Watchkeeping Performance as a Function of Certain Properties of the Viewing Situation

Abstract

Subjects performed a 90-min. watchkeeping task requiring the detection of a plus sign which occasionally appeared in a matrix of solid circles. Independent variables were: (1) number of stimulus elements in the display; (2) location of those elements relative to the strong contours produced by the physical boundary of the viewingfie1d;and (3) distance of the observer from the display. Average detection time for successive 100-trial blocks revealed the commonly observed vigilance decrement. Detection times were consistently shorter when a wider expanse of surround separated the stimulus array and the physical boundary of the display. They were not influenced by either stimulus density or viewing distance. ,Accuracy of response was found to deteriorate with an increase in stimulus density but was unaffected by the proximity of the display contours to the stimulus array or, again, by viewing distance.

The Neuroergonomics of Vigilance

“…Consistent with previous findings that spatial uncertainty degrades performance efficiency in vigilance tasks (Adams & Boulter, 1964;Baker, 1958;Bell et al, 1974;Grubb et al, 1995;Helton et al, 2010;Kulp & Alluisi, 1967;Milosevic, 1974;Mouloua & Parasuraman, 1995;Nicely & Miller, 1957), the overall level of signal detections in the present study was significantly lower among observers in the context of spatial uncertainty than in that of certainty.…”

“…Performance efficiency was poorer in the latter case. Adams and Boulter (1964); Baker (1958); Bell, Symington, and Bevan (1974); Grubb, Warm, Dember, and Berch (1995); Helton, Weil, Middlemiss, and Sawers (2010); Kulp and Alluisi (1967); Mouloua and Parasuraman (1995); and Nicely and Miller (1957) have also found that spatial uncertainty degrades the efficiency of signal detection in vigilance tasks. One issue that comes up in regard to these findings is whether they were actually related to uncertainty rather than just the need to perform a central versus noncentral task.…”

Signal Complexity, Response Complexity, and Signal Specification in Vigilance

“…A signilicant signal complexity by time interaction showed that differences between simple and complex signal groups increased statistically (p < .01) as time-on-task progressed. This result is somewhat consistent with expectations derived from past research (Adams and Boulter, 1964;Bell, Symington. Bevan, 1974; Brown and Fox, 1965;Goldstein, Johnston, and Howell, 1969;Could and Schaffer, 1967).…”

“…This in-sults a r e consistent with much previous terpretation seems to apply more to false research on task complexity where perceptual alarm rates than to correct detection percent-load increments have disrupted performance ages. (Adams and Boulter, 1964; Bell, Symington, The most pronounced differences in false and Bevan, 1974;Brown, 1963;Brown and alarm errors for specified and unspecified Fox, 1965;Conrad, 1955;Coldstein, Johnston, signal conditions occurred during the first 10 and Howell, 1969;Could and Schaffer. 1966; min of monitoring, although, as with the sig- Hawkes, Meighan, and Alluisi, 1964;Kidd and nal complexity variable, differences between Micocci, 1964).…”

“…Although a few studies have provided discrepant results (Alluisi and Hall, 1963; Could and Schaffer, 1967; Komaki, 1967; Wiener, Poock, and Steele, 1964), the most general finding, with regard to task complexity in monitoring performance, is that either pronounced decrements occur relative to simpler tasks (Adams and Boulter, 1964; Bell, Symington, and Bevan, 1974; Brown, 1963; Brown and Fox, 1965;Conrad, 1955; Goldstein, Johnston, and Howell, 1969; Could and Schaffer, 1966; Hawkes, Meighan, and Alluisi, 1964; Kidd and Micocci, 1964) or decrements are minimal or absent but overall performance is substantially reduced (Harris, 1966; Jerison and Wallis, 1957; Kennedy, 1971).…”