Productivity and Multi-Screen Computer Displays 
One hundred eight university and non university personnel participated in a comparison of single monitor, multi-monitor and multi-monitor with Hydravision display configurations. Respondents edited slide shows, spreadsheets and text documents in a simulation of office work, using each of the display arrays. Performance measures, including task time, editing time, number of edits completed, and number of errors made and usability measures evaluating effectiveness, comfort, learning ease, time to productivity, quickness of recovery from mistakes, ease of task tracking, ability to maintain task focus and ease of movement among sources were combined into an overall evaluation of productivity. Multi-screens scored significantly higher on every measure.
Colvin, Janet, Nancy Tobler and James A. Anderson. Rocky Mountain Communication Review (2004). Articles>Human Computer Interaction>User Interface