This study tested the validity of using facial electromyography (EMG) as a physiological measure of the valence of radio listeners' emotional responses to advertisements and explored the effects of message valence and listener arousal on attention and memory. A within-subjects experiment was conducted in which participants listened to ten 60-second radio advertisements that had been coded in a pretest as having either a positive or negative emotional tone. Facial EMG, heart rate, and skin conductance data were collected during exposure to the advertisements. Following exposure, participants completed free recall and recognition memory tests. Results demonstrated the validity of using facial EMG to assess the valence of emotional response to media messages. Heart rate data suggest that negative messages receive more attention than positive ones. Furthermore, how arousing a message is appears to be a better predictor of memory than message valence.