Since an inquiry about critical research of Hawthorne was also made, the student may wish to explore articles/ essays in such reference works as Critical Literary Criticisms. These volumes of analyses by professionals are accessible in public and college libraries. [cengage.com offers a trial subscription] Another excellent source of critiques on The Scarlet Letter are found in John C. Gerber's Twentieth Century Interpretations of "The Scarlet Letter." This is a collection of analyses of Hawthorne's work that is divided into essays on "Background," "Form," "Technique" and "Interpretations."

Under "Technique" there is an examination of Hawthorne's literary style which includes motifs of modern psychology conveyed through the use of allegory and symbolism. For, Hawthorne focuses more on a character's inner struggle than on developing that character's interactions with others, or even her/his confrontations with others, thereby providing the reader solely his own perspective of human nature. From these inner workings of his characters, S.L. and Y. G. Brown conclude that Hawthorne perceives human nature to be replete with wickedness as symbolized by Roger Chillingworth's increasingly depraved condition, his likeness to a fiend, and his digging up of the dark weed from the graveyard in his subjugation of his heart to his intellect. In like fashion, although her restrictions are not self-imposed, Hester's beauty fades, but it is because of her alienation and repressed condition wrought by Puritan justice and the wearing of the scarlet letter upon her bosom. For, when she casts it aside in her forest visit with the Reverend Dimmesdale, her hair regains it color, and her color and beauty return:

There played around her mouth, and beamed out of her eyes, a radiant and tender smile, that seemed gushing from the very heart of womanhood. A crimson flush was glowing on her cheek, that had been long so pale. Her sex, her youth, and the whole richness of her beauty, came back from what men call the irrevocable past....

So, too, is Dimmesdale's body affected by the torments of his mind and soul. Little Pearl, the incarnation and symbol of Hester's sin, like the psyches of her parents, cannot be whole until freed from their repressions.

She wanted [lacked]--what some people want throughout life--a grief that should deeply touch her, and thus humanize and make her capable of sympathy....

Indeed, Hawthorne's environment for characters is strictly controlled in order that he may present his unique perspective on the inner workings of their psyches. For, he develops his theme of the psychological danger of hypocrisy through this examination of the inner workings of his allegorical characters, proving that

No man, for any considerable period, can wear one face to himself and another to the multitude, without finally getting bewildered as to which may be the true.

Thus, by placing his characters in settings outside the ordinary, Hawthorne is able to explore the human consciousness using the techniques of allegory and symbolism.              

Additional Source:

Gerber, John C., ed. Twentieth Century Interpretations of “The Scarlet Letter.”Englewood Cliffs, N.J.: Prentice-Hall, 1968. 

The good news for you is that most of Nathaniel Hawthorne's major writings are quite similar in most literary senses; however, the final determination of your three points of comparison should obviously be based on which of his works you choose to use in your research. It seems to me that these three really strong points might suit any of Hawthorne's writings: theme, style and setting.

Theme is the central idea of any literary work, and Hawthorne uses some consistent themes in his work. One of those is alienation, as seen in "Rappaccini," Scarlet, and "Goodman Brown." For example, Rappaccini can only do what he does by physically alienating himself and his daughter from society, but the result for both the young people is also a kind of emotional isolation. Dimmesdale's conscience and guilt isolate him from his congregation and others, and Goodman Brown does his spiritual soul-searching alone in the forest one night.

Guilt, sin, and innocence are also common themes in his works. For example, Dimmesdale's guilt is overwhelming to the point of death, while Rappaccinni feels virtually no guilt for his heinous actions. Hawthorne also comments on the conflict between individuals and society in many of his works.

The most obvious overriding theme in all of these works is his depiction of unchanging human nature. In every time and in every setting, man's inherent nature is unchanging. Each of the characters in “Heidegger,” for example, has gotten older, but they have certainly not gotten wiser, demonstrated by the fact that when they have the unique opportunity to do things differently, they demonstrate the same character flaws as they did when they were young. Hawthorne is an astute observer of human nature, and his observations about it can be found in all his work.

Style is much easier to recognize and compare. Style refers to the way Hawthorne writes, and I’m certain you can already list several things which distinguish his writing from others, such as: long, complicated sentences; lots of figurative language; plenty of adjectives and adverbs; an abundance of details; and a distinct and rather high-level vocabulary. Examine three sentences from three of his works and you will see how similar they are.

And, with the final peal of that dreadful anthem, there came a sound, as if the roaring wind, the rushing streams, the howling beasts, and every other voice of the unconverted wilderness, were mingling and according with the voice of guilty man, in homage to the prince of all.

Before this ugly edifice, and between it and the wheel-track of the street, was a grass-plot, much overgrown with burdock, pig-weed, apple-peru, and such unsightly vegetation, which evidently found something congenial in the soil that had so early borne the black flower of civilized society, a prison.

There was one shrub in particular, set in a marble vase in the midst of the pool, that bore a profusion of purple blossoms, each of which had the lustre and richness of a gem; and the whole together made a show so resplendent that it seemed enough to illuminate the garden, even had there been no sunshine.

Setting is another aspect of Hawthorne’s work which lends itself to easy but effective comparison. He often uses a Puritan world, but he nearly always uses a rather ominous, Gothic setting for his stories, and elements in nature, in particular, are often responsible for the dark, rather mystical, and foreboding settings for his writings (see sentences above).