Simultaneous activation of the representations of absent cues results in the formation of an excitatory association between them.

It is a common assumption of associative theories of learning that no change in the strength of an associative connection between 2 cues is possible in the absence of those cues. However, recently suggested modifications to associative theory (A. Dickinson & J., Burke 1996) have questioned this assumption by arguing that if the representations of 2 cues are simultaneously retrieved from memory, an association will be formed between them even though the cues themselves are not present. A flavor preference procedure was used to find evidence for such associations. In 3 experiments a novel excitatory connection was formed between the representations of peppermint and sucrose in their absence. This suggests that the assumption that cues cannot undergo a change of associative strength in their absence should be abandoned. The tension between the current results and accounts of mediated conditioning is discussed, and some suggestions regarding the difference between the 2 procedures are proposed.