Abstract: Methods and apparatus for determining preferences of persons viewing broadcast television programs on television display sets located in rooms of private homes humanly imperceptibly sense proximity of persons to television sets within viewing distance in rooms for which permission to effect such sensing has been obtained. Each such room may be electrically scanned for proximity of one or more persons to a television set. The imperceptibly sensed proximity or the proximity of persons detected by scanning is automatically correlated to television programs broadcast for display by television display sets in the above mentioned rooms and elsewhere, and there is electronically determined from that correlated sensing what broadcast television programs were viewed in which rooms and, optionally, by how many persons.