perceptual tuning influences rule generalization: Testing humans with monkey-tailored stimuli. i-Perception, 10(2), 1-5. doi:10.1177/2041669519846135.

    Abstract

    Comparative research investigating how nonhuman animals generalize patterns of auditory stimuli often uses sequences of human speech syllables and reports limited generalization abilities in animals. Here, we reverse this logic, testing humans with stimulus sequences tailored to squirrel monkeys. When test stimuli are familiar (human voices), humans succeed in two types of generalization. However, when the same structural rule is instantiated over unfamiliar but perceivable sounds within squirrel monkeys’ optimal hearing frequency range, human participants master only one type of generalization. These findings have methodological implications for the design of comparative experiments, which should be fair towards all tested species’ proclivities and limitations.

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    Supplemental material files
  • Ravignani, A. (2019). Singing seals imitate human speech. Journal of Experimental Biology, 222: jeb208447. doi:10.1242/jeb.208447.
  • Ravignani, A. (2019). Timing of antisynchronous calling: A case study in a harbor seal pup (Phoca vitulina). Journal of Comparative Psychology, 133(2), 272-277. doi:10.1037/com0000160.

    Abstract

    Alternative mathematical models predict differences in how animals adjust the timing of their calls. Differences can be measured as the effect of the timing of a conspecific call on the rate and period of calling of a focal animal, and the lag between the two. Here, I test these alternative hypotheses by tapping into harbor seals’ (Phoca vitulina) mechanisms for spontaneous timing. Both socioecology and vocal behavior of harbor seals make them an interesting model species to study call rhythm and timing. Here, a wild-born seal pup was tested in controlled laboratory conditions. Based on previous recordings of her vocalizations and those of others, I designed playback experiments adapted to that specific animal. The call onsets of the animal were measured as a function of tempo, rhythmic regularity, and spectral properties of the playbacks. The pup adapted the timing of her calls in response to conspecifics’ calls. Rather than responding at a fixed time delay, the pup adjusted her calls’ onset to occur at a fraction of the playback tempo, showing a relative-phase antisynchrony. Experimental results were confirmed via computational modeling. This case study lends preliminary support to a classic mathematical model of animal behavior—Hamilton’s selfish herd—in the acoustic domain.
  • Ravignani, A. (2019). Understanding mammals, hands-on [Review of the book Mammalogy techniques lab manual by J. M. Ryan]. Journal of Mammalogy, 100(5), 1695-1696. doi:10.1093/jmammal/gyz132.
  • Reber, S. A., Šlipogor, V., Oh, J., Ravignani, A., Hoeschele, M., Bugnyar, T., & Fitch, W. T. (2019). Common marmosets are sensitive to simple dependencies at variable distances in an artificial grammar. Evolution and Human Behavior, 40(2), 214-221. doi:10.1016/j.evolhumbehav.2018.11.006.

    Abstract

    Recognizing that two elements within a sequence of variable length depend on each other is a key ability in understanding the structure of language and music. Perception of such interdependencies has previously been documented in chimpanzees in the visual domain and in human infants and common squirrel monkeys with auditory playback experiments, but it remains unclear whether it typifies primates in general. Here, we investigated the ability of common marmosets (Callithrix jacchus) to recognize and respond to such dependencies. We tested subjects in a familiarization-discrimination playback experiment using stimuli composed of pure tones that either conformed or did not conform to a grammatical rule. After familiarization to sequences with dependencies, marmosets spontaneously discriminated between sequences containing and lacking dependencies (‘consistent’ and ‘inconsistent’, respectively), independent of stimulus length. Marmosets looked more often to the sound source when hearing sequences consistent with the familiarization stimuli, as previously found in human infants. Crucially, looks were coded automatically by computer software, avoiding human bias. Our results support the hypothesis that the ability to perceive dependencies at variable distances was already present in the common ancestor of all anthropoid primates (Simiiformes).
  • Versace, E., Rogge, J. R., Shelton-May, N., & Ravignani, A. (2019). Positional encoding in cotton-top tamarins (Saguinus oedipus). Animal Cognition, 22, 825-838. doi:10.1007/s10071-019-01277-y.

    Abstract

    Strategies used in artificial grammar learning can shed light into the abilities of different species to extract regularities from the environment. In the A(X)nB rule, A and B items are linked, but assigned to different positional categories and separated by distractor items. Open questions are how widespread is the ability to extract positional regularities from A(X)nB patterns, which strategies are used to encode positional regularities and whether individuals exhibit preferences for absolute or relative position encoding. We used visual arrays to investigate whether cotton-top tamarins (Saguinusoedipus) can learn this rule and which strategies they use. After training on a subset of exemplars, two of the tested monkeys successfully generalized to novel combinations. These tamarins discriminated between categories of tokens with different properties (A, B, X) and detected a positional relationship between non-adjacent items even in the presence of novel distractors. The pattern of errors revealed that successful subjects used visual similarity with training stimuli to solve the task and that successful tamarins extracted the relative position of As and Bs rather than their absolute position, similarly to what has been observed in other species. Relative position encoding appears to be favoured in different tasks and taxa. Generalization, though, was incomplete, since we observed a failure with items that during training had always been presented in reinforced arrays, showing the limitations in grasping the underlying positional rule. These results suggest the use of local strategies in the extraction of positional rules in cotton-top tamarins.

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