This eFile is about one of the fun things an author can do with their writing and mess with the reader’s mind. 
It’s called a “red herring,” a popular seafood dish served up with fried potatoes, but also good with crackers and a some Irish cheddar. However, that’s not what this is all about.
A red herring is some irrelevant information that diverts the reader‘s attention from the real issue. I remember a Charlie Chan movie where a number of people each have a motive for killing off their rich relative which is exploited by the writers. At the end the cast assembles in the sitting room and Mr. Chan goes from one to the other noting their motive and reason for not being the perpetrator until coming to the one most of the audience suspected least.
A red herring is a common device used in mystery and thriller stories to distract the reader from identifying the real culprit and keep guessing at the possibilities until the end.
This is also a favorite ploy of politicians wishing to dodge difficult questions. They do it by referring to a different issue, which of course is irrelevant, pulling attention away from the original issue under discussion. As long as authors don’t abuse their audience, they will love this tactic. So, how can it work? When dealing with characters, give selected players a reason or opportunity for being suspect.
Characters are not the only opportunity where to use this device. Setting has many variables to play with. Of course, there is the physical place, but also time – time of day, week, month. Then there is the weather. Is it hot, windy, rainy, snowy? Use multiple levels of detail.
Objects are another toy/tool – those that are present and those which are missing. I had the pleasure of helping teach a criminal investigation class and set up various crime scenes. There were items of significance and things designed to mislead or stall the investigation. The students also determined some evidence was missing. For instance, the victim has yellowed fingers from smoking. There is an ash tray, but no butts or ashes. There are peanut shells in the kitchen garbage, but the victim wears a warning on his wrist about a nut allergy. That may be significant or not as the victim likes to bake.
The more ways a reader can interpret a specific item, the more likely they will make a wrong assumption, and that’s exactly what the author wants to happen; however, a word of caution. Too many red herrings can frustrate the reader. And never, ever lie to them.
This discussion has focused on the mystery genre, but red herrings are successfully used in other genre. There are usually fewer of them with a different purpose. Instead of teasing the reader to incorrectly guess what has happened, the purpose is to have them guess what might or will happen, especially if the reader is privy to information the protagonist does not have. They will begin to speculate how that person will react when the surprise is sprung.
In one novel, the protagonist and antagonist literally cross swords. The antagonist is defeated, humiliated, and vanquished. Several years later, the hero is away helping a friend defeat a different villain. Unbeknownst to him the old enemy is now governor of the island where he lives. Being a prominent citizen and the island small, a meeting is unavoidable. The protagonist has tried to change his ways and mellowed out. How will the meeting go?
In another story, a young boy’s parents are murdered by the father’s brother, a major crime boss, so to acquire valuable property. The boy is to meet with an accident to complete the plan. The uncle is relentless, sending his most trusted henchman to find and finish the job, but time and again the boy escapes, often leaving the reader with the impression this is one very lucky lad. In the final scene, the vindictive uncle orders his henchman to finish the job and see the boy dead. Now, we learn how the boy has been so lucky. The henchman once loved the boy’s mother, but would not marry her because of his career, instead seeing that his best friend marry her. He was best man at the wedding and godfather to the boy that could have been his son. All along he secretly orchestrated the boy’s escapes from death, and in his last move to protect him, eliminates the last threat to his life. All along the way the use of red herrings diverted attention away from the godfather as being the boy’s guardian angel.
When reading stories, watch to see if the author introduces red herrings to divert attention from what is actually happening or will happen. If you like puzzle mysteries take a look at a master of the art, 
Agatha Christie, and see how she drops clues throughout the story, or go to YouTube and watch some Charlie Chan. Examples are all around and should become obvious as you are now aware of the technique.