In a SOC preparation, conditioning induced by CS1-US pairings is not assessed through re-exposure at test to the CS1. Instead, an additional set of pairings is conducted. These pairings comprise the original CS1 and a second, different neutral stimulus (CS2). This second stage (also known as second-order conditioning phase) is meant to allow the CS1 to transfer behavioral control to the CS2. If the learning experience is successful, the CS2 should now elicit a conditional response (Rescorla, 1980). The SOC procedure has been observed to permit expression of otherwise seemingly “silent” associations in developing organisms (Miller et al., 1990). This procedure might be particularly suited to assess ethanol conditioning in developing organisms as it involves functional capabilities known to be expressed early in life (see Molina et al., 2006). Specifically, developing rats encode stimuli of different sensory modality by taking into account their amodal properties, including their common affective properties (e.g., Spear & Molina, 1987). In other words, developing animals integrate, associate and functionally equate CSs of different sensory modalities and transfer motivational information between them (Kraebel & Spear, 2000; Molina et al., 1991).
