Thematic Roles

In syntax, we categorize nouns into subject, direct object, indirect object, and so on. Similarly, in semantics, we can classify nouns by their thematic roles in a sentence. Thematic roles describe participants’ (i.e., nouns’) relationships to each other and to the actions and events in a sentence. The major thematic roles are: agent, cause, experiencer, theme, instrument, location, and goal.

Examples

The woman chased the mouse out of the house with a broom.

• Woman: Agent
  An agent has self-awareness and willfully causes an event / performs an action.

• Mouse: Theme (Patient)
  A theme is the object of an event/action. When a theme is affected by an action and undergoes some sort of change, it is often called a patient.

• House: Location
  A location is a place where an event occurs.

• Broom: Instrument
  An instrument is used by an agent to accomplish an action.

The mouse was afraid of the cat.

• Mouse: Experiencer
  An experiencer is percieves something or experiences a mental state. They do not act on or alter the other nouns in the sentence.

• Cat: Cause
  A cause is something that causes something else to happen without agency or intention. Causes are often, but not necessarily, inanimate.

The boy gave some cheese to the mouse.

• Boy: Agent

• Cheese: Theme (Patient)

• Mouse: Goal
  A goal is something that receives a theme. It can be a person, place, or something else. With most ditransitive verbs, the indirect object is a goal.