Smiling Language?

Over at her New York Times blog, Olivia Judson wonders out loud: "Do some languages contain an intrinsic bias towards pulling happy faces? In other words, do some languages predispose -- in a subtle way -- their speakers to be merrier than the speakers of other languages?" For example, when you say "eee" your mouth curls up like a smile, and when you "ooo" it curls down like a frown (hence why we say "cheese" while taking a photo). Anyway, she goes on to try to answer her own question:

As far as I can tell, no one has looked at this. (It doesn't mean no one has; it just means I haven't been able to find it.) But I did find a smidgen of evidence to suggest the idea's not crazy. A set of experiments investigating the effects of facial movements on mood used different vowel sounds as a stealthy way to get people to pull different faces. (The idea was to avoid people realizing they were being made to scowl or smile.) The results showed that if you read aloud a passage full of vowels that make you scowl -- the German vowel sound ü, for example -- you're likely to find yourself in a worse mood than if you read a story similar in content but without any instances of ü. Similarly, saying ü over and over again generates more feelings of ill will than repeating a or o.