Help Strategies and Their Effect on Graphical Icon Usage
http://www.otal.umd.edu/SHORE/bs30/434-revised/index.html

McAlister, Britt and Chavi Greengart
SHORE
1997

Abstract:

An increasingly popular component of modern graphical human-computer interfaces are graphical command buttons. Studies have shown that graphical command buttons can enhance user productivity. However, two factors, the time required to acquire a working knowledge of the graphical command set and the need for frequent use to maintain the knowledge limit the effectiveness of graphical command buttons as a user interface strategy. This study attempts to quantify the effects of four types of help (balloon style, a mouse documentation line at the bottom of the screen, a help browser, and hardcopy documentation) on the ability of novice users to acquire a working knowledge of a graphical command set. The study did not find any significant difference (based on the anova and manova tests) between the four treatments.