Positional encoding in cotton-top tamarins (Saguinus oedipus)

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 ) n B 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 ) n B 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 ( Saguinus oedipus ) 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 A s and B s 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. Electronic supplementary material The online version of this article (10.1007/s10071-019-01277-y) contains supplementary material, which is available to authorized users.

Non‐adjacent Dependency Learning in Humans and Other Animals

“…Gómez found that in some conditions (see below) adults and infants are able to learn these nonadjacent dependencies, discriminating between sequences which conform to or violate the dependency. This result has been confirmed in further experiments involving adults (e.g., Frost & Monaghan, 2016; Gómez, 2002; Pena, Bonatti, Nespor, & Mehler, 2002; van den Bos, Christiansen, & Misyak, 2012; Vuong, Meyer, & Christiansen, 2016) and infants (e.g., Gómez, 2002; Gómez & Maye, 2005) as well as nonhuman animals (e.g., Milne et al., 2016; Newport et al., 2004; Ravignani, Sonnweber, Stobbe, & Fitch, 2013; Sonnweber, Ravignani, & Fitch, 2015; Versace, Rogge, Shelton‐May, & Ravignani, 2017), although successful learning only occurs under certain conditions (see Section 3, below).…”

“…By contrast, tamarins were able to learn the dependencies based on syllables and vowels, but not consonants, suggesting that the vowel sounds (including within syllables) might be particularly salient to the monkeys (Newport et al., 2004). Recently, nonadjacent dependency learning has been demonstrated in the visual modality in tamarins (Versace et al., 2017) and baboons (Malassis, Rey, & Fagot, 2018), suggesting that these abilities are not limited to the auditory domain. de la Mora and Toro (2013) presented rats with sequences of nonsense words of alternating consonants and vowels of the form “CVCVCV,” containing nonadjacent dependencies between either the vowels or the consonants.…”

Nonadjacent dependency processing in monkeys, apes, and humans

“…For example, a number of paradigms used passive learning of grammars [e.g., cotton-top tamarins, Saguinus oedipus ( 8 , 24 ); squirrel monkeys, Saimiri sciureus ( 5 )], while others actively trained subjects via operant conditioning [e.g., starlings, Sturnus vulgaris ( 35 ); rhesus macaques, Macaca mulatta ( 9 )]. In addition, some studies investigated sequence processing in the visual [e.g., chimpanzees ( 15 , 16 ); rats, Rattus norvegicus ( 36 ); cotton-top tamarins ( 12 )] rather than auditory domain [e.g., Bengalese finches, Lonchura striata domestica ( 14 )], and certain studies constructed their grammars from artificial stimuli [e.g., squirrel monkeys and common marmosets ( 5 , 6 )] as opposed to using vocalizations from the study species’ own repertoire [e.g., starlings ( 13 , 35 )]. While experimental design must account for the pertinent cognitive, behavioral, and morphological profiles of a study species, it is advantageous to keep all other factors as similar as possible when aiming to facilitate fair comparisons across species ( 19 – 23 ).…”

Emotional Voice Intonation: A Communication Code at the Origins of Speech Processing and Word-Meaning Associations?

“…To date, the majority of studies have found that, multiple species of animals are able to process regular grammars, specifically, (AB) n sequences (ravens, Corvus corax, Reber et al 2016; kea, Nestor notabilis, and pigeons, Columba livia, Stobbe et al 2012; cf. ten Cate and Okanoya 2012) and perceptual dependencies between edge stimuli in AB n A sequences both in the visual domain (chimpanzees, Pan troglodytes, Sonnweber et al 2015; cotton-top tamarins, Saguinus oedipus, Versace et al 2019) and in the auditory domain (squirrel monkeys, Saimiri sciureus, Ravignani et al 2013; cotton-top tamarins, Saguinus oedipus, Newport et al 2004; common marmosets, Callithrix jacchus, Reber et al 2019). In addition, although some research has suggested that birds are able to process supra-regular grammars (Abe and Watanabe 2011;Gentner et al 2006), subsequent studies have shown that these birds might have used simple strategies-that do not require any of the computational power at the level of supra-regular automata-to parse these structures (Ravignani et al 2015;Van Heijningen et al 2009).…”