Reactance
Etymology
Named by psychologist Jack Brehm in his 1966 book A Theory of Psychological Reactance. He borrowed "reactance" from physics — where it denotes a circuit’s opposition to a change in current — to describe a motivational push-back that arises specifically when a valued freedom is threatened or removed.
noun · /ree-AK-tuns/
The urge to do the opposite of what you’re told, triggered when a rule, warning, or pressure feels like a threat to your freedom to choose.
What it names
It explains why bans can boost demand, why "you can’t handle this" makes people try harder, and why heavy-handed persuasion so often backfires.
Example
The all-caps warning label produced pure reactance; sales of the banned edition doubled within a week.
Related idea
The backfire effect concerns beliefs hardening against contrary evidence; reactance is about freedom — the drive to reclaim an option someone tried to take away.
noun · /ree-AK-tuns/
In electronics, the opposition that inductors and capacitors present to an alternating current without dissipating energy as heat.
What it names
The part of an AC circuit’s total impedance that comes from storing and releasing energy in magnetic or electric fields, rather than from plain resistance.
Example
At higher frequencies the coil’s reactance rises, choking off the current.
Related idea
Reactance differs from ordinary resistance: a resistor turns current into heat, while a reactive component merely delays it and hands it back. Together the two make up a circuit’s impedance.