Yes, the tatistascope (or whatever the name is), I remember that
one from I think grade school or thereabouts. Main reason I remember is
that I actually scared the hell out of my teacher, and was briefly
accused of cheating.

They erected the 'scope in the classroom, and showed one word at a
time, going from small one-syllable words then increasing. They flashed
the words in increasingly briefer intervals, two seconds, one second, a
half a second...fewer and fewer people were able to keep up. I got all
the way through to the highest the machine could handle, 1/12th of a
second, or therabouts.

Next the teacher started going into combinations of words, two or
three at a time. People started dropping out faster. Again, I stuck
with it to the end. The teacher began to wonder what the hell was going
on. (This was at a time when I'd learned that if you acted smart, you
got beat up, so I was deliberatly holding back on my grades and tests to
skate through in the middle ranks.) But here I kinda figured it was a
game, and didn't equate it. So I just went on to see how far I could
push it.

She kept expanding the length of the sentence. I was finally able
to hit 2 and 1/2 lines at 1/12th of a second before she stopped and
said I was to stay after class. I was accused (in front of the vice
principal) of cheating, having looked at the sheets of lines somehow,
because this was at or above college level ability. The vice principal
at first wouldn't believe me, but I finally managed to convince him to
pick other material and I'd try again. Reluctantly, he did it, going
right to the full-sentence stuff.

Same result. And the look on the teacher's face as she realized I
wasn't cheating was quite...remarkable.

Oddly enough, this has served me in small ways lately. Sometimes
in the later stages of post-production, when the final print has been
assembled by the super-computer, every so often a glitch will happen
and one random or wrong frame will get stuck somewhere, or you'll have
a single frame of black between a CGI sequence and a live-action
sequence. We're talking here 1/24th of a second. I almost always
catch these. I did this once during one of our audio mixes and the
guys running the board couldn't believe it, and ran the film back to
make sure I wasn't messing with them.

jms