Friday, August 6, 2010

Paul the Predicting Octopus?

[Posted by blog co-author]

With the recent World Cup, there had been a lot of hype going on about the divine precognitive powers of the seafood prophet - Paul the Octopus.

It is highly unlikely that this octopus can understand anything about the World Cup, soccer, countries or even the biology behind mussels. So how is it that Paul predicted 4 out of 6 matches correctly in Euro 2008, and a bewildering 8 out of 8 matches in the World Cup 2010? Surely there must be a supernatural force guiding the tentacles of Paul to reach out for the correct flag. Never mind the two times this force tricked his Cephalopod intelligence.

Lets see if we can find other possible explanations without involving the supernatural.
Paraphrased from Wikipedia: According to Etienne Roquain of Pierre and Marie Curie University in Paris, Paul could have been choosing boxes systematically—if not on the basis of football expertise, then perhaps on his attraction to the countries' flags or the food items offered. Shelagh Malham, research lecturer at the School of Ocean Sciences, Bangor University, states that octopuses are drawn to horizontal shapes. Octopuses are almost certainly colour blind but can distinguish brightness, size, shape and orientation.
It should be noted that Paul chose Germany 11 out of 14 times. The flag of Germany has three horizontal stripes - black, red and gold. He chose Spain 2 times, whose flag is brighter than that of Germany, as it has three horizontal stripes of red, gold (a darker shade but wider) and red again. It could be speculated that Paul was driven by the flag's brightness as Serbian flag has a horizontal strip of white, the brightest colour (along with strips of navy blue and red). But the catch is that Netherlands has a flag that's similar to Serbia, yet was on the losing side of the World Cup final.
Wikipedia: Octopus vulgaris is also equipped with sensitive chemoreceptors on its tentacles, which are used to taste food and smell the water. Biologist Volker Miske, of the University of Greifswald, suggests that minor chemical differences on the surface of each box might account for Paul's decisions. Bisikov states that Paul could be easily trained to choose the right box by smell. According to Paul's keepers, there are holes in the jars to help him choose. (From footnote: Paul's aquarium minders have confided that his choice of mussels from jars decorated with national flags was helped by holes in the jars.)
Despite attempts to perform these predictions as a blind experiments, they lack the credibility of a scientific experiment. As quoted from Wikipedia,
Theories to explain his behavior could have been systematically tested if Paul had repeated his selection many times, but he only selected one box per game. A scientific experiment would have been more vigilant about possible sources of bias, including the flag visuals and potential differences in the preparation of the food.
It should also be noted that the predictions could have influenced the players of the games psychologically, at least in the later stages when Paul became famous. However, it is clear that none of these needed the invocation of a supernatural force or the conclusion that the octopus himself had supernatural powers.

False Significance: Formally known as survivorship bias, it is the tendency of people to ignore a large number of failures while exalting one or a few successes. It is classified as a statistical artifact, or in other words, the problem of wrongly interpreting the statistical significance of an event. Paul became famous because of his correct predictions. However, statistically speaking, this is not very significant. To quote again from Wikipedia:
José Mérida, a data analyst from Guatemala City, used a coin tossing model to calculate that only 178 individuals are needed to have someone correctly guess/predict all the winners from a series of 8 matches; and points out that there were certainly thousands and thousands of individuals all over the world attempting to make these predictions during the 2010 FIFA World Cup.
In fact, Mani is a parrot in Singapore who correctly predicted the quarter-finals and semi-finals. And not to forget the thousands of people who place bets on each of the soccer matches. This shows that Paul's predictions are not significant, considering that he had equal chance as the other animals, birds and the thousands of soccer betters to get their predictions right. When throwing a set of three dices, the chance of getting a seemingly significant number such as 100, 666 or 911 is actually exactly the same as the chance of getting any arbitrary three-digit number such as 847.

Coming soon: Biases leading to beliefs

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