Methods and systems are disclosed herein for determining whether a viewer watched an advertisement. In some embodiments, control circuitry generates for display an advertisement including a stimulus. For example, the stimulus may be incorporated into the advertisement by a content provider in order to trigger a region of the viewers brain. The control circuitry monitors brain activity in the region of the viewers brain during the advertisement. The control circuitry determines a brain state associated with the region based on the brain activity of the viewer during the advertisement. The control circuitry compares the brain state to a threshold range associated with the stimulus included in the advertisement. In response to determining that the brain state matches the threshold range, the control circuitry stores in a database an indication that the viewer watched the advertisement.
