Short description: Budgerigars can learn abstract rules in acoustic strings, zebra finches focus on the positional information.

Abstract:

The ability to abstract a rule that defines the structure of strings of sounds is a core mechanism underlying the language faculty, but might not be specific to language learning or even to humans. Up until now, it is unclear whether and to what extent non-human animals possess the ability to abstract a rule defining the relationship among arbitrary auditory items in a string and to generalize this rule to strings of acoustically novel items (ten Cate & Okanoya, 2012; ten Cate, 2014). In this study we tested both a songbird (zebra finch) as well as a parrot species (budgerigar) on these rule learning abilities. Subjects were trained in a go/no-go design to discriminate between two sets of sound strings that followed either an XYX or an XXY structure. After this discrimination was acquired, each subject received a number of test strings (mixed with the training strings) that followed the same structural rules, but consisted of either new combinations of known elements or of novel elements belonging to other categories. Both species learned to discriminate between the two stimulus sets during training. However, their responses to the test strings were strikingly different. Zebra finches categorized test stimuli with known elements by the positions that these elements occupied in the training strings. A subsequent experiment with artificially created sound elements showed that this was independent of whether the strings consisted of conspecific or unkown sounds. In contrast, the budgerigars categorized both novel combinations of familiar elements as well as strings consisting of novel elements by their underlying structure. They thus abstracted the relationship among items in the XYX and XXY structures, indicating a level of abstraction comparable to analogical reasoning, a cognitive ability long thought to be unique for humans and thus far only known from great apes and crows (Thompson & Oden 2000; Smirnova et al; 2015). Our study is the first clear indication that abstract rule learning in auditory strings is not specific to language or to humans.

References

Smirnova, A., Zorina, Z., Obozova, B., & Wasserman, E. (2015). Crows spontaneously exhibit analogical reasoning. Current Biology, 25, 1-5.

ten Cate, C. (2014). On the phonetic and syntactic processing abilities of birds: from songs to speech and artificial grammars. Curr. Opin. Neurobiol. 28, 157-164.

ten Cate, C., & Okanoya, K. (2012). Revisiting the syntactic abilities of non- human animals: natural vocalizations and artificial grammar learning. Phil.Trans. R. Soc. B., 367(1598), 1984-1994.

Thompson, R.K.R., & Oden, D.L. (2000). Categorical perception and conceptual judgments by nonhuman primates: The paleological monkey and the analogical ape. Cogn. Sci. 24, 363–396.

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Citation:

Spierings M. and ten Cate C. (2016). Rule Learning In Birds: Zebra Finches Generalize By Positional Similarities, Budgerigars By The Structural Rules.. In S.G. Roberts, C. Cuskley, L. McCrohon, L. Barceló-Coblijn, O. Fehér & T. Verhoef (eds.) The Evolution of Language: Proceedings of the 11th International Conference (EVOLANG11). Available online: http://evolang.org/neworleans/papers/15.html