One task an author has--especially one who writes paranormal, fantasy, or speculative fiction--is to suspend disbelief. After all, if I'm going to write about shape shifters, mythological creatures, demons, and such, then I need to convince the reader accept these characters as real for the duration of the story.
As a ghostwriter, this involves puncturing holes in a client's story.
One project on which I'm working involves a trek through an extensive subterranean network of caves and a supernatural creature. The progress of the protagonists immediately fell prey to a distinct lack of realism. There is where my background of knowing a little bit about a lot of things shows its value. With convincing arguments related to actual experience and a good bit of logic, the client agreed to some changes in his story to suspend readers' disbelief.
Failure to suspend disbelief affects movies, too. Poor graphic effects--see any fantasy movie from the 1970s or 1980s--instantly turn what could have been a great flick into a cheesy laughter magnet. This is a concept filmmakers George Lucas and Steven Spielberg understand. Vast improvements in CGI graphics help to make the transition from poorly conceived special effects to awe-inspiring admiration.
Steven Brust does this with his matter-of-fact descriptions of witchcraft and sorcery--not the same in his Vlad Taltos series. He speaks to the sensations of building spells and grabbing power, the emotional and physical feelings the magic user experiences. It's not necessary to own a grimoire or spellbook.
Anachronisms also crash the story. Characters acting in ways radically inconsistent with the norms of their class and time seldom fail to disappoint me. Actions and objects--even something as simple as donning a piece of clothing--that don't fit the occupation, conventions, or background of the character(s) also pull me out of the story. For instance, consider Azeem's use of a primitive telescope in the movie Robin Hood: Prince of Thieves. While it's a great scene imbued with wry humor, no such appliance had yet been invented at that time in history.
Suspension of disbelief not only concerns the environment in which characters find themselves and the special abilities they employ to defeat their enemies. It also concerns dialogue. Whether I'm reading historical fiction, a military thriller, romance, or fantasy, if the characters speak in ways that simply don't ring true, then that disconnect pulls me out of the story.
For an example, let's focus on romance. I've had sex. I have two children who are evidence of that. I cannot remember ever holding an extended and eloquent conversation with my husband during the process of procreation. Therefore, when I come across a scene of explicit intimacy in which the hero and heroine are holding a lengthy discussion, my mind automatically heads to the realm of "Hah! Not likely." In short, the author has failed to suspend my disbelief.
One hallmark of good writing is the ability to lure the reader into the story and immerse him or her into that world, only releasing the reader when the story ends or real life intrudes with its more urgent demands. Effective suspension of disbelief makes all things possible.