Examples described herein enable “in situ” sensing, which collects and analyzes physiological responses from a large group of viewers/audiences who watch a same media instance together at a single venue. Each of the group of viewers is fitted with physiological sensors with communication capabilities to communicate with a signal collection device at or near the venue. The signal collection device collects the physiological data of the viewers from the sensors, and transmits the physiological data to a processing module at another location via a network for storage and further analysis.