Sind die Deutschen wegen der Umlaute in ihrer Sprache depressiv?
The BBC once claimed an American psychology professor had proved Germans are depressive because of umlauts.
Languagehat has also taken the story up, and there are comments.
Some seem to think the Turks should be even more depressive, but then they should be bipolar, since by the rules of vowel harmony a sequence of words will either have lots of umlauts or none.
Mark shows that there is a (very remote) basis for this story in psychological experiments on the relation of sounds and mood.
On the subject of confusing word pairs (drucken / drücken, schwul / schwül), I am afraid I have myself committed the solecism of saying, ‘Ich habe die Katze gefuttert’ (‘I ate the cat’).