Final answer:
The cocktail party effect exemplifies selective attention, the process of focusing on a particular stimulus while ignoring others, as shown in studies by Simons and Chabris.
Step-by-step explanation:
The cocktail party effect provides an example of selective attention. Selective attention is the ability to focus on one piece of information in the environment while ignoring others. This concept is well demonstrated in various studies, such as the one by Simons and Chabris (1999), where participants were asked to count basketball passes and often missed seeing a person in a gorilla suit walk through the scene. This phenomenon shows how our attention can be so focused that we become unaware of other stimuli that are not the primary focus of our attention, even when they are clearly visible. It contrasts with inattentional blindness, where a person fails to notice a visible object or event because attention is engaged elsewhere.