Conscious processes in automatic visual and auditory search /

Abstract

A series of experiments investigated automatic processing in visual and auditory search tasks using masking techniques. Processing load in terms of the number of possible targets in the test period was varied under conditions in which test stimuli mask onset asynchrony (test SOA) was systematically reduced in duration. In Experiment 1, subjects received 17-18 hours of search task practice requiring speeded judgments of target presence or absence, using a consistent mapping procedure with categorical differences between targets and distractors. Accuracy and RT performance after extensive practice generally satisfied the capacity criterion for automatic detection of flat curve slopes across processing load levels in both the visual and auditory tasks. Experiments 2A and 2B compared automatic target detection to detection of the presence or absence of any test stimuli and ability to identify the test stimuli by verbal report at test SOAs between 50 and 1 ms. Stimulus detection was more accurate than automatic target detection at shorter test SOAs. Report performance and target detection performance did not differ. All of the tasks were performed accurately at shorter test SOAs with auditory stimuli. In Experiment 3, a multiple same target positive trial condition was compared to the highly practiced single target positive trial condition at reduced test SOAs. Accuracy was better in the multiple same target condition, indicating activation additivity in automatic target detection. Results of these experiments suggest that automatic target detection in search tasks is a conscious process and that it requires cognitive resources in addition to those required for stimulus detection.