Topic 2.5 Notes – Storing Memories

Memory Storage Systems

Storage means retaining encoded information over time. A quick reminder of the full process helps here. Encoding gets information in, storage keeps it, and retrieval brings it back out later.

These memory systems differ in duration, capacity, and content.

Sensory memory

This is the immediate, super-brief storage of sensory input. It has large capacity, but most of it disappears unless you pay attention to it.

• Iconic memory is visual sensory memory. It lasts about 0.2 to 0.5 seconds.
• Echoic memory is auditory sensory memory. It lasts about 3 to 4 seconds.

That longer echoic memory helps you hear speech as one continuous stream instead of random sounds.

George Sperling’s partial-report study is the classic evidence. People saw a grid of letters too quickly to report all of them, but when told right after which row to report, they could give most of that row. In the figure, focus on the partial-report example with the cued row. That result showed brief, high-capacity iconic storage.

Sperling’s partial-report study

Short-term memory

Short-term memory is temporary conscious storage.

• Duration is about 15 to 30 seconds without rehearsal.
• Capacity is limited.
  • Classic idea: Miller’s 7 ± 2
  • More recent work often finds it’s closer to about 4 chunks

A chunk is a meaningful unit. For example, remembering 1 7 7 6 as “1776” uses chunking and saves space.

The Peterson and Peterson study showed how quickly short-term memory fades when rehearsal is blocked. Participants had to remember consonants while counting backward, and recall dropped fast.

Working memory

This is one of the most tested distinctions. Short-term memory is brief holding. Working memory is holding and using information.

Examples:

• doing mental math
• following multistep directions
• rearranging digits in your head

Baddeley and Hitch described working memory with parts:

• Central executive directs attention
• Phonological loop handles verbal and auditory information
• Visuospatial sketchpad handles visual and spatial information

Many diagrams also include the episodic buffer, which helps integrate information across the system.

Baddeley and Hitch’s working memory model

Long-term memory

Long-term memory is relatively permanent storage, from hours to a lifetime, with essentially unlimited capacity.

It includes:

• Semantic memory for facts and concepts
• Episodic memory for personal events
• Procedural memory for skills

This is not a literal file cabinet. Memories are spread across neural networks. The hippocampus is especially important for forming many new explicit long-term memories.

How Information Stays in Memory

Information often moves like this:

1. sensory input enters sensory memory
2. attention selects some of it
3. it enters short-term or working memory
4. if retained, it becomes long-term memory

Working memory also pulls stored knowledge back from long-term memory when you think.

Two biology ideas matter here:

• Long-term potentiation means repeated neural firing strengthens synaptic connections.
• Consolidation helps stabilize memories over time.

Stronger storage usually comes from meaningful processing, not just being exposed to something.

Rehearsal and Stronger Retention

Maintenance rehearsal

This is rote repetition. You repeat a phone number or code to keep it active.

It helps mostly with short-term retention. If no meaning is added, it is weaker for lasting long-term memory.

Elaborative rehearsal

This is much stronger for long-term storage. You connect new information to:

• prior knowledge
• meaning
• imagery
• examples
• categories
• personal experience

If a test question says someone explains, connects, visualizes, or personalizes information, that is elaborative rehearsal.

Autobiographical Memory and Exceptional Memory

Autobiographical memory

This is memory for your own life. It includes:

• episodic memories of events
• semantic knowledge about yourself

The self-reference effect means information tied to yourself is remembered especially well. That happens because self-related processing usually creates more elaboration.

Highly superior autobiographical memory

HSAM, or hyperthymesia, is exceptional recall for personal life events and dates.

Important limit: it does not mean perfect memory in every area. Research suggests biological contributions, but those findings usually come from case studies and correlational research, so they cannot prove cause and effect.

When Storage Is Impaired or Limited

Amnesia

Amnesia is major memory loss or inability to form memories.

• Retrograde amnesia is loss of memories from before injury.
• Anterograde amnesia is inability to form new long-term explicit memories after injury.

Patient H.M. (Henry Molaison) had hippocampal and medial temporal lobe damage. He could hold information briefly, but he could not form new explicit long-term memories. He still improved at mirror tracing, which showed procedural memory can stay intact.

Alzheimer’s disease

This is a progressive neurodegenerative disorder, not normal aging. Early damage often affects the hippocampus, so forming new episodic memories becomes difficult. Recent memories usually decline before older ones. Later, language, judgment, orientation, and daily functioning are affected.

Infantile amnesia

This is the inability of older children and adults to recall very early autobiographical episodes. Most adults have few true episodic memories from before about age 3.

This does not mean infants cannot learn. Likely causes include an immature hippocampus, limited language, and an undeveloped self-concept.