Attention is the cognitive process of selectively concentrating on one aspect of the environment while ignoring other things. Examples inclue listening carefully to what someone is saying while ignoring other conversations in a room (the cocktail party effect) or listening to a cell phone conversation while driving a car. Sometimes attention shifts to matters unrelated to the external environment, a phenomenon referred to as mind-wandering or "spontaneous thought". Attention is one of the most intensely studied topics within psychology and cognitive neuroscience.