Typically in a sentence, a subject (S) performs an action (V) to a recipient of the action (O). For example, I (Subject – Personal Pronoun) read (Verb) a book (Object).
When an object is a person, we use object pronouns. For example: I (Subject) see (Verb) him (Object)
When the subject and the object are the same, we need to use reflexive pronouns. For example, looking into a mirror, I would say: I (Subject) see (Verb) myself (Object). In this example, the object and the subject are the same. The object, thus, is reflexive. The sentence “I see me.” is incorrect. If someone else were to look at me, for example: He (Subject) sees (Verb) me (Object), then “me” is correct, as I am the object in this example, but I am not the subject of the sentence, executing the action (to see). If “He” (the subject) is also the object, then the sentence would need to be “He sees himself.”
When using the indefinite pronoun “one”, the object pronoun is also “one”, and the reflexive pronoun is “oneself”.
I missed the bus this morning, so I drove myself to work.
She is a new teacher, so she introduced herself to the class.
There was no tour guide, so we showed ourselves around.
Reflexive pronouns can also be moved to the end of the sentence, or immediately after the subject pronoun when wanting to put the emphasis back on the subject or the antecedent of the sentence. Even though the pronoun is the same (-self/-selves) it is no longer directly reflexive, as the object of the sentence, but it is intensive. (Intensive pronoun)
She herself did this painting.
There was no tour guide, so we toured the museum ourselves.
She baked the cake herself.
A good way to differentiate between the two is that intensive pronouns are can be placed either at the end of the sentence or immediately after the subject pronoun. They are not essential to convey a specific context or meaning in a sentence (“She herself did this painting.” and “She did this painting.” convey the same meaning, namely that she is the person who did the painting. Adding the intensive pronoun merely adds emphasis). A reflexive pronoun is usually placed after the verb and can change the meaning (and integrity) of a sentence entirely. It is essential to a sentence’s meaning and context. When removing a reflexive pronoun from a sentence, the sentence no longer makes sense. For example, “She sees herself.” means, she is looking at a reflection of herself. Removing “herself” from this sentence creates an entirely new sentence with a completely different meaning. “She sees.”, as in she is able to see. It does not specify what it is that she sees.