Can you analyze Robert Frost's "The Road Not Taken" using psychological criticism or a structuralism approach?

Robert Frost's “The Road Not Taken” presents a speaker who is forced to make a decision that he cannot really make—at least not with confidence.

Psychological criticism looks at literature by attempting to analyze it in terms of how the mind works. Often this is done with respect to the psychological theories of Sigmund Freud or Carl Jung. One of the most important aspects of Freud's theory was the importance of the subconscious and its effects on the behavior and development of the individual.

In “The Road Not Taken,” Frost uses the symbol (symbols are another key element of psychological analysis and development) of two diverging roads to look at the speaker's subconscious.

As the speaker looks at the roads, trying to decide which to take, he says,

. . . long I stood

and looked down one as far as I could

to where it bent in the undergrowth.

Difficult choices are common, and by themselves they are not always the subject of intense psychological study. At this point in the poem, the speaker is weighing his options and trying to decide, but there is not any intense psychological activity evident, at least not much below the surface.

This begins to change with the next stanza. The narrator examines one road, and we would expect to hear him say he then examined the other, but instead he just takes the other road. Why? Well, a clue might be found in the first road's description. It “bent into the undergrowth,” probably meaning it became difficult to see where it led. Fear of the unknown is a common psychological phenomenon, and there is good reason for it. The speaker's motives may be something else. Here is how he explains his choice to take the second road:

Because it was grassy and wanted wear;

Though as for that the passing there

Had worn them really about the same.

At first, the narrator is saying he chose the second road because it appeared to be less traveled, which seems an odd reason since he has already demonstrated potential fear over the first road's uncertainty. He then begins to reveal confusion over the whole matter when he reverses himself and says the roads are actually about the same.

The implication in all of this is that the speaker does not understand his own motivations and desires. It is hard for him to decide, and when he does, it is hard to justify the decision he makes. He seems to have made an impetuous decision, one he is apparently powerless to change, suggesting a strong degree of subconscious activity in this decision-making process.

In the final stanza, we see the speaker immediately regrets his decision:

I shall be telling this with a sigh,

somewhere ages and ages hence.

The “sigh” indicates he is already agonizing over his decision and projecting that unhappiness to a point later in life, suggesting (but not proving) a possibly neurotic difficulty in taking decisive action and being satisfied with it.

Frost is looking at the psychological difficulty experienced by the speaker in the face of a life-altering decision. Some of us have more trouble with these types of decisions than other people do. The role of the subconscious and the effect of neurotic conditions can make them even more problematic. This doesn't mean that just because you have a hard time making a decision, or just because you regret a decision, that you have a psychological problem—these issues are common to all human beings to some extent.