Selective perception is a process by which one only perceives what he/she feels is right, completely ignoring the opposing viewpoints. In other words, he sees the picture only as he wishes to see, and not what the actual picture is. Many situations in real life attribute to this concept. Imagine, that you go to the supermarket to buy a few fruits, and you always pick up the ones you know taste good, having made this decision without tasting other fruits. You are told smoking is a bad habit, and before you even know a person, you label her/him as bad, because she/he smokes. You vote for a political party, only because it caters to your beliefs, irrespective of whether it contributes to any valuable changes in society. You overlook the fouls your favorite team makes in a game, because you are a devout follower of the team, and still hold the opposite team responsible for their own loss, or the loss of your favorite team.
All these are examples of selective perception that we humans are prone to making. Often termed as a cognitive bias in psychology, it is a process by which we filter out important information only to believe what we wish to believe. Our understanding of things develops through the number of events, people, or circumstances (known as stimuli) we have been exposed to. Our behavior (known as response) is then shaped based on these events and our experiences with these events. These experiences get etched in our memories so that our responses are similar to any situation or person that is only 'similar' and not the 'same'. We behave in accordance with our expectations of a person or a situation. This behavior can be understood by means of some more examples.
Let us consider a woman who is in an abusive marriage. Her husband is an alcoholic and picks fights on the most mundane issues. He has made her believe that it is for 'her good' that he behaves in this manner. She finds herself emotionally dependent on her husband. You as a friend try to convince her to get out of this abusive marriage by trying to show her the reality; her husband is a raging, abusive alcoholic and is completely dependent on it. Because he does not know how to deal with this habit, he is venting his anger and frustration on her. She, on the other hand, refuses to accept this truth. She claims she can change him, that there is a good side to him that she will eventually bring out. This is a clear case of selective perception, where the woman in question distorts the reality, fails to accept it, and perceives it in a manner that is suitable to her comfort (which may be financial or emotional dependence on her husband, or the mere comfort of having a man in her life). Unless a situation does not trigger a defense in her and present reality in a whole new light, it may seem to you that you are trying to get through a stone wall with nothing to actually aid you in your defense.
In the process of being exposed to a stimulus, registering it in our system, organizing our thoughts and feelings about the stimulus, and then interpreting it, the actual effect of the stimulus and the facts pertaining to it are distorted. All this makes us perceive the stimulus differently because of all the thought processes we have put it through. As such, the final output is expressed in terms of our response to the stimulus, and is based on what we want to and do not want to make of it. This becomes what is termed as selective perception.
This concept is often used as an advertising strategy to enhance the popularity and sales of a product. For instance, there is a great demand for a particular brand of a cell phone, which you then consider buying yourself. You suddenly see an ad for the same in the newspaper, a magazine, or on television. Suddenly, that phone is all over the place. What you don't notice is that all this has always been around you, but you have filtered out these stimuli, because you never really needed that cell phone. However, now that you are considering buying the cell phone, you are seeing it everywhere because your general awareness now includes the lookout for the cell phone. The company on the other hand, has created or triggered the desire in you to buy the phone by promoting the product to make it popular, thereby increasing your awareness about it.
As can be seen, there are numerous ways in which selective perception occurs in our lives. We tend to generalize, make stereotypical judgments, and fundamental attribution errors in the process too. In short, we tend to distort the truth in order to make ourselves feel good, to pacify our beliefs, and in some way, evade reality to be able to take decisions easily. It is a common practice and to actually consider all the stimuli we are exposed to, we will have to increase our overall awareness about these stimuli.