Some attitudes are useful because they help to make the world more understandable. They help people ascribe causes to events and direct attention towards features of people or situations that are likely to be useful in making sense of them. Consequently, they help to make the world more understandable, predictable and ‘knowable’, as well as increasing the efficiency of information
Aidan Sammons psychlotron.org.uk

processing (cognitive economy). Stereotyping is an example of the knowledge function of attitudes. Stereotypes are mental structures that allow us to predict the characteristics a person will have based on the group they belong to. Using stereotypes to make sense of people is quick and requires minimal mental effort – both significant advantages in a complicated and fast-moving world. Of course, the down side of this type of thinking is that the inferences we make about people based on stereotypes may be unhelpful and wildly inaccurate.