[reading: Jón Árnason, Alan Boucher (translator), "Icelandic Folk Tales"]
One of the MindHacks that doesn't include an easy demonstration is Hack 39, where you're less likely to notice a trigger event if it occurs soon (say, <0.5s) after another trigger event.
My first attempt to test this out is below, but I have to say that the effect didn't seem all that strong to me—so maybe there's a bug or I've implemented it wrong. Or maybe I'm just too impatient to run it for long enough to get statistically significant data.
After hitting "Go", this applet will display letters for a tenth of a second each. You should hit a key whenever the letter displayed is either "X" or is displayed in white. To stop the applet, hit "Stop" or press the Escape key.
After running the applet, the bar graph shows the time between triggers (on the X axis) against how many triggers there were with that delay; the white is the total number shown, the black is the subset of them that were missed. Hitting "Go" again accumulates more data.
Technical Details: letters are picked uniformly (so there's a 1/26 chance of a letter X trigger) and white is used for the colour 1/20 of the time. A trigger is considered hit if there's a keypress within 1 second after the trigger, but each keypress only counts once (so "trigger, trigger, keypress, letters…" would count as one hit then one missed trigger, with a delay of 1).
[A:37385 B:3278 C:346 D:9187 E:46445 Total:96641]