When it comes to attention, early selection models of attention are defined by the textbook as “the idea that a stimulus could be selected for further processing or be tossed out as irrelevant before perceptual analysis of the stimulus is complete” (Gazzaniga et al., 2019, p. 284). In short, perception of the stimulus is not required prior to selecting its relevance. A filter might include the selection of relevant information from basic features, such as color, pitch, or direction of stimuli. An example of early selection models of attention could be Broadbent’s filter model. Donald Broadbent hypothesized that the information-processing system has “bottlenecks” in which sensory inputs are screened early through a sort of gating-mechanism, and only the most important stimuli will be processed, and the rest would be considered irrelevant and tossed out. One example of this may be the Cocktail Party Effect. At a party, there may be many people talking at once, including the person you are having a conversation with. Selective auditory attention enables you to participate in the conversation while ignoring the rest of the people talking around you. Through selective attention, one can perceive the signal of interest among other stimuli, and this would be considered a “top-down, goal-directed” system of attention.
Late selection models of attention are defined in the textbook as when the “perceptual system first processes all inputs equally and then selection takes place at higher stages of information processing that determine whether the stimuli gain access to awareness, are encoded in memory, or initiate a response” (Gazzaniga et al., 2019, p. 284). This suggests that stimuli are less selected based on physical characteristics, but instead on meaning. The unattended information is noticed but not passed into attention. This type of attention would be “bottom-up”. An example of late selection models of attention might be how a high school cafeteria likely has many students chatting at once. A person might catch a word or two from multiple other people, maybe someone’s name or gossip about your teacher, but the conscious attention is mostly with the person you’re conversing with across the table.
Overall, early selection mechanisms of attention influence the processing of sensory inputs before the completion of perceptual analysis, compared to late selection mechanisms of attention, which would only act after complete perceptual processing of the sensory inputs, at stages where the information had been recorded as a somatic or a categorical representation (Gazzaniga et al., 2019). Thank you for reading!