Hermann Ebbinghaus pioneered the experimental study of memory. His 'method of savings' measured how much faster a subject could relearn a list of nonsense syllables compared to the initial learning time, providing a quantitative way to assess memory retention over time.

The serial position effect demonstrates that people tend to remember the first items (primacy effect) and the last items (recency effect) of a list best. Items located in the middle are the most susceptible to interference and are therefore the most likely to be forgotten.

Psychological research indicates that traumatic events are often etched into memory with high vividness, making them highly accessible rather than easily forgotten. The concept of 'repressed' or 'suppressed' memories of trauma remains a subject of significant debate in clinical psychology, as empirical evidence often shows that trauma leads to intrusive recall rather than successful suppression or erasure of the memory trace.

Encoding is the initial process of transforming sensory input into a format that can be stored in the brain. It involves active processing, such as rehearsal or elaboration, which allows information to move from short-term or working memory into long-term memory. Without effective encoding, information cannot be successfully consolidated or later retrieved.

Selective attention is the process of focusing on a particular object in the environment for a certain period while simultaneously filtering out irrelevant stimuli. This cognitive mechanism allows individuals to concentrate on specific tasks despite the presence of distracting background noise or other competing sensory inputs.

Leading questions are generally avoided in investigative interviewing because they can contaminate a witness's memory by suggesting specific answers. Techniques like context reinstatement, changing perspective, and encouraging the witness to report everything are core components of the Cognitive Interview, which is designed to maximize memory retrieval without introducing bias or false information.

In standard psychological testing, recall, recognition, and relearning are the three primary methods used to measure retention. Reminiscence is often considered a phenomenon of memory recovery rather than a formal measurement technique. The source answer identifies 'Recall' as the correct option, which contradicts standard psychometric definitions of memory measurement.

Eidetic memory refers to the ability to recall images with high precision for a brief period after exposure. Research indicates that this ability is significantly more common in children than in adults, as it tends to decline as individuals develop more sophisticated verbal and conceptual memory strategies.

While chunking, overlearning, and meaningfulness are established mnemonic strategies that directly facilitate the encoding and retention of information, 'knowledge of results' is primarily a form of feedback used in motor learning and performance improvement. Although feedback can indirectly influence learning, it is not classified as a direct memory retention aid in the same cognitive sense as the other listed techniques.

The method of Loci is a mnemonic device that relies on spatial memory. By mentally placing items to be remembered in specific, familiar locations along a known route, an individual can retrieve the information by mentally 'walking' through that path. This technique leverages the brain's highly developed ability to recall spatial environments.