Book 1.indb

The term attention is typically used to refer to a set of processes that control the fl ow of information through the nervous system, modulating perceptual, motor, and response systems. One type of attention, termed selective attention, allows individuals to select specifi c objects in their environment for enhanced processing—a mechanism that is integral to successfully navigating a complex and dynamic environment. Selective attention for threatening stimuli is often referred to as an attentional bias toward threat, and may even be integral to the survival of a species, serving as the mechanism that allows for the quick assessment of potential sources of harm in the environment. For example, human beings who could more rapidly identify the arrival of a predator in the environment would have been better positioned to escape or more prepared to fi ght. Because an attentional bias toward threat should have increased odds of survival, the human brain may have evolved to preferentially process these stimuli (LeDoux, 1998). Nevertheless, attention toward threatening stimuli does not go unchecked—human beings possess large prefrontal cortices, which permit us to direct attention toward whatever stimuli in the environment are in line with ongoing priorities (Corbetta & Shulman, 2002; Semendeferi, Lu, Schenker, & Damasio, 2002). Therefore, recent research has questioned the extent to which threatening stimuli capture attention preferentially, especially when their processing is at odds with task demands.