Cognitive blindness is the inability to understand something due to the lack of a precept of knowledge, understanding or belief in a necessary fundamental concept. Cognitive blindness can be a result of inadequate intellectual capacity for understanding something or it can be a result of emotional, cultural or cognitive biases.
The phenomenon can also be the result of a person being so focused one thing or perspective that they fail to see another perhaps otherwise obvious thing. One famous experiment that illustrates cognitive blindness was performed by Christopher Chabris and Daniel Simmons. The experiment was dubbed the invisible gorilla test.
The researchers had subjects watch a basketball game. Subjects were asked to keep track of the number of passes between players. The subjects’ given objective was merely a distraction. The real observation the researchers were curious to see if subjects made was of a man in a gorilla suit walking across the court. It might seem impossible to miss something so strange but more than 50% of subjects failed to see the gorilla at all.