Intention, Response Selection, and Executive-Attention

Abstract

As we discussed in previous chapters, attention was considered to be linked to sensory and processes in most early cognitive theories. When we attend, some information is selected for further processing, and other information is ignored. Because attentional selection involves choosing one stimulus from a set of possible stimuli, it is easy to see why sensory selection has been emphasized in most theories of attention. However, attentional selection is also a "behavioral act," one that depends on motor activity or at least on response execution and control. As we attend to stimuli in our environment, we direct our focus by looking, orienting our bodies, or preparing to respond either overtly or covertly. Furthermore, response preparation and selection are effortful and are subject to fatigue. In this chapter , in fl uence of response selection and control on attention will be discussed. In early cognitive theories of selective attention, an attentional bottleneck was proposed. It was concluded that the bottleneck occurred at an early stage of processing, since attentional selection could be shown to occur even when there were no preexisting response demands or requirements for motoric action. For example, Broadbent [ 1 ] and Treisman [ 2-5 ] theories proposed a fi lter or a bottleneck soon after initial sensory registration. This type of bottleneck was thought to be necessary to explain the transition from parallel to serial processing by the amount of information competing for address in the central processing system. The bottleneck limited the amount of information to be handled during serial processing. A bottleneck is necessary because humans have dif fi culty performing multiple simultaneous tasks, especially when the tasks are demanding. By reducing the amount of information to be responded to at each point in time, the system can avoid being overloaded. The idea for such a fi lter mechanism was motivated by the observation that people typically can perform only a very limited number of activities simultaneously, and yet are exposed to a massive quantity of information at any given moment. As we discussed in the two previous chapters, subsequent research provided strong evidence that (1) attentional selection is possible and in fact often occurs at a very early stage of processing, even in the absence of preexisting response demands; and (2) people can perform more than one task simultaneously, as long as each task is not too cognitively demanding. Yet, peoples' capacity for performing concurrent tasks and for early attentional selection independent of response demands is dependent on many factors, including the nature and complexity of the stimuli to be processed and the tasks to be performed. Furthermore, this capacity varies as a function of individual differences across people.