Today’s smartphone notification systems are incapable of determining whether a notification has been successfully perceived without explicit interaction from the user. If the system incorrectly assumes that a notification has not been perceived, it may repeat it redundantly, disrupting the user and others (e.g., phone ringing). Or, if it incorrectly assumes that a notification was perceived, and therefore fails to repeat it, the notification will be missed altogether (e.g., text message). Results from a laboratory study confirm, for the first time, that both vibrotactile and auditory smartphone notifications induce skin conductance responses (SCR), that the induced responses differ from that of arbitrary stimuli, and that they could be employed to predict perception of smartphone notifications after their presentation using wearable sensors.