Age-dependent change in attention paid to vocal exchange rules in Japanese macaques

Abstract : The mechanisms underlying vocal development in nonhuman primates, so-called ‘non-learners’, are of special interest because they give an insight in how social factors can shape the expression of an already genetically determined vocal repertoire. Interestingly, recent studies suggest that the acquisition of the complex rules governing vocal exchanges (i.e. context-specific temporal and structural acoustic adjustments) may result from a socially guided development process, with social experience and parental selective feedback playing a key-role. Among those conversational rules, call matching is a particularly remarkable phenomenon in Japanese macaques (Macaca fuscata), with interacting adult females matching the frequency range pattern of their own call with another female’s preceding call. Here, we investigated whether fine-tuned acoustic adjustments during vocal exchanges in Japanese macaques are subject to developmental processes, specifically testing for differences in how individuals of different age classes discriminate between vocal exchanges following or not the matching rule. We performed playback experiments in 10 adult and 10 one-year old captive Japanese macaque females. Each subject was successively exposed to two stimuli: a pair of calls respecting call matching (i.e. two calls from two individuals with matched frequency ranges) and another pair of calls that did not. Only adults displayed different levels of interest. The latency to look towards the loudspeaker was shorter, and the duration of the directed gaze was longer, after the playback that violated the matching expectation in adults, but not in juveniles. Our findings support the conclusion that the matching rule is relevant for adults, but not for socially inexperienced young monkeys who may not have had enough experience of the conversational rules governing vocal exchanges yet.
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https://hal-univ-rennes1.archives-ouvertes.fr/hal-01511457
Contributeur : Antoine L'Azou <>
Soumis le : vendredi 21 avril 2017 - 09:51:42
Dernière modification le : mardi 26 septembre 2017 - 01:34:02

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Hélène Bouchet, Hiroki Koda, Alban Lemasson. Age-dependent change in attention paid to vocal exchange rules in Japanese macaques. Animal Behaviour, Elsevier Masson, 2017, 129, pp.81-92. 〈10.1016/j.anbehav.2017.05.012〉. 〈hal-01511457〉

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