Improving Vigilance Analysis Methodology

Abstract

We describe a vigilance experiment of a successive task and a simultaneous task. Successive tasks require comparing the current stimulus on the screen to a representation in memory (i.e. making a declarative memory retrieval), whereas simultaneous tasks require making a comparative judgment based on information that is available on the screen. When analyzing the data from this experiment using conventional methods, there was an effect of time-on-task (i.e. block), an effect of task type, and an interaction between block and task type. These findings were consistent with previously reported studies regarding the successive and simultaneous vigilance task distinction, which interpret such findings as evidence that the decrement is more severe for successive tasks. But different results and conclusions are made when more appropriate analyses of the data are used, such as: including block as an interval variable instead of a categorical variable and making the dependent variable detection of critical signals instead of using A’. When these analysis techniques were used, there was no effect of task type and there was no interaction with time on task. This raises questions about many of the findings in the literature, especially those regarding the successive and simultaneous distinction.