Today’s smartphone notification systems are incapable of determining whether a notification has been successfully perceived without explicit interaction from the user. When the system incorrectly assumes that a notification has not been perceived, it may repeat it redundantly, disrupting the user (e.g., phone ringing). Or, when it assumes that a notification was perceived, and therefore fails to repeat it, the notification will be missed altogether (e.g., text message). We introduce SweatSponse, a feedback loop using skin conductance responses (SCR) to infer the perception of smartphone notifications just after their presentation. Early results from a laboratory study suggest that notifications induce SCR and that they could be used to better infer perception of smartphone notifications in real-time.