The confessional poetic devices abound in this poem. The most evident one is the heavily personalized nature of the poem. This is accomplished through the first person narration throughout. It is also evident in the personal memories that the speaker experiences and shares with the reader. The "black shoe" which almost brings to mind the idea of living in a shoe box where definitions and parameters define one's state of being in the world without any freedom of expression is one such memory. Another one would be the inability to commuicate with the father, brought out in a visceral and powerful manner:
This is an example of the confessional nature because it takes the experience and brings it forth with the kind of physical imagery of "the moment" where conversation ceased. The confessional nature of the tongue lodged in the jaw does not escape the mind of the reader. One feels the discomfort of speech, the experience of pain in that instant. The closing of needing to "kill" daddy is something also confessional, in nature. I would think that the mere title is also confessional. The term "Daddy" indicates such a strong emotional connection, one where a child looks to the father in the most dependent of ways. The title of the poem is not "father," which is more clinical of a term. "Daddy" reflects that dependence of a child on its paternal figure, something that the speaker of the poem opens and closes with in terms of the patricide that needs to result. These examples of reflective of the naked sense of emotion that result in confessional poetry, the type of sensations that seek to bring about some form of catharsis and emotional revelation through poetic description. Certainly, the speaker, presumably Plath, seeks this end through the poem.
I would also say that the confessional poetry aspect is present in the overall purpose of the poem. At its very root, there is an unresolved relationship that exists between father and daughter. The poem is not clear as to what this relationship is, and in this ambiguity, is where the speaker/ Plath exists. In seeking to examine this relationship, Plath seeks to examine herself. This brings out another element of confessional poetry, in being able to use the poem to explore the more unsightly aspects of one's sense of being. This exploration and revelation, one that is done brazenly and openly, is where confessional poetry lies and is where Plath's "Daddy" also resides.