by Playfuls Staff |
26th April 2006
A remarkable discovery was revealed today by researchers from the University of Chicago and the University of California San Diego: the capacity of recognising and distinguishing between patterns of language organisation in Sturnus vulgaris, the common European starling. [more]
In the April 27, 2006, issue of Nature, the researchers show that these starlings, long known as virtuoso songbirds and expert mimics, can be trained to reliably discriminate between two different patterns of organizing the sounds they use to communicate.
The researchers focused on recursion, or center-embedding, a characteristic, found in all human languages. Recursion is one way of creating of new and grammatically correct meanings by inserting words and clauses within sentences - theoretically, without limit. So, for example, "The bird sang" can become "The bird the cat chased sang."
Although they are not known for the lilting beauty of their songs, starlings produce an amazing array of complex sounds, combining chirps, warbles, trills and whistles with rattling sounds.
To assess the birds' syntactical skills, the research team exploited the diverse sounds in starling songs. They recorded eight different 'rattles' and eight 'warbles' from a single male starling and combined them to construct a total of 16 artificial songs. These songs followed two different grammars, or patterning rules.
After 10,000 to 50,000 trials over several months, 9 of 11 tested starlings learned to distinguish the patterns. The birds were not simply memorizing particular sequences of rattles and warbles they could distinguish between different patterns even when presented with entirely new sequences of rattles and warbles. They were applying rules to solve the task.
The researchers also checked to see how the birds responded to "ungrammatical" strings, songs that violated the established rules. The starlings treated these differently, as expected if they had learned the patterns.
The experimenters then asked if the birds were capable of a key feature of human grammars. Could the starlings extrapolate these patterning rules to distinguish among longer strings? Remarkably, after learning the patterns with shorter songs made up of two pairs of rattles and warbles, the birds were able to recognize strings containing 6-to-8 song elements (abababab vs aaaabbbb).
The finding that starlings can grasp these grammatical rules shows that other animals share basic levels of pattern recognition with humans. "There might be no single property or processing capacity," the authors write, "that marks the many ways in which the complexity and detail of human language differs from non-human communication systems."
