Final answer:
Inattentional blindness happens when a person fails to see a visible object because their attention is focused on something else.
Step-by-step explanation:
Inattentional blindness happens when a person looks and fails to see a visible object. This phenomenon occurs when our attention is focused on something specific, causing us to miss other things in our visual field. For example, in a study where participants were asked to count the number of basketball passes, nearly half of the participants failed to notice a person dressed in a gorilla costume walking among the players.