Chapter 5: STM and working memory

Question 1

What are the stages of Atkinson and Shiffrin’s “modal model of memory?

Answer 1

1. Sensory memory: Holds incoming input for fractions of a second
2. Short-term memory: Holds 5-7 items for 15-20 seconds.
3. Long term memory: Holds a large amount of info for up to a lifetime.

Question 2

What are “control processes” (described in A&S’s model)?

Answer 2

Examples:
- Rehearsal - used during STM stage, involves repeating stimulus over and over.

• Strategies of attention that help you focus on what is important (during sensory memory stage, so that it can be registered into STM)

Question 3

What is the persistence of vision?

Answer 3

Continued perception of a visual stimulus even after it ceases to exist (demonstrates sensory memory holds visual stimuli for a brief moment after it is perceived)

Question 4

What did Sperling’s experiment show about the capacity and duration of sensory memory?

Answer 4

Method + results:
- When ps were shown a brief display of 12 letters and asked to report AMAP, they were only able to report 4.5/12. However, ps said that this was not because they didn’t see all of the letters, but because by the time they got to later letters, they had faded from perception.

• When ps were asked to report only 1 row immediately after seeing stimuli, they were able to report 3.3/4.
  HOWEVER, when there was a 1 second delay between showing and indication of which line to report, ps were only able to report 1/4.
  ——————-
  Significance:
• All info must be registered, as ps are able to report one row if immediately asked.
• Duration must be shorter than 1 second, as reporting performance drops off rapidly.

Question 5

What is the duration of short-term memory? How can this be explained by proactive interference?

Answer 5

Duration: 15-20 seconds.

Proactive interference:
(Ps who were asked to report a series of letters after 18 seconds performed worse than those who reported after 3 seconds –> however, this was only the case in later trials - i.e. Ps who reported after 18 seconds on the first trial still performed highly!)

THEREFORE, it can be inferred that drop-off in memory can be explained by the fact that info learned in the past can affect learning of new info.

Question 6

What is retroactive interference?

Answer 6

When new learning interferes with remembering of old learning.

Question 7

How does digit span measure the capacity of STM?

Answer 7

Digit span - the number of digits a person can remember.

*Average capacity is 5-9 items (~a phone number)

Question 8

How does change detection measure the capacity of STM?

Answer 8

Experimental method: Two pics of a scene flashed one after another, ps needs to detect changes between pics.

• If there are <4 items in an image, ps can detect differences easily. However, any more than 4 items and performance decreases.

Question 9

How does chunking help increase the capacity of STM?

Answer 9

By collecting elements that are strongly associated with each other into meaningful units - increases capacity from 5-8 unrelated words to 20+ words!

Question 10

How does detail affect the number of items we can keep in STM?

Answer 10

The greater amount of info in an image (i.e. more detail), the fewer items can be held in STM.

Question 11

What is the difference between STM and working memory?

Answer 11

STM: Stores info for short periods of time

Working memory: MANIPULATES info that occurs during complex cognition (e.g. Remembering the first part of a sentence while processing a question)

Question 12

What are the components of working memory, as conceived by Baddeley?

Answer 12

1. Phonological loop: Holds verbal and auditory information
2. Visuospatial sketch pad: Holds visual and spatial info (e.g. Solving a puzzle, finding your way around campus)
3. Central executive: “Attention controller” - Retrieves info from LTM, coordinates activity between phonological loop and visuospatial sketch pad and divides attention between different parts of the task at hand (e.g. Take verbal directions while navigating your way to a restaurant in a car.)

Question 13

What are the components of the phonological loop?

Answer 13

1. Phonological store: Limited capacity, holds info for several seconds.
2. Articulatory rehearsal process: Rehearsal that keeps items in the phonological store from decaying (e.g. Repeating a phone number)

Question 14

What is the phonological similarity effect?

Answer 14

Confusion when letters or words sound similar (ps were more likely to write down the wrong SOUNDING letter, rather than a letter that looked like it - “F” was confused with “S” rather than “E”)

Significance: Shows that we remember things by repeating them to ourselves.

Question 15

What is the word length effect?

Answer 15

We remember shorter words better than longer words (as longer words take longer to rehearse and take longer to produce during recall)

Question 16

What is articulatory suppression and how does it support the phonological loop theory?

Answer 16

When we interrupt the rehearsal process with an irrelevant sound, memory of short AND long words suffer!

Question 17

How did Shepard and Metzler’s experiment on rotated shapes provide evidence for the existence of the visuospatial sketchpad?

Answer 17

Method:
- S&M measured reaction time of ps as they decided whether pairs of objects in different orientations were the same or different.

Findings:
- Reaction times were slower for greater differences in orientation.

Significance:
- S&M inferred that ps were solving the problem by rotating an image of the object in their mind (mental rotation) –> This act must involve the visuospatial sketchpad, as it involves visual rotation through space!

Question 18

What have brain damage studies shown about the role of the central executive?

(What does the tendency of frontal lobe patients to engage in perseveration behaviors show about the central executive’s role in controlling attention?)

Answer 18

Frontal lobe plays a prominent role in working memory

• Patients with damage to their frontal lobe therefore have problems with controlling their attention –> exemplify perseveration (repeatedly performing the same action/thought even if it does not achieve their goal)

Question 19

What do ERP (event related potential) studies show about the role of the central executive in controlling attention?

Answer 19

ERP is recorded using small disc electrodes placed on a person’s scalp –> greater ERP = more working memory capacity is being used

• When ps with high working memory capacity vs ps with low working memory capacity were shown distracting stimuli, ERP of low capacity group increased much more –> means that central executive functions less well for ps with low working memory capacity, as they have a harder time focusing!

Question 20

What is the episodic buffer?

Answer 20

A component of working memory that is still in early stages of development, but main functions are:

• Stores information (provides extra capacity)
• Connected to LTM (helps make interchanges between working memory and LTM)
• Explains what the original model can’t –> Why some people can hold more than would be expected based on just the phonological loop and visuospatial sketchpad.

Question 21

How does the “delayed-response task” experiment support the role of the prefrontal cortex in working memory?

Answer 21

Method:

• Show monkey two wells of food, one which has food reward in it.
• Delay (screen is lowered)
• Monkey must remember which well contained food

Findings:
- Monkeys can be trained to perform this task well. HOWEVER, when prefrontal cortex was removed in monkeys, their performance dropped to chance levels, and they picked the correct well only 50% of the time!
————–
Significance:
- PF cortex is important for holding info for short periods of time.

Question 22

What did recording from neurons in a monkey’s prefrontal cortex while it carried out a delayed response task show about the role of the PF cortex in working memory?

Answer 22

Findings:
- Neurons respond when and stimulus is shown and CONTINUES to respond DURING DELAY

*This allows for the memory of the object to remain available for as long as the neurons continue to fire!

Question 23

What do fMRI studies (“neural mind-reading) show about the role of the visual cortex and other brain areas in working memory?

Answer 23

• Researchers used fMRI to predict what images ps were looking at or what they were holding in their memory during a delay –> were able to predict what ps were thinking of with high accuracy rates!
• Shows that PF cortex and other brain areas are involved in working memory –> evidence for distributed representation.

Question 24

What were the main findings of study that investigated how working memory can affect math performance?

Answer 24

• Increasing load on working memory, whether through 1) introducing a second task (e.g. Holding a string of letters in memory) or 2) causing ps to worry about their performance = lowered math performance!
• Writing about worries before completing the math task helped decrease errors!