What type of amnesia is characterized by an inability to form new memories?

Anterograde amnesia is characterized by the inability to form new memories following the onset of the condition, while memories formed prior to the incident may remain intact. This type of amnesia occurs when there is damage to areas of the brain that are crucial for encoding new information, such as the hippocampus. As a result, individuals with anterograde amnesia can recall past experiences but struggle to create or store new memories after the onset of their condition.

In contrast, retrograde amnesia involves the loss of pre-existing memories and affects an individual's ability to recall events that occurred before a particular incident or traumatic event. Post-traumatic amnesia is a type of memory impairment following a head injury or trauma, which may temporarily affect both retrograde and anterograde memory processes, but it specifically refers to the period of confusion and disorientation following the injury. Autobiographical amnesia, while not a widely recognized clinical term, generally refers to the inability to recall personal experiences and events from one’s life, which is a broader concept than the defined categories of amnesia.

Thus, anterograde amnesia is the specific type that corresponds to the inability to form new memories, making it the correct answer.