Marketers often extend product lines by introducing slight variations of existing products (e.g., there are 53 varieties of Crest toothpaste, 15 varieties of Cheerios). As a result, consumers select from assortments containing relatively similar options. Unfortunately, consumers sometimes fail to differentiate among options, and instead consider the different options as similar and choose. Consequently, prior research shows that selecting from choice sets containing relatively similar options can sometimes lead to negative consequences such as decreased satisfaction. In light of these negative consequences, and given the frequency with which consumers choose from sets of similar options, it becomes important to identify interventions that can be used to optimize option differentiation (i.e., to optimize the perceived difference between two similar options or the perceived variety in an assortment). This dissertation proposes that incidental muscular sensations that consumers encounter while performing regular marketplace activities can serve as one such sensory based intervention. Drawing on theories related to learned associations and classical conditioning, it is proposed that because individuals experience high intensity muscular contractions concurrently with threat/danger, these muscular contractions and the responses they facilitate (i.e., self-protective reflexes) become linked. Through classical conditioning, high (vs. low) intensity incidental muscular sensations eventually activate self-protective reflexes in the absence of any threat or danger. Once activated, self-protective reflexes lead to increased perceptual sensitivity and discriminatory ability, and a sense of unconscious vigilance. Six studies show that the enhanced perceptual sensitivity and unconscious vigilance that result from high (vs. low) intensity muscular sensations optimize option differentiation, and can help to offset the decreased satisfaction that is sometimes associated with choosing from relatively similar options. Theoretical and managerial implications are discussed.