People Need a Few Seconds to Be Random

Behaving randomly can be advantageous: it prevents others from capitalizing on patterns in our behavior. Unfortunately, the consensus from sixty years of psychological research is that people cannot do so: when attempting to be random, people’s responses exhibit systematic patterns. Random phenomena, however, are not instantaneously random. They require sufficient time between observations (e.g. the weather) or for enough iterations of a randomizing process to have occurred (e.g. card shuffling). It is unknown whether human sequences can be random if afforded such delays. Here we show that a modest temporal separation between items can make human sequences indistinguishable from random ones. We carried out our own experiment (N = 54) and analyzed ten existing datasets with different production rates, response sets, and response modalities. We found that when the delay between items was between two and four seconds, differences between human and random sequences disappeared. Furthermore, by comparing sequences produced by the same participants at different speeds, we confirmed that when participants make an effort, the needed delay is independent of production rate, akin to the weather. Our results show that people are able to generate randomness, and within a few seconds, giving us an accessible protection against potential exploits.