8. Memory: Models, Forgetting, and Constructive Processes

Memory: Models, Forgetting, and Constructive Processes

Memory Techniques and the Modal Model

Memory is a complex cognitive process involving the encoding, storage, and retrieval of information. One influential framework for understanding memory is the Modal Model, which divides memory into distinct stores.

• Modal Model of Memory: Proposes three main memory stores: Sensory Memory, Short-Term Memory (STM), and Long-Term Memory (LTM).

• Sensory Memory: Briefly holds sensory information (e.g., visual, auditory) for a fraction of a second.

• Short-Term Memory: Temporarily holds information for processing (typically 15–30 seconds).

• Long-Term Memory: Stores information over extended periods, potentially for a lifetime.

• Serial Position Curve: Demonstrates the primacy effect (better recall for items at the beginning of a list) and recency effect (better recall for items at the end).

• Is the Modal Model too simple? Evidence suggests memory is more complex, with multiple interacting systems.

Theories of Forgetting

Forgetting is a natural part of memory, and several theories attempt to explain why it occurs.

• Decay Theory: Suggests that memories fade over time if not accessed. However, research (e.g., Jenkins & Dallenbach) indicates that interference, not just time, plays a major role.

• Interference Theory: Proposes that forgetting occurs because other information interferes with retrieval.

  • Retroactive Interference: New learning disrupts recall of previously learned information.

  • Proactive Interference: Previously learned information interferes with learning new information.

• Encoding vs. Retrieval: Forgetting can result from failures at either the encoding or retrieval stage.

Example: If you learn a list of words before sleeping, you may remember them better than if you stay awake, due to reduced interference during sleep (Jenkins & Dallenbach experiment).

Amnesia and Types of Long-Term Memory Loss

Amnesia is a clinical condition characterized by severe memory loss. It can be classified by direction and source:

• Retrograde Amnesia: Loss of memories formed before the onset of amnesia.

• Anterograde Amnesia: Inability to form new long-term memories after the onset of amnesia.

• Organic Amnesia: Caused by physical damage to the brain (e.g., injury, disease).

• Functional Amnesia: Results from psychological factors (e.g., trauma).

Case Study Example: Patient N.C. could remember old memories and maintain short-term memory, but could not form new long-term memories (anterograde amnesia). However, some forms of learning, such as priming and procedural memory (e.g., mirror tracing), remained intact.

Types of Long-Term Memory

Long-term memory is not a single system but consists of multiple types:

• Explicit (Declarative) Memory: Conscious recollection of facts and events.

  • Episodic Memory: Memory for personal experiences (e.g., what you ate yesterday).

  • Semantic Memory: General knowledge and facts (e.g., cheese comes from cows).

• Implicit Memory: Unconscious memory for skills and procedures (e.g., riding a bike, making a burrito).

Additional info: Dissociations between explicit and implicit memory in amnesic patients provide evidence for multiple memory systems.

Memory as a Constructive Process

Memory is not a perfect recording of events. Instead, it is a reconstructive process, similar to perception, where memories are built from stored information and influenced by schemas and expectations.

• Constructive Memory: Memories can be altered or distorted by new information, suggestions, or expectations.

• Elizabeth Loftus (1975): Demonstrated that the way questions are framed can influence what people remember (e.g., asking about a barn in a video where none appeared led some participants to falsely remember seeing one).

Example: After watching a video, participants were more likely to "remember" seeing a barn if the question implied its presence.

Summary Table: Types of Long-Term Memory

Type	Description	Example
Explicit (Declarative)	Conscious recall of facts/events	Remembering your last birthday
Episodic	Personal experiences	Recalling a vacation
Semantic	General knowledge	Knowing Paris is the capital of France
Implicit (Nondeclarative)	Unconscious skills/procedures	Riding a bicycle
Procedural	Motor and cognitive skills	Typing on a keyboard

Key Takeaways

• Memory is not a unitary phenomenon; it consists of multiple systems and processes.

• Forgetting can result from decay, interference, or retrieval failures.

• Amnesia provides insight into the different types of memory and their neural bases.

• Memory is inherently constructive and subject to distortion.