Daryl J. Bem and computer security

In Feeling the Future: Experimental Evidence for Anomalous Retroactive Influences on Cognition and Affect (Journal of Personality and Social Psychology, DOI: 10.1037/a0021524), Daryl J. Bem presents his famous experiment:

This is an experiment that tests for ESP. It takes about 20 minutes and is run completely by computer. First you will answer a couple of brief questions. Then, on each trial of the experiment, pictures of two curtains will appear on the screen side by side. One of them has a picture behind it; the other has a blank wall behind it. Your task is to click on the curtain that you feel has the picture behind it. The curtain will then open, permitting you to see if you selected the correct curtain. There will be 36 trials in all. Several of the pictures contain explicit erotic images (e.g., couples engaged in nonviolent but explicit consensual sexual acts). If you object to seeing such images, you should not participate in this experiment.

In examining possible biases, he forgot one which is obvious to smart card operating system programmers. As a reminder, smart cards are security token subject to attacks because they contain money, or means to access power, for example, military or other places. One common attack thieves may use on smart cards is sensing the patterns of activation of the electronic circuits via equipment such as thermal sensors or electron beam probes. The most obvious example of defense, the first one taught to programmers, is that when writing in a program a "if" statement, the two sides of the statement should be of equal length, otherwise it is easy to know which side has been taken by measuring timing of electronic activation. Equal length is obtained by padding with bogus statements the side which would otherwise be smaller.

Typically, a non security-aware programmer doesn't know this, and would program Bem's experiment without regard to patterns of electronic activation. The computer would take a different path when priming for one kind of screen or the other, because it would associate the click instructions to one part of the computer circuitry or the other, which affects the internal pattern of the electronics in subtle ways, for example via caching algorithms of the operating system of the computer. It is entirely conceivable that a body primed for perception of erotic pictures via documented extra sensitization of the insula (How do you feel — now? The anterior insula and human awareness (A. D. (Bud) Craig, Nature Reviews Neuroscience 10, 59-70, January 2009)) would be capable of detecting the differential radiations, and therefore make accurate predictions; since the signal is very weak, it is also very understandable that the deviation from the norm would be small, as it is in the experiment.

Bertrand du Castel