For example, you see a tree. You observe its size, the limb configuration, leaf shape, the color and texture of its bark. You see another tree, and another, and another. They are all different. If you don't place them in a category but have to think about each tree as a distinct individual with no relationship to any other, your mind would soon become overloaded with all the sensory impressions. Thus you sort the trees into categories by characteristics they have in common. It might be leaf shape: maple, oak, pine, willow. It might be by limb configuration: spreading, symmetrical. Overall they fit into the category of "tree".
This categorizing I call pigeonholing. A pigeonhole contains all the information you have gathered about any particular item or subject. This information is not only the direct impressions, such as might be gathered by any animal, from a slug to a dog. It also includes any extrasomatic input that is applicable to the item or subject. Your mind sorts all the information that comes in and puts it in an appropriate pigeonhole. Every time you perceive the characteristics of something, you place those characteristics in a pigeonhole. When you identify something else that has the same, or what you perceive as the same characteristics, it goes in that pigeonhole. Therefore the pigeonhole "tree" contains the general features of all trees. Thus, the next time you see a tree it opens the appropriate pigeonhole. You can identify it as a tree without having to devote much, if any thought to it.
You create new pigeonholes whenever new information that you deem important comes in. For example, specific information about trees becomes important: evergreen or deciduous, maple, oak, willow, etc. When you then see a tree you observe limb configuration, leaf shape, etc., and the new pigeonhole "maple tree" is called up rather than the pigeonhole "tree". If, however, you do not consider the new information important, no new pigeonhole is created; the old pigeonhole will suffice.
Something special about a particular tree, such as it being the one you climbed as a child or hit with your car, will create a new pigeonhole.
The above example of a tree is very simple. Most stereotypes are not. They consist of a gestalt of impressions, many of which are stereotypes in and of themselves. Not only are there the sensory impressions but the emotions, collateral impressions, what other people have told you the impressions are and mean, all the extrasomatic input about the subject. All go into the pigeonhole.
For example, you meet many people, some new to you and some old, every day. Each is a combination of facial features, coloration, size, shape, behavior, temperament, vocal characteristics, moods, etc. It would be impossible to carry all you know about each individual in your mind. Thus they are pigeonholed according to characteristics. There are pigeonholes for coloration (black, white, yellow, red), sex (male, female), size (tall, short, fat, thin), age (child, teen-ager, young, middle-aged, elderly). Let us say you have the following pigeonholes based on combinations of characteristics: white male, black female, short Asian, thin Indian, short fat black balding male with a bad temper and a lisp; tall fat white female with short hair, loud voice and a tattoo; tall slender young female with long blond hair; short, skinny, short-haired male with horn-rimmed glasses and a pocket protector.
You label these pigeonholes with stereotypes. The label may be "black man," or "California girl," or "nerd."
Why then does stereotyping have such a negative connotation?
People generally perceive that stereotypes mean all things with similar characteristics, whether those characteristics are significant or not, are exactly alike. They are "lacking in originality or individuality." For example, all blacks or whites (women, Asians) think and act alike because they have the same skin color (they are women or Asians). When someone sneezes they must have a cold or allergy, and a sizzling sound in the kitchen means a steak is being cooked.
This is the basis of preconception and prejudice. When someone or something triggers a pigeonhole because of many like characteristics, you expect everything in the pigeonhole to be true.
What becomes important is not the stereotype, but the contents of the pigeonhole the stereotype triggers. Pigeonhole contents come from two basic sources, primary and secondary. The primary source is the information you personally put into pigeonholes, your direct impressions. Secondary is the information you get from other people, indirect impressions. A major source of secondary information is family and friends. What they teach you as the way to view people, places and things is the way you do. For example, if your father is a member of the Ku Klux Klan, then you will have a certain set of information about blacks, Jews, Catholics, etc. The pigeonhole may say that blacks are lazy, smelly, ignorant, oversexed, or that Jews are power-hungry, money-mad, devious, unscrupulous. Thus when you see a black person, or meet a stranger and someone tells you he or she is Jewish, the stereotype label triggers the pigeonhole and all that information is what you think of about that person. Family and friends produce many other pigeonholes of this type, particularly when you are young: best car to drive, political and religious affiliations, hair length and clothing styles, views about schooling, government, blonds, brunettes and redheads, gender, beer, smoking, bill paying, everything. Again, stereotypes trigger them all. Primary information is what you gather yourself. The information in each pigeonhole is not only what others have taught you is in them, but what you put there yourself. This information could come from what you read, what you see, what you experience. If a young, long-haired, scruffy looking man mugged you, then the pigeonhole of young, long-haired, scruffy looking men will include that they will mug you. This stereotype leads you to fear such a man when you see one.
Difficulties arise from the relative importance an individual places on certain characteristics in a pigeonhole. Each person assigns a rank to each piece of information placed in a pigeonhole. The rank comes from their own preconceptions, prejudices, education and/or experience. For example, to some people gender or race ranks higher than ability. Thus, seeing a woman apply for a job would trigger the "woman" pigeonhole and ability would be subordinate to gender. To others, ability is more important that gender or race. (Point of interest: when I said "seeing a woman apply for a job would trigger the "woman" pigeonhole and ability would be subordinate to gender," did you automatically assume that it meant she would not get the job, or she would? Either would be a "stereotypical" response according to your own pigeonholing of the information triggered by the sentence. Both possibilities are true.) The problem is that many times people perceive the information in pigeonholes triggered by stereotypes as negative. They believe the information includes such falsehoods as Jews are money-grubbing, Blacks are lazy, women are emotionally unstable, men are insensitive; Russia is dark and cold and miserable, Detroit is grimy and crime-ridden, Los Angeles is smoggy and glitzy and phony.
Stereotypes are neither positive or negative simply because they are stereotypes. Many stereotypes are negative or positive depending on the person holding them. For example, a stereotype that women are better child rearers is positive to many people. However, to a father denied custody of his child by a judge who holds that stereotype of women thinks it is negative.