Imagine if you will a world in which you are involuntarily subjected to what could be called a system of changing-your-mind control.

Imagine suddenly feeling pressured to leave a favorite gathering place not because you choose to obey the rules, but because a surreptitious little gizmo emitting a rather unbearable sound that only you and your peers can hear has been activated automatically and compels you to act accordingly.

You’ve entered to world, not of the Twilight Zone, but of Philadelphia Parks & Recreation. The city department has, for five years utilized a controversial, albeit commercially available, technology to discourage loitering, vandalism, or more serious criminal activity by driving away young people from certain locations between 10 p.m. and 6 a.m.

The department first deployed what’s called ’the Mosquito Device’ in 2014, and additional devices have since been installed at 30 park and rec locations citywide, the website billypenn.com reported. The devices cost $4,300 each to install, and only repel teens and young adults; youthful ears pick up the grating high-frequency sound, while those of older people typically don’t. The sound has been likened to the cringeworthy, if vintage, scrape of fingernails on blackboard, a whiny ringtone, a migraine headache, or other unpleasant sensations.

Reaction to recent news reports about what City Councilwoman Helen Gym calls “sonic weapons” has been loud and clear. “In a city that is trying to address gun violence and safe spaces for young people, how dare we come up with ideas that are funded by taxpayer dollars that turn young people away from the very places that were created for them?” Gym told NPR last week. Others have pointed out that bans on the technology have been called for in Scotland, and elsewhere criticized as enabling age-discrimination and assailed as a human rights violation.

Officials say the city has installed the devices largely at the request of local communities or members of City Council. Additional installation requests are still being received — last week, Councilman Bobby Henon told the Northeast Times that a Mosquito was soon to land at a playground in Tacony — but is now on hold, pending the outcome of a department review triggered by recent media coverage. A review is a good idea.

At first listen, there does seem to be a reasonable rationale for using a relatively low cost, largely imperceptible enforcement mechanism that avoids confrontation, helps promote public order, and protects public property. What’s so bad about that?

Nothing, really — were the purpose of the devices to repel actual mosquitoes or other pests. But despite being well-intentioned, effective, and even popular, these little machines are designed to repel human beings, a concept that for a parks and rec operation looks bad, sounds worse, and sends the wrong signal.

The devices influence human decision-making and human behavior in a way that would be deeply concerning even without the Twilight Zone optics. The Mosquito is intrusive and manipulative, a form of government-sanctioned behavior modification that’s fine for sci-fi but far from appropriate for a neighborhood pool or playground.