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Chapter Summary
This chapter introduces the topic of attention. Despite James’s (1890) assumption that everyone knows what attention is, more than a century later the exact definition of attention eludes researchers. This is probably a result attention not referring to a single process but rather to a variety of pro-cesses and methods for studying the environment. Specific aspects of attention that are addressed in this chapter involve the selection of stimuli that we to attend to or ignore, involuntary attention, at-tempting to attend to more than one thing at a time, switching our attention between tasks, and the possibility of perceiving without attention or awareness.
As Broadbent demonstrated with his dichotic listening tasks, people have the ability to attend to important information, all the while ignoring irrelevant information (selective attention, cock-tail party phenomenon). His filter theory explained this aptitude by the fact that trivial information is prevented from being extensively processed (early selection). However, a debate arose when other experiments, such as the Stroop task, revealed the possibility of both irrelevant information being processed extensively (late selection) and even sometimes being perceived, and individuals actively ignoring irrelevant stimuli in order to process relevant ones. The Stroop task also brought up the debate regarding controlled (voluntary) versus automatic (involuntary) processes. Recent brain imaging studies have demonstrated the importance of the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC) as key areas involved in the selection of task-relevant material (DPLFC) and the detection of conflicting response tendencies (ACC), such as those seen in the Stroop task.
Spatial attention can be understood through a spotlight metaphor. The idea is that we can select to focus our attention on objects in our environment and this voluntary movement of attention is known as an endogenous shift and is typically studied using a central cueing paradigm. Some-times, contrary to one’s intentions, powerful or important stimuli can involuntarily grab people’s attention and this is known as attention capture or exogenous shifts; in other cases, individuals fail to attend to noticeable stimuli (inattentional blindness, déjà vu). Exogenous shifts of attention are studies using the peripheral cueing paradigm while other experimental paradigms (e.g., Flanker task) have shown that irrelevant information can be processed and affect behaviour. This raises the question of the limits to attention. Many different views of how our attention is limited have been offered. The capacity model views attention as a limited resource—like a “power supply”—that must be shared by concurrent tasks. Others view limits of attention as structural limits so that if two skills require the same kind of processing, they will interfere with attention more than if they had required different kinds of processing. Similarly, some view attentional limits as a central bottleneck that can process only one task at a time. There is also the view that people can simply develop the ability to pay attention to more than one thing at a time (divided attention). However, the average person generally has difficulty when performing dual tasks. The costs observed when completing dual tasks can also be observed when shifting mental resources from a task towards internal thoughts, a phenomenon referred to as mind wandering. Using the sustained attention to response task (SART) researchers have identified a default network of neural areas that are active when one’s mind is wandering (absorbed in internal thought).
The attentional blink (AB) refers to situations when the second of two targets that are present-ed close in time is not perceived. The task generally involves presenting a rapid serial visual presentation (RSVP) of items with two targets embedded at different points. Generally, people have difficulty identifying the second target if it is presented within half a second of the first target, although, the effect has been observed to diminish when listening to music, an area that deserves further research. Furthermore, the second target has also been observed to lead to unconscious priming effects, despite not being consciously reported.
Related to dual tasks, task switching describes how people perform more than one task con-currently by switching their attention from one task to other. This switching of attention can disrupt performance on tasks, which results in switch costs.
Another area of attention research involves the study of visual processes associated with attention and attention shifts. For instance, a contrast has been made between the act of attending to a stimulus by moving one’s eyes (overt attention) or without doing so (covert attention). There are several theories regarding these aspects of visual attention, such as the sequential attentional hypothesis. Overt attention, in particular, has been linked with reading performance and with the fixation of certain features in particular (eyes, mouth). The eyes move in specific ways and are capable of fixating on objects. The movements between fixations are called saccades. When fixating on a moving object, the eyes are using smooth pursuit movements. Knowledge possessed by the observer can help guide these eye movements when analyzing the environment.
Chapter Objectives
- To distinguish between theories of early and late attentional selection and review experimental evidence for each.
- To discuss endogenous and exogenous shifts of spatial attention and how attentional capture and inattentional blindness are complementary aspects of cognition.
- To review experimental studies investigating divided attention.
- To explain why mind wandering reduces attention to a primary task.
- To discuss the vigilance decrement and explain why performance on some tasks declines over time.
- To distinguish between covert and overt visual attention.