Everyone knows what a dog whistle is, dogs can hear it but humans can’t.

Recently, ‘dog-whistle politics’ has been in the news.

This is when only the people the message is intended for can hear it.

But to everyone else it seems perfectly harmless.

This gives the politician ‘plausible deniability’.

Whatever the hidden message, if it’s discovered they can pretend they didn’t mean it.

They didn’t even know it was there, they didn’t hear it.

An example of this is Donald Trump’s recent decision to hold an election rally on June 19th in Tulsa, Oklahoma.

He said he chose this date because it was when the proclamation of freedom for slaves was read in 1865 in Texas.

That’s the part that all humans can hear, fair enough.

But the dog-whistle part is that June 19th was also called Juneteenth by black Americans.

It’s the anniversary of the largest black massacre in America, and it happened in Tulsa.

Three hundred killed by a white mob, thirty-five city blocks burned to the ground, in 1921.

And it happened in the place where he was going to hold his rally: Tulsa, Oklahoma.

This is the part of the dog-whistle that only white supremacists can hear.

So Donald Trump could secretly tell his loyalist voters that he hadn’t gone soft, remember he’s still on their side.

But at the same time he has “plausible deniability”, he can say he only held the rally to mark freeing the slaves, anything else is the Democrats mischief making.

That’s dog-whistle politics.

Unfortunately for Donald Trump, there were some other people who could also hear that particular dog-whistle, black Americans.

So he was forced to change the date of the rally to the next day, June 20th.

Of course, one day doesn’t really change anything, Trump still sent a message to one group of people while pretending not to.

But dog-whistle thinking is something that could have interesting applications.

Technology now lets us address one group of people without anyone else even noticing.

A British company makes an Anti-Loitering Device.

It transmits annoying high-frequency sound on 17 kHz, which only people under 25 can hear.

This is used to stop gangs congregating in shopping areas, underpasses, car parks, anywhere they might cause problems.

So could dog-whistle thinking give us better targeting for advertising?

Well yes, but not in the way you’d hope.

A campaign for a Brazilian radio station was entered for the Cannes awards.

They claimed to play high frequency sounds under their music that would repel mosquitoes but remain inaudible to humans.

The campaign won the Cannes Grand Prix for Radio Advertising.

But Bert Knols, on the board of the Dutch Malaria Foundation, says they conducted ten tests and found it didn’t work at all.

Worse than that, if people believed it did work, they might start to rely on it and ignore genuine anti-mosquito measures.

Which would lead to many more deaths from malaria.

Winning awards has become our version of dog-whistle advertising.

Advertising that’s not done for ordinary people to hear.

Advertising that’s only done for other advertising people to hear.