According to MIT researchers, the most difficult phrase to spit out is "pad kid poured curd pulled cod".
Trying to wrap your tongue around a phrase or short poem with repeated sounds is something that humans have been doing for centuries — at least that we know of: the practice probably goes back further than recorded history. We grew up giggling over tongue twisters like "Betty Botter bought a bit of butter" and "she sells sea shells by the sea shore" (and some more sweary variants).
Researchers at MIT now claim that they've conceived the most difficult tongue twister ever: "pad kid poured curd pulled cod". According to the lead researcher, psychologist Stefanie Shattuck-Hufnagel, it tripped up test subjects with high frequency — so much so that the team was offering a prize to anyone at last week's meeting of the Acoustical Society of America who could say the phrase 10 times quickly.
MIT isn't just studying tongue twisters for a laugh: Shattuck-Hufnagel studies speech errors as a way to understand normal brain function. "When things go wrong, that can tell you something about how the typical, error-free operation should go," she said. The team presented research wherein they had recorded volunteers speaking alliterative phrases, such as "top cop" and "toy boat", discovering that there were patterns in the way the speakers would stumble over the words.
This led to the creation of the "pad kid" tongue twister, which, to be honest, isn't really all that fun to say for the simple reason that it doesn't make a lot of sense.
We still think it has nothing on "The sixth sick sheik's sixth sheep's sick" or even "red leather, yellow leather".
You can see the full results of the team's research online at PubMed, titled "A comparison of speech errors elicited by sentences and alternating repetitive tongue twisters."