At the MobileHCI conference this year, I talked about my research into subliminal priming as a potential vehicle for behaviour change.
Subliminal priming is where you show someone a piece of information (the prime) that affects later judgements or actions despite them not being able to tell you what the information was. Unsurprisingly, the idea that things you can’t recall might affect you regardless inspires both moral panic (parents of 2 teenages who committed suicide sued Judas Priest for encouraging them to do so) and skepticism. It doesn’t help that the person that first claimed subliminal priming success from a movie theatre in the US in the 1950s turns out to have made it up as a publicity stunt :).
We carried out mutliple experiments, which together show that although you can use mobile phones (rather than fancy psychology lab equipment like tachistoscopes) to show masked subliminal primes. We used a technique called sandwich-masking, which sadly doesn’t involve actual sandwiches. You show a random pattern (a mask), then the prime, then the mask again, thus sandwiching the prime between two masks so that people have trouble consciously detecting the prime. We found that the “flash” transitions between prime and mask are clearly visible; and the results are mixed. So for mobile phones at least, the moral panic is unwarranted: people will know that something has happened, and it does not appear to have any stable effect on subsequent liking or selection of the prime.
The threat to your unconscious is unlikely therefore to come from subliminal priming on your mobile phone. But there are plenty of other things to worry about with technology trying to affect you oustide of your conscious attention…
You can read the full paper here.