Pigeons (Columba livia) can learn to distinguish real words from non-words by visually processing their letter combinations, according to a surprising new study led by University of Otago researchers.
Damian Scarf et al. demonstrate that pigeons (Columba livia) trained to discriminate words from non-words picked up on the orthographic properties that define words and used this knowledge to identify words they had never seen before. Image credit: Damian Scarf / University of Otago.
Dr. Damian Scarf of the University of Otago’s Department of Psychology, the study’s first author, and his colleagues from Germany and New Zealand found that pigeons’ performance was on a par with that previously reported in baboons for this type of complex task.
Their study, published in the Proceedings of the National Academy of Sciences, is the first to identify a non-primate species as having ‘orthographic’ abilities.
In the experiment, pigeons were trained to peck four-letter English words as they came up on a screen, or to instead peck a symbol when a four-letter non-word, such as ‘URSP’ was displayed.
The scientists added words one by one with the four pigeons in the study eventually building vocabularies ranging from 26 to 58 words and over 8,000 non-words.
To check whether the pigeons were learning to distinguish words from non-words rather than merely memorizing them, they introduced words the birds had never seen before.
The pigeons correctly identified the new words as words at a rate significantly above chance.
According to Dr. Scarf, they performed this feat by tracking the statistical likelihood that ‘bigrams,’ letter pairs such as ‘EN’ and ‘AL’, were more likely associated with words or non-words.
Co-author Prof. Onur Güntürkün, from the Department of Biopsychology at the Ruhr-University Bochum, Germany, said “that pigeons — separated by 300 million years of evolution from humans and having vastly different brain architectures — show such a skill as orthographic processing is astonishing.”
“We may have to seriously re-think the use of the term ‘bird brain’ as a put down,” added study senior author Prof. Michael Colombo, from the University of Otago’s Department of Psychology.
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Damian Scarf et al. Orthographic processing in pigeons (Columba livia). PNAS, published online September 16, 2016; doi: 10.1073/pnas.1607870113
