The ability to learn patterns, ultimately the rules of language has rarely been studied in new world primates. In this study the researchers use species specific sounds/tones to determine if the squirrel monkeys were able to decipher when the correct order and incorrect order of these sounds were played. This is the first study that has used species specific frequencies in order to test their abilities. Other studies relied on humans producing syllables, which may not have been the most appropriate way to measure the monkeys’ capabilities.
Two ordered sound patterns were tested with the same rule being applied of A Bn A.
Test 1 – Low Tone= A, and High Tone = B (eg. Low, High, High, High, Low)
Test 2 – High Tone = A and Low Tone = B (eg. High, Low, Low, High)
The results suggest that the monkeys were able to consistently decipher when the rules were being broken in both the test settings.
These finding suggests that the ancestor of both squirrel monkeys and humans which existed approximately 36 million years ago would also have been able to understand the rules involved in pattern learning, thus most living apes and monkeys today should also be able to do this. This skill may have evolved as a cognitive ability rather than a direct pre-cursor to language.
Ravignani, A., Sonnweber, RS., Stobbe, N. and Fitch, TW (2013). Action at a distance: dependency sensitivity in a New World primate. Biology Letters. 9. 20130852
Ruth Sonnweber, one of the scientists from this study is now continuing similar work here with our squirrel monkeys in Living Links, however instead of sound stimuli she has been using touch screen to determine their ability to learn patterns.