This talk by Kevin Larson at the MIX10 conference (applicable part starts at ~ 69:00) has some great stuff about the cognitive and emotional impact of good typography.

You might be familiar with the 'candle test' -- high monetary incentives induce better performance on mechanical tasks but significantly *worse* performance on creative tasks. Using a variant of that experiment they found that reading speed and comprehension were unaffected by type and layout, but people's mood and cognitive reserve were noticeably improved by the good typography.

I suspect this doesn't say as much about type as it does about school -- that the bad typography, by slowing down reading, improves rote mechanical recall; and that if they tested for synthesis and creativity, good typography would out-perform bad.