Recent claims for the existence of extra-sensory perception (ESP) do not stand up to statistical analysis, says a new study.
Jeffrey Rouder from the University of Missouri in the US and Richard Morey from the University of Groningen in the Netherlands analyzed experiments by psychologist Daryl Bem of Cornell University, who claimed evidence for ESP.
Their application of a relatively new statistical method that quantifies how beliefs should change in light of data suggested that there is only modest evidence behind Bem's findings that people can feel, or sense, salient events in the future that could not otherwise be anticipated, and cannot be explained by chance alone.
Statistically, beliefs are odds, they say. For example, a skeptic might hold odds that ESP is a long shot at a million-to-one, while a believer might believe it is as possible as not (one-to-one odds).
According to Rouder and Morey, beliefs are odds. For example, a skeptic might hold odds that ESP is a long shot at a million-to-one, while a believer might believe it is as possible as not (one-to-one odds).
The researchers show that Bem's experiments indicate they should change by a factor of 40 in favor of ESP. The believer should now be 40-to-1 sure of ESP, while the skeptic should be 25000-to-1 sure against it.
They conclude that the skeptics odds are appropriate.
"We remain unconvinced of the viability of ESP. There is no plausible mechanism for it, and it seems contradicted by well-substantiated theories in both physics and biology. Against this background, a change in odds of 40 is negligible," they wrote.
The findings appear online in the Psychonomic Bulletin and Review.