B.2.5.3. Discussion

These results were consistent with the idea that AC depended on both perceptual and cognitive load, in opposite ways (Lavie, 2005). Indeed, the AC increased from single task to dual task and from size-6 to size-3. First, this was consistent with the idea that increasing the perceptual load (through the number of distractors) left less perceptual resources available to process the irrelevant salient distractor, and thus decreased the AC. Second, this also supported the idea that loading executive WM (from single task to dual task) disrupted the ability to resist salience-induced interference, and thus increased the AC.

In this experiment, nothing was heard by the volunteers during the single task, whereas they had to listen to the list of digits in the dual task condition. The lack of noise in the single task was justified by the fact that noise could have adverse effects on attentional tasks (Dalton & Behm, 2007). Therefore, the distracting effects of the auditory list might have had to be resisted. According to the current hypothesis, this would have taxed WM, and thus have diminished the size of the expected effects. However, resisting the auditory list interference might reasonably be thought to require few WM resources. Consequently, and with that reservation, a second experiment was conducted in attempt to reject an interpretation referring to a simple perceptual effect. In this experiment, the subjects heard the same list of numbers in the single and dual task conditions, while only performing the digit detection task in the latter one.