Failing to retain or to be able to recall what has been acquired is called:

Concept: Forgetting is the psychological term for the inability to retain or retrieve previously learned or acquired information over time — whether because the stored trace decays or is lost, or because it becomes inaccessible and cannot be retrieved even though some trace of it may remain. It is distinct from Memory (the overall system that encodes, stores, and retrieves information), Attention (the selective focusing on a stimulus that precedes and enables learning), and Imagination (the mental construction of images or ideas not tied to material already learned).

Application: The stem describes exactly this failure — being unable to retain or recall what has already been acquired. That is the textbook definition of forgetting: material once learned can no longer be retained in, or retrieved from, memory.

Contrast:

• Memory names the general system that encodes, stores, and retrieves information — the stem is asking about a specific event within that system (a failure to retain or recall), not the name of the system itself.

• Attention is the selective focus given to a stimulus at the point of learning — it concerns what gets noticed and encoded, not what happens to material after it has already been acquired.

• Imagination is the mental construction of images or ideas, which does not require anything to have been previously learned and later lost.

Result: A failure to retain or recall previously acquired material — whether due to loss of the stored trace or failure to retrieve it — is, by definition, forgetting.