I heard this in a documentary. The speaker is some serial killer who claims he started his rampage after watching a video.

He goes like this:

"I put one of the videos in and what came on the screen just shocked me. I coulnd't believe what I was seeing. That video triggered a memmory that I blocked out of me being a little kid. The switch went on and that was it."

Does he mean he turned on the tv and that was it OR is it some kind of idiom? What does he mean by that?

  • I think it's a somewhat clumsy usage. What the writer means is he had a "repressed memory" that suddenly became consciously accessible to him. Figuratively, I suspect he's suggesting he could "see" it because the light switch was turned on, but we wouldn't normally use that level of indirection. The blinkers came off, for example, makes a more direct reference to suddenly becoming aware of something previously "hidden". Turning on a "powered down" memory circuit in one's brain is credible, but not exactly a common usage. Commented Jun 24, 2015 at 14:48
  • 2
    When one has a Eureka moment, a sudden revelation, it's common to say 'A light went on'. This is in the same vein (though do switches 'go on'?) Commented Jun 24, 2015 at 15:01

1 Answer 1


The phrase "to turn on" means to activate or make the state of something different than it was before in such a way that it did not have a certain property before the action, but once turned on it does. IT can also mean that a certain property is made to be no longer dormant.

For a light being turned on, this means that the property of light coming out of the light and the electrical current now flowing through the light is present but was not before. Before a light is "turned on" it doesn't emit light, but afterwards it does. For a chainsaw, the property of movement in the chain doesn't exist, but after it is "turned on" this property does.

The same thing goes for the serial killer's "switch [that] went on". This means that his desire to kill was "turned on" or activated at that moment. He realized his desire to be a serial killer. His "property" of desire for killer was nonexistent, or dormant, before he was "turned on," but after he was, it became active.

The video and TV, on the other hand, have already been turned on so it is not be referring to them.

  • From another website: I cooked steak and mushrooms for myself when I was seven. But it took me a while to get into it. I hated the smell of garlic and got to 19 and the switch went on. I’d help Mum and it went from there. So it means like "something shifted inside me?"
    – aytug2001
    Commented Jun 24, 2015 at 14:45
  • 1
    It can mean this, yes. In the two contexts you provided it does. Commented Jun 24, 2015 at 14:47
  • Reason for downvote? The answer isn't wrong. Commented Jun 24, 2015 at 14:52
  • Probably lack of explanation. Not from me: I don't think it deserves a downvote but that is probably why the person did and your answer could benefit from explaining why you conclude the way you do rather than turning on the video or the chainsaw.
    – Avon
    Commented Jun 24, 2015 at 14:55
  • it wasn't me, I upvoted :)
    – aytug2001
    Commented Jun 24, 2015 at 14:55

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