The term valence can refer to either the affective response (e.g., "I feel bad") or the semantic knowledge about a stimulus (e.g., "car accidents are bad"). Accordingly, the content of self-reports can be more "experience-near" and proxy to the mental state of affective feelings, or, alternatively, involve nonexperiential semantic knowledge. In this work we compared three experimental protocol instructions: feelings-focused self-reports that encourage participants to report their feelings (but not knowledge); knowledge-focused self-reports that encourage participants to report about semantic knowledge (and not feelings); and "feelings-naïve", in which participants were asked to report their feelings but are not explicitly presented with the distinction between feelings and knowledge. We compared the ability of the three types of self-report data to predict facial electromyography, heart rate, and electrodermal changes in response to affective stimuli. The relationship between self-reports and both physiological signal intensity and signal discriminability were examined. The results showed a consistent advantage for feelings-focused over knowledge-focused instructions in prediction of physiological response with feelings-naïve instructions falling in between. The results support the theoretical distinction between affective and semantic representations of valence and the validity of feelings-focused and knowledge-focused self-report instructions. (PsycInfo Database Record (c) 2020 APA, all rights reserved).