Effects of Intermittent Noise on Visual Search Tasks of Varying Complexity

Abstract

The present investigation was designed to test the effects of various ratios of intermittent noise on a visual search task varied in complexity. Four noise ratios were utilized: 0, 30, 70, and 100% noise on-time in successive 5-sec. intervals. The task required that Ss search a display for a single letter located among a larger background of letters which were all the same but different from the single letter. Task complexity was varied by changing the number of background letters. Two difficulty levels were utilized: 8-letter and 32-letter displays. Twenty-two Ss were tested under all conditions specified by the task complexity by noise ratio matrix. Detection speeds for the 32-letter task condition were faster for any ratio of noise than in the control condition but for the 8-letter condition only the 30% noise ratio was faster than the control. The speeds for the 70% and 100% ratios were slower for the 8-letter condition. The order of the 30, 70, and 100% ratios, however, without the control comparison indicated that the relative differences between noise effects were the same for both levels of task complexity. The order of conditions beginning with fastest was: 30%, 100%, and 70%.