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Well everybody’s heard, about the bird

by on 2015/02/03

Recently, a rash of news outlets reported that even new-born chicks have a mental number line. As this finding is a little more esoteric than most of the scientific articles which make the headlines, it’s probably worth starting with a bit of background on the research itself.

It’s to do with how we appear to use space to represent numbers. A reasonable, although not uncontroversial, body of experimental evidence suggests that we cognitively represent large numbers over on the right side of space, whereas small numbers get represented on the left side of space (like on a ruler). This spatial coding of numbers has been referred to as the ‘mental number line’ by researchers, and has been a reasonably hot topic in cognitive psychology for the past few decades. As with many aspects of cognitive psychology, the debate has raged as to whether this number line is innate (similar regions of the brain deal with spatial tasks and numerical tasks) or learned (individuals who were educated in languages which are read from right-to-left, such as Arabic, show an opposite effect and seem to represent large numbers on the left and small numbers on the right). Well this is all very interesting, but rarely newsworthy, science. By contrast, this recent demonstration that new-born chicks appear to have a mental number line certainly got coverage in all the major news outlets.

The study itself was an elegant one – freshly-hatched chicks were trained to find food behind a panel which had five small dots on it, straight ahead of them. Then, they were placed in front of pairs of identical panels side by side which also had dots on them. When these panels each had a small number of dots, the chicks consistently chose to look behind the left-side panel. When the panels had a larger number of dots, they consistently walked behind the right-side panel. As the panels were the same, there was no reason to choose one more than the other, and the fact that the chicks chose in a way that seemed consistent with the ‘direction’ of the mental number line seems more than coincidental. And, given that humans show similar behaviour (in more human-centric behavioural tasks than looking for food), the authors suggest that this evidence for this numerical-spatial mapping in chicks suggests that the mental number line might be far older, in evolutionary terms, than previously thought. Personally, I feel that this conclusion is a little strong, given that many physical properties can evolve independently in separate species long after they have diverged from a common ancestor (known as ‘convergent evolution’ – the classic example of which comes from birds and bats, who share no common ancestor with wings).

The news coverage from the various outlets was, on the whole, excellent. The BBC, Daily Mail, and New York Times all cover the details of the experiment in an impressive level of detail. The accuracy and depth of the reporting was probably down to several factors. For one, the science behind the story doesn’t offer any glimmers of hope about the future of mankind and/or any insight into how to improve the lives of humans. The fundamental (and by fundamental, I mean lacking any obvious application) nature of this elegant study just doesn’t offer the temptation to report conclusions which vastly outstrip the data. Even the ever-popular ‘animals are more similar to humans than we previously thought’ angle is largely avoided. In addition to the nature of the research itself, it is likely that the good reporting was due, at least in part, to some careful management from the authors. All of the articles had not only the same images, but also an excellent video showing the training and test portions of the experiment. In addition to these materials, the lead author has provided interviews and quotes to the outlets or their sources. These strategies may well serve to minimise the likelihood of misunderstandings with the reporters.

Rugani, R. et al. (2015). Number-space mapping in the newborn chick resembles humans’ mental number line. Science. DOI:10.1126/science.aaa1379

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