Final answer:
A memory's stability after encoding highly depends on factors like the method of encoding and storage decay. Long-term memory has an unlimited capacity for retention, while short-term memory is more susceptible to decay and interference. Appropriate effortful processing and making information meaningful can help improve memory stability.
Step-by-step explanation:
How stable a memory is once you encode it depends on several factors, including how well it was encoded, how it is stored, and what happens during retention. Initially, when encoding occurs through effortful processing, we need to pay attention and actively work with the information. For example, most people cannot recall specific details of a U.S. penny due to encoding failure; they've never encoded those details into long-term memory.
According to Hermann Ebbinghaus's research, after encoding, we quickly begin to lose the details of a memory. His forgetting curve showed that we lose about 50% of memorized information after 20 minutes, and 70% after 24 hours due to storage decay. However, once information reaches long-term memory (LTM), it can be retained indefinitely, as LTM capacity is believed to be unlimited.
In contrast, factors like memory trace decay and proactive interference significantly impact short-term memory retention. Effective encoding methods such as the self-reference effect can improve the stability of a memory by making it more meaningful and thereby easier to recall.