Buttons vs. menus
This exploratory study compares three command selection methods: pull-down menus, button bars, and user choice of pull-down menus or button bars. Results show that in frequently used functions, such as character attribute selection (bold, italic, underline, etc.), button bars are faster. There were no statistically significant differences in error rates between the three interaction methods. (Jul-05-98)
The link address is: http://hcil.cs.umd.edu/trs/95-06/95-06.html