Motion Detectors can be used to sense movements by often-unseen forces or spirits during investigations. If used correctly, and placed strategically, the investigator will know if something is moving in another room or from room to room, while the investigative team is elsewhere (but nearby)..
Motion detectors work well when left in a room during the time when no investigator is present, allowing the ghost to move more freely about the place. The detector has an alarm that sounds when movement is detected in the room or doorway where it is placed. The motion detectors are a big help when you are in a larger home or building. It gives the investigation team a broader area of coverage. Whenever the alarms go off, you can put additional monitoring equipment in that location.
Some motion detectors only turn a light on when motion is detected. They can be used in place of a chime or alarm-type sensor when an alarm sound is not desired. Investigators, however, need to ensure they are not setting off the unit themselves if investigating nearby. If working near any motion detectors, it may be a good idea to somehow make a boundary or line on the floor to act as a “do not cross” line.
Motion sensors that project an infrared beam are the most popular with ghost hunters. When the beam is disrupted by movement of any kind (natural or spirit), some sort of alert will sound so that the investigators can hear while away. This could be a good sign that spirit activity may be present where the motion detector resides.
Most motion sensors have an alarm mode and/or chime mode, where the chime mode will announce a movement. Chime mode setting is also less offensive and does not tend to scare investigators as much as an alarm.