The well-know Bernoulii's Theorem shows that the relative frequency of any random phenomenon tends towards its probability as the number of trials tends towards infinity. Thus relative frequencies depend on probabilities. Nevertheless, there are some phenomena the probability of which depend on the observed frequencies. For instance, those phenomena related with human memory. To see this fact, consider that to increase the probability of remembering some name, the most adequate strategy consists of repeating it. Thus, the greater the occurrence frequency of a name is, the greater is the probability of remembering it.