Storage

Chapter 8, Lecture 3

“So, despite the brain’s vast storage capacity, we do not store information as libraries store their books, in discrete, precise locations.” - David Myers

Storage: Retaining Information

Storage is at the heart of memory. Three stores of memory are shown below: Sensory Memory Working Memory

Encoding

Long-term Memory Events

Encoding Retrieval

Retrieval

Sensory Memory

Events Sensory Memory

Encoding

Working Memory

Encoding

Long-term Memory

Retrieval

Retrieval

Whole Report

Sperling (1960)

R G T F M Q L Z S

50 ms (1/20 second) “Recall” R T M Z (44% recall) The exposure time for the stimulus is so small that items cannot be rehearsed.

Partial Report S X T J R S P K Y

50 ms (1/20 second) Low Tone Medium Tone High Tone “Recall” J R S (100% recall) Sperling (1960) argued that sensory memory capacity was larger than what was originally thought.

Time Delay A D I N L V O G H

50 ms (1/20 second) Time Delay Low Tone Medium Tone “Recall” N _ _ (33% recall) High Tone

Sensory Memory

The longer the delay, the greater the memory loss.

80 60 40 20 0.15

0.30

0.50

Time (Seconds)

1.00

Sensory Memories

The duration of sensory memory varies for the different senses.

Iconic 0.5 sec. long Echoic 3-4 sec. long Hepatic < 1 sec. long

Working Memory

Events Sensory Memory

Encoding

Working Memory

Encoding

Long-term Memory

Retrieval

Retrieval

Working Memory

Working memory, the new name for short-term memory, has a limited capacity (7±2) and a short duration (20 seconds). Sir George Hamilton observed that he could accurately remember up to 7 beans thrown on the floor. If there were more beans, he guessed.

Capacity

The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for

Processing Information (1956).

Ready?

M U T G I K T L R S Y P You should be able to recall 7±2 letters.

George Miller

Chunking

The capacity of the working memory may be increased by “chunking.” F-B-I-T-W-A-C-I-A-I-B-M FBI TWA CIA IBM 4 chunks

Duration

Peterson and Peterson (1959) measured the duration of working memory by manipulating rehearsal.

CHJ MKT HIJ 547 547 544 541 … CH??

The duration of the working memory is about 20 sec.

Working Memory Duration

Long-Term Memory

Events Sensory Memory

Encoding

Working Memory

Encoding

Long-term Memory

Retrieval

Retrieval

Long-Term Memory

Essentially unlimited capacity store. The Clark’s nutcracker can locate 6,000 caches of buried pine seeds during winter and spring.

Memory Feats

Memory Stores

Feature Sensory Memory

Copy

Working Memory

Phonemic

LTM

Semantic Encoding Capacity Unlimited 7±2 Chunks Very Large Duration 0.25 sec.

20 sec.

Years

Storing Memories in the Brain

1. Loftus and Loftus (1980) reviewed previous research data showing, through brain stimulation, that memories were etched into the brain and found that only a handful of brain stimulated patients reported flashbacks.

2. Using rats, Lashley (1950) suggested that even after removing parts of the brain, the animals retain partial memory of the maze.

Synaptic Changes

In Aplysia, Kandel and Schwartz (1982) showed that serotonin release from neurons increased after conditioning.

Synaptic Changes

Long-Term Potentiation (LTP)

refers to synaptic enhancement after learning (Lynch, 2002). An increase in neurotransmitter release or receptors on the receiving neuron indicates strengthening of synapses.

Stress Hormones & Memory

Heightened emotions (stress-related or otherwise) make for stronger memories.

Flashbulb memories

are clear memories of emotionally significant moments or events

Beryl Benderly has described “flashbulb” memories this way: “It’s as if our nervous system takes a multimedia snapshot of the sounds, sights, smells, weather, emotional climate, even the body postures we experience at certain moments.”

In a sentence or two, write down your three most vivid memories…

The percentage of Duke students who had flashbulb recollections of each event: A car accident you were in or witnessed When you first met your college roommate Your high school graduation Your senior prom An early romantic experience A time you had to speak in front of an audience When you got your admissions letter from college The day President Reagan was shot in Washington Your first flight The moment you opened your SAT scores Your seventeenth birthday The last time you ate a holiday dinner at home Your first college class The first time your parents left you alone at home Your thirteenth birthday (85) (82) (81) (78) (77) (72) (65) (52) (40) (33) (30) (23) (21) (19) (12)

Storing Implicit & Explicit Memories

Explicit Memory

refers to facts and experiences that one can consciously know and declare.

Implicit memory

involves learning an action while the individual does not know or declare what she knows.

p. 343

Hippocampus

Hippocampus

– a neural center in the limbic system that processes explicit memories.

Anterograde Amnesia

After losing his hippocampus in surgery, patient Henry M. (HM) remembered everything before the operation but cannot make new memories. We call this

anterograde amnesia

.

Anterograde Amnesia (HM)

Memory Intact No New Memories Surgery

Different from

retrograde amnesia

, which is loss of memory from before an event or injury.

Implicit Memory

HM is unable to make new memories that are declarative (explicit), but he can form new memories that are procedural (implicit).

A B C

HM learned the Tower of Hanoi (game) after his surgery. Each time he plays it, he is unable to remember the fact that he has already played the game.

Cerebellum

Cerebellum

– a neural center in the hindbrain that processes implicit memories.

Homework

Read p.345-349

“

At any given moment, we can consciously process only a very limited amount of information

.” - David Myers