1. A system configured to reduce power consumption by overriding an instruction to measure affective response to content, comprising: a hardware-based mode-selector configured to receive first and second tags corresponding to first and second segments of content, respectively; wherein the first and second tags indicate to operate a device in a first mode of operation to measure affective response to the first and second segments; and a threshold module configured to receive first and second measurements of a user taken by a sensor before end of exposure of the user to the first and second segments, respectively; wherein the threshold module is further configured to determine that the first measurement reaches a first predetermined threshold; the threshold module is further configured to determine that the second measurement does not reach a second predetermined threshold, and to indicate said determination thereof to the hardware-based mode-selector; and the hardware-based mode-selector is further configured to: operate the device in the first mode of operation to measure affective response of the user to the first segment, and to override first mode of operation indicated by the second tag, by operating the device in a second mode of operation to measure affective response of the user to the second segment; wherein power consumption of the device when operating in the second mode of operation is at least 50% lower than the power consumption of the device when operating in the first mode of operation.