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Researchers studying the topic of attention focus on the innerworkings of the brain and how it filters relevant information, or stimuli, within the environment. These stimuli encompass the entirety of all the information being gathered by our sensory organs and processing circuits (Gazzaniga, Irvy, & Mangun, 2018). However, a subset of attention, dubbed selective attention, focuses on how the brain chooses which information is relevant over which information is not. The study of selective attention has led researchers to another question, which is where within the information processing chain does selective attention actually take place. Two major trains of thought lead this debate, early selection and late selection (Gazzaniga, Irvy, & Mangun, 2018).

The early selection model suggests that stimuli within a person’s environment will be scanned early within the selection process. If this information is found relevant, it will be passed further along for processing, however, if it is not, it will be tossed out before in-depth information processing can take place. This idea is inline with Broadbent’s proposed model, where only important information is allowed to pass through bottlenecks, or choke points within the processing pathways, for processing, while less important information is stopped and ignored (Gazzaniga, Irvy, & Mangun, 2018). This can help explain situations like those proposed by the cocktail party effect. For example, when one is in a crowded environment, such as a concert, party, or another type of group gathering, they can choose to attend to a specific conversation while managing to ignore the other stimuli around them (Gazzaniga, Irvy, & Mangun, 2018). Utilizing the early selection model, the brain is made aware of the surrounding stimuli, via covert attention methods, but it is found irrelevant and thus is not processed unless it acts as a cue and catches the persons attention, such as a flash of light.

On the other hand, the late selection model suggests quite the opposite. Late selection models suggest that all information within the user’s sensory field is initially processed equally by the thalamus and other associated parts of the brain. Not until later in the processing stages is information determined to be important, encoded within memory, and acted upon (Gazzaniga, Irvy, & Mangun, 2018). This model suggests that a person will only act upon a stimulus when it is fully processed and recorded by the brain and a meaning has been established. This specific flow of information can be seen as a top down, goal driven, well informed behavior process (Gazzaniga, Irvy, & Mangun, 2018). For example, a person can take in all physical features, sounds, movements, and location of a creature moving up from a river, before actually determining that they need to run from an alligator.