The Effect Of Working Memory Load On Involuntary Attention

Many studies have started to address the interaction between working memory (WM) and selective attention. However, these studies mostly concerned with the voluntary or endogenous mechanisms of selective attention and little is known about the relationship between WM and involuntary attention. It would help us to understand the cognitive control mechanism of working memory through investigating the relationship between WM and involuntary attention. Therefore, the goal of the present study was to investigate how WM influenced involuntary attention by manipulating the WM load, In experiment one, in order to avoid the competition of perceptual attentional resource between WM task and selective attention task, verbal WM task and spatial position discrimination task was adopted to explore the influence of WM load to the distraction effect, which was produced by the "pop-out" red Korean. Results showed that the distraction effect was significant under high WM load condition and was not significant under low and middle WM load conditions. This indicated that the cognitive control resources was consumed by high load on WM and resulted in a failure of suppression of distraction, so the distraction effect was significant; while in the low and middle WM load conditions, subjects could assign resource to suppress the processing of distracters, so there was no distraction effect. This result supported for the load theory of selective attention.By experiment two, we used Event-related brain potentials (ERPs) to further investigated the electrophysiological effect of working memory (WM) load on involuntary attention caused by a task-irrelevant sound in an auditory-visual distraction paradigm. The different WM loads were manipulated by requiring subjects to remember the order of either three digits (Low-load condition) or seven digits (High-load condition), and the irrelevant auditory stimuli consisted of repetitive standard sounds (80%) and environmental novel sounds (20%). We found that the difference waves (novel minus standard) showed significant MMN and Novelty-P3 components in the two WM load conditions. The amplitude of MMN increased with increasing the WM load, which indicated a more engaged change detection process under High-load condition. Then, the amplitude of Novelty-P3 was attenuated under High-load condition, which indicated a much reduced involuntary orienting of attention to novel sounds when increasing the WM load. These results indicated that the top-down control of involuntary attention might be mainly active at the early change detection stage and the control of the later involuntary orienting of attention might be passive.Combining experiment one and two, we could conclude that WM did perform the "top-down" cognitive control function, but subjects also needed perceptual attention resource to complete WM task. Thus, high load on WM not only reduced the cognitive control resource, but also reduced the perceptual attention resource. Thus, the effect of WM load on selective attention depended on which resource was consumed much more or which resource was compete fiercer.