Computerized assessment of sustained attention: a review of factors affecting vigilance performance. 
Results of empirical studies using computerized tests of sustained attention are summarized.  Factors that affect vigilance performance fall into three broad categories: task parameters, environmental or situational factors, and subject characteristics.  Complex interactions of factors from each category affect performance further.  Such interactions may help to explain inconsistencies in the literature regarding effects on vigilance.  Implications for both research and clinical practice are discussed.