According to general learning theory two major forms of learning can be observed across species. These universal forms of learning are classical and operant conditioning (Tarpy, 1997). Although both forms of conditioning can occur in the absence of awareness of the contingencies between CS (conditioned stimulus) and UCS (unconditioned stimulus) (or action – consequence contingencies) (Huston and Oitzl, 1989; Clark and Squire, 1998), close temporal proximity between a CS and a UCS is required to form an association. In other words, long-term association between a CS and a UCS (or an operant and its consequence) requires two distinct events to occur simultaneously or with little delay (in the range of ms) between them.