Lockhart's levels of processing theory suggests that memory retention depends on the depth of processing information undergoes. Shallow processing involves basic features, like the appearance of words, while deep processing focuses on meaning and connections, leading to better recall. According to this theory, deeper levels of processing create more durable memory traces. For example, when someone relates new information to personal experiences or existing knowledge, they are more likely to remember it later. This theory emphasizes that how we process information is crucial for effective learning and memory retention.