Dog
Dogs have served as home security systems since humans first constructed homes worth securing. The average dog can detect approaching visitors three to five minutes before doorbell activation, providing early warning through vocalisations that researchers classify as threat-proportionate alerting. Larger breeds present physical deterrence that security surveys indicate reduces burglary risk by up to 300 percent.
The psychological impact extends beyond mere detection. Intruders surveyed in prison studies consistently report that barking dogs represent their primary concern when selecting targets. A dog's presence signals unpredictability, potential physical confrontation, and certain noise that attracts neighbourhood attention.
Robot Vacuum
The robot vacuum provides no intentional security function whatsoever. It cannot distinguish between household members and intruders. It will clean around a burglar's feet with the same dedication it applies to family members. Its response to home invasion is continued floor maintenance.
However, some owners report that the unexpected activation of a robot vacuum in a dark room has startled delivery personnel and visitors to the point of elevated heart rate. This inadvertent psychological disruption provides security benefits its manufacturers never intended and would likely discourage consumers from relying upon.
VERDICT
Dogs provide millennia-proven security services. Robot vacuums provide floor cleaning that happens to occasionally startle pizza delivery drivers.