Which symptom represents a decrease in emotional expression and is commonly associated with schizophrenia?

The symptom that represents a decrease in emotional expression and is commonly associated with schizophrenia is known as flat affect. Individuals with flat affect exhibit a diminished range of emotional expression; they may show little to no facial expression, have a monotone voice, and display a general absence of emotional responsiveness. This characteristic is significant in understanding schizophrenia, as it often affects interpersonal relationships and the individual's ability to convey emotions, which can contribute to social withdrawal and difficulties in effective communication.

In contrast, disorganized thought refers to a disrupted or incoherent form of thinking, which can manifest as nonsensical speech and difficulty organizing thoughts logically. Hallucinations involve perceiving things that are not present, such as hearing voices or seeing things that others do not. Delusions are false beliefs that are firmly held despite evidence to the contrary, such as beliefs of persecution or grandiosity. While these symptoms are also associated with schizophrenia, none directly represent a decrease in emotional expression like flat affect does.