EXPRESS: Serendipity, strategy and psychic secretions: From general processes to individual differences

Pavlov observed that his dogs salivated not only when food was directly introduced into their mouths, but also when presented with other stimuli that had reliably co-occurred with food. This was a serendipitous observation. He called such cases of salivation psychic secretions or more prosaically conditional or conditioned responses. Our own research, born from a series of serendipitous interactions and findings, concerns reconciling general-process theories of associative learning with qualitative and quantitative individual differences in such conditioned behaviours; and in particular responses directed toward the conditioned stimulus (called sign-tracking) and those reflecting the unconditioned stimulus (called goal-tracking). The research is ongoing (i.e., incomplete), but has already prompted some revisions to received wisdom, including about the nature of associative structures involved, and the rules governing their acquisition and translation into behaviour.