What Is Semantic Role Labeling?

Semantic role labeling is the process of labeling parts of speech in a sentence in order to understand what they represent. Experts identify semantic role labeling as a natural language processing task, which means that its use brings technical analysis to examples of language. The use of this method can be helpful in determining how speakers of a certain language refer to subjects or other primary elements in a sentence.

Much of the focus of semantic role labeling is directed toward the verb or predicate of a sentence. Some of those who use this sort of technique define semantic role labeling as detecting “semantic arguments” that are connected to these parts of a sentence. Another way to explain this is that those who study this kind of labeling are considering what each word represents within the limited context of a sentence.

In order to clarify the methods and goals of semantic role labeling, researchers will often use clear labels to indicate the roles of words or phrases. For example, the words “agent” and “patient” may be assigned to two nouns in a sentence. This will help to show what is actually being referred to by a speaker or writer.

A basic example of this process will help beginners to understand how it is practiced. For example, in the sentence, “the hare beat the turtle in the race,” the hare is commonly understood to be the agent, and the turtle to be the patient. Taking the sentence the other way around and saying “The turtle was beaten by the hare” leads to the agent and patient relationship being switched, which will be differently labeled if these two sentences are compared to one another using semantic role labeling.

In the above example, it’s clear that this type of labeling helps to accurately define primary and secondary nouns in active and passive construction. In active construction, where the verb relates to the first noun in the sentence, the order of nouns determines which is the agent. In passive construction, this is not the case. This is just one reason why many instructors in an academic context tell writers to avoid passive construction in most cases.

Other efforts at semantic role labeling might show other relationships between nouns, verbs, or other parts of speech. These will generally help to clarify how grammar is used within a language. Examples of this type of labeling can help to provide a consistent definition for the role of a word or phrase.