An information processing system includes an imaging device, a display, a memory, and a processor configured to acquire a customer ID for identifying a customer, generate a screen for the display for showing promotional content, control the imaging device to capture an image of the customer's face, then analyze the captured image to determine the degree of the customer's interest in the displayed content. The displayed promotional content is then stored in the memory in in association with the customer ID and the determined degree of the customer's interest.