ABSTRACT
This chapter represents an attempt to account for the problems some readers encounter when they process text on a visual display unit (VDU) rather than as hard copy. The people most likely to complain are typists and other professionals who use VDUs for long periods. The symptoms reported include eye strain, headache, minor visual disturbances, and fatigue. The exact nature of the disadvantage that the screen as a presentation medium may represent, still remains something of a mystery, but on the assumption that this disadvantage is real, computer and screen manufacturers have devoted a great deal of design effort to the search for the ideal display terminal. Unfortunately, this effort has been, so far, in vain. The main purpose of this chapter is to offer an explanation as to why this should be so.
