"Most of the characters in The Great Gatsby are involved in deception or self deception depending on their perception of what constitutes reality."
Now what is the perception of what constitutes reality in referrence to the above statement for Gatsby, Daisy, Tom, Myrtle and Meyer Wolfsheim?
F. Scott Fitzgerald's novel The Great Gatsby is at times a snapshot of The Jazz Age, and, as such the characters reflect the dissolute and the disembling of this era. In many ways, they have chosen to create their own realities, much as people of modern times do.
Gatsby is certainly involved in both deception and self-deception as he displays his new wealth in material possessions and evening gayla with friends whose names he does not know. Yet, he himself is deceived in his pursuance of an illusionary "American Dream" of wealth and love, both of which prove false. Daisy, whose voice "sounds like money" is impressed with this many colored shirts and his car, but vacillates in her profession of love for him. But, Gatsby, who does have real books inside the leather covers in his library, as Owl Eyes has discovered, is basically genuine; he chooses the deceptive life in order to reach the illusionary green light at the end of Daisy's pier, in order to attain her.
Daisy, like her name appears pure and sweet in her white dresses that mirror the flower whose name she bears. Yet, as the "golden girl" and one who loves money and is materialistic and shallow, she is much like the center of her flower--yellow, the color of corruption and gold.
Tom Buchanan involves himself with deceiving Mrytle Wilson into believing that he actually cares for her and thinks of her as an equal, but when she dares to criticize his class, he blackens her eye. He attempts to deceive his wife with this tryst with Mrytle, of course, while adding to his deception of others by dressing like the country gentleman in riding attire. Perhaps, his most villainous deception is that of leading Mrytle's husband to believe that Gatsby has driven "the death car." Tom's concept of reality is that it can be manipulated by those who are most powerful, an idea he certainly suggests in his promotion of his own race to maintain control of society.
Meyer Wolfsheim's name indicates much about him. He is a predatory man who uses Gatsby to further his own wealth, caring nothing for the dreamy Jay Gatsby. As a foil to Gatsby who is loyal to Daisy, Woflsheim has no deceptions of honor or the like in his morally corrupt soul. His main deception is in his creation of a business that is outside the parameters of legitimacy and the real business world, but he knows himself and is wary of others. Wofsheim's perception of reality is at its most sordid; he is paranoid as he knows there are others wolves waiting to devour him. His cuff links, two molars, suggest this idea.
Concerning The Great Gatsby, you don't ask for an answer to the statement itself, but only for an explanation of what, "what constitutes reality," means, so I'll try to answer that for you.
In short, this refers to how the characters view or perceive reality; what reality is for them.
Gatsby perceives reality in an idealistic way. He puts Daisy on a pedestal and idealizes her. He also idealizes his relationship with her, and sees their relationship, their past, as something that can be recaptured. His perceptions are faulty, however: his reality is an illusion. Daisy is not perfect, their relationship was never as he saw it (Daisy never loved him as he loves her), and the past cannot be recaptured ever, but especially when the past as he sees it never existed in the first place.
This is Gatsby's reality. I'll leave the rest to you or other editors. In case you'd like a description of actual deception by the characters, I'll place an extra link below to when this question was previously answered.
Gatsby's deception lies in the fact that he is playing a pafrt. He has made enough money (ostensibly through his underground dealings and bootlegging) to pretend to belong to the same class of people that Tom and Daisy belong to. However, it is revealed at the end that Jay Gatz is a man of humble origins but great ambitions. He deceives himself into believing that if he can become a member of the upper class he will be able to win Daisy's love. So, once he gets his wealth, he goes on a campaign to bring her back into his life and then deceives himself into believing that she actually loves him,, that she will leave her husband for him,, that she cares about anything other than money and security. Gatsby's perception of reality, therefore, is one in which money is the most important aspect of life. That and social status which can be bought if one has enough monry.
Daisy's perception of reality is one of the sheltered woman who has married money because that is what is expected if her. She sees herself as the pretty girl (which is all she wants for her own daughter - to be beautiful and dumb) who deserves to be taken care of monetarily and to have any mistakes she makes (such as killing Myrtle) covered up my the liberal application of money. She deceives herself into believing that this lifestyle can somehow bring her happiness.
Tom's deception is one of power and control. He deceives himself into believing that he gets away with his affairs, and he believes that his money and his power are all that he will ever need. He sees the world as revolving around him and the fact that he does not suffer any lasting ill effects from the events of the novel seem to show that, for people like Tom, their perception of reality becomes their reality, sad though it may seem to the outside observer.
Myrtle deceives herself into believing that Tom actually loves her and will eventually tale her away to live in his rich world. He fuels that deception with the apartment in the city and the dog, but it is only a role that she will be allowed to play in secret. Although Tom is bothered by Myrtle's violent demise, he goes on with his marriage as though nothing happened and, we can assume, he will likely find another Myrtle dome day to fill that void that he needs of living a second life underneath his wife's willingly ignorant nose.
Meter Wolfsheim has the most logical and realistic perception of life. He knows that what he does is dangerous, he has seen people killed, he is aware of the need to be careful, and he takes as much care as possible. He shows his love to his friends while they are alive because all of us will one day die and it will not matter to the dead what we think about them after they are gone. while he exists in the underworld, he lives in a world that he has created for himself and he is constantly aware of the parameters that define that world and what he must do in order to keep it from falling down around him.