Nielsen uses audimeters attached to television sets to continually record what channel the set is tuned to. This is an example of ________.

The observation can be done by two alternative procedures: human observation and mechanical observation. In human observation, a team of observers is used who, through physical procedures (visual and auditory), capture the information sought from the target group. On the contrary, observation is mechanical or electronic when carried out by more or less sophisticated devices.

At present, the complexity of some observations and the need for total objectivity in the observation processes make it necessary for human labor to be complemented and even substituted by the use of mechanisms or devices.

These mechanisms include:

The audiometer, which is a mechanical device that measures the time that a television is on, as well as the chain or chains that are connected (allows to determine the so-called share or screen share of each chain).
The eye camera, which records the route of the eyes and their fixation points on various surfaces, be it the computer screen, the sections of a newspaper, the pages of a magazine, a section of road, a shopping center or a billboard.
The psychogalvanometer is a mechanism that records changes in sweating associated with emotional reactions induced by stimuli such as advertisements or photos.
The hidden camera (or television in closed or open circuit), which serves to observe the reactions of the elements under investigation and in this way draw conclusions about their behavior before certain natural or artificial stimuli.
The pupilometer, which measures the changes that occur in the pupil size of the observed object. Thus, a rapid and appreciable change in the diameter of the pupil is usually a symptom of an emotional reaction to the stimulus presented.

In addition to these mechanisms, others could be cited as recording and digitizing devices for audio, photography, film and video; radars, sensors, scanners, photoelectric / infrared cells and traffic counters; voice tone analyzer; taquitoscopio, and counter of visits to websites.