How can stereotyping effect us mentally?

Absolutely! Stereotypes are nothing more than the concrete, simplified conceptualization of groups. They arise out of grouping behaviors and traits into categories. When you observe a certain group of people behaving in a similar way, you create a category, or stereotype, for that group. This helps us understand and judge new experiences. We automatically use what we know already to better understand what is happening and to predict what may happen.

For example, you may have developed a stereotype for what a good employee is. This group probably includes people who dress professionally, perform the tasks asked of them, and have things prepared on time. If your boss then introduces you to a coworker, and mentions that they are a good employee, you use your stereotype to judge that individual. Therefore, you assume that this individual dresses professionally, performs the tasks asked of them, etc. etc.

It is important to remember that everyone develops their own unique stereotypes based on their own experiences. Although many people have similar ones, they always vary. And stereotypes are always changing. As we have new life experiences and evaluate said experiences with our stereotypes, we may find that we need to change or adjust the behaviors or traits that make up a certain stereotype. This means that stereotypes are plastic. We mainly use them to evaluate people or situations upon first glance. When we get to know someone or something better, we may not find it necessary to describe that person or thing by using categories. I suppose you could say that stereotypes provide us with quick and dirty information, based on our prior experiences.

It is also important to remember that stereotypes are NOT the same thing as prejudices. Prejudices are like stereotypes because they are also a type of category, however they are typically unreasonable, negative, and resistant to rational influence and change.