Human Memory

Question 1

Multi-Store Model

Answer 1

Sensory and long-term memory (LTM) are actual stores

Working memory (WM) is not an actual store
- Subset of sensory and long-term stored information that becomes activated for conscious processing
- Also called “short-term memory” (STM) but Wm captures better that this a subset of memory activated “to work on”
- Perfectly fine to use “STM” when the emphasis is on the short-term nature of available information

Question 2

Working Memory and Attention

Answer 2

• Working memory retains information for a brief period while performing mental operations on that information
• Attention is the process of focusing our awareness on a particular goal or information
  a. A goal we have in mind, or stored information we think about
  b. Information in the world, something we see or hear and focus on

Question 3

What is working memory directly related to?

Answer 3

Attention

• Contains information selected by the current focus of attention
• Information brought to the foreground of our awareness
• Literally, bits of information “fired up” in the brain
• Can be triggered by perception, or by thought

Question 4

Structure of Working Memory

Answer 4

• Central executive coordinates attention, makes decision, triggers action
• Phonological loop processes speech, language and sound
  a. Inner voice that repeats speech input to keep longer in store
  b. Also transforms visual language into phonological representation
• Visuo-spatial sketchpad processes visual and spatial information
  
  • Similarly, a visual representation for the “inner eye”
• Episodic buffer processes episodic information / experiences

Question 5

Working Memory has limited capacity

Answer 5

• Working memory can only store a very small number of items
  
  • Only 3 or 4 items if they are random - More, if they have some connection (words in a sentence / items that share features or are in some pattern)
  • “the magical number of seven plus minus two”, Short-term memory of 5 and 9 digits/word

Question 6

Chunking

Answer 6

• The limit is the number of items (“chunks”), not the amount of information
  
  • A long word can be remembered more easily than a sequence of letters (if it is a familiar word)
• Chunking: combining information into chunks
  
  • Smaller pieces of information can be combined and memorized in larger chunks (fewer items)
  • For example phone numbers, as 4 chunks of double-digits
  • FMLWTFBRB memorized as chunks FML WTF BRB
• Representation matters
  
  • Same information can be encoded differently
  • Some representations easier to remember than others, e.g. names/word instead of numeric codes

Question 7

Working memory is volatile

Answer 7

• Information is only available for a brief period
  
  • “Refresh” in the phonological loop and/or visual sketchpad requires unbroken attention
  • Around 10 sec, up to 20-30s
• Information is easily lost from working memory
  
  • Displaced when we shift attention from one (sub-) task to the next
  • Depends on how many ‘memory slots’ the new task needs
  • Distractions that break out concentration
    
    • Forgetting what we wanted to do
    • Mild wandering

Question 8

Structure of Long-Term Memory

Answer 8

Question 9

Encoding

Answer 9

Forming a mental representation of an experience
- Memory is formed from experience
- Can be encoded in different ways

Question 10

Storing

Answer 10

Forming associations
- Reinforced by reactivation (learning, rehearsing)
- Features associated with an experience might not be reinforced in the same way (e.g. learning how to use a system operation, but not remembering through which menu it can be accessed)

Question 11

Retrieval

Answer 11

‘fetching’ stored memory for processing in working memory
- Recognition: retrieval triggered by perception (seeing or hearing something similar to what is stored)
- Recall: retrieval by “memory search” based on mental cues

Question 12

Storage: Semantic network

Question 13

Retrieval: Activation of Memory

Answer 13

Activation: how easily a chunk of information can be retrieved from memory

Influenced by three factors:
1. Practice: how many times a chunk has been used in the past (More easily retrievable when used frequently)
2. Recency: how recently a chunk has been used (More easily retrievable when used recently)
3. Context: what is present in the person’s focus of attention (More easily retrievable when associated with information in working memory)

Question 14

Recognition

Answer 14

• Recognition is easy
  
  • Retrieval aided by external information
  • Perception provided cues for matching against stored information
    
    • For example, recognising faces in a fraction of a second
    • Reactivation of a stored pattern of features
  • Depends on context

Question 15

Recall

Answer 15

• Recall is hard
  
  • Memory search without external help
  • Fewer cues: only what we can think of “search terms”
  • Easier when stored information is associated with variety of cues through which it can be reached

Question 16

Example: macOS Spotlight

Answer 16

• Combination of search and browsing
• Supports recall based on search terms
• Supports recognition by showing results with multiple cues
  
  • Categories
  • Icons
  • Names
• Recognition also supported by preview of content

Question 17

Spatial Memory

Answer 17

• Location recall is important in UI design
  
  • Reinforced by consistent, repeated use
  • Saves time on visual search
  • Leads to automaticity
• Boundaries and Landmarks are important (e.g. toolbars, search boxes)
  
  • Scaling = good; Reflowing = bad?

Question 18

Spatial Memory is Fuzzy

Answer 18

• An inexact representation
  
  • We approximate locations
  • Variable ability between users
  • Can improve over time
• Using spatial memory in design
  
  • Avoid adaptive interfaces (duplicate content, don’t rearrange)
  • Use imagery to support recognition (icon/text)
  • Bigger monitor = see more items = improvement

Question 19

Memory - Key Points

Answer 19

• Working memory retains information for a brief period while performing mental operations on that information.
• WM is closely linked to attention, has very limited capacity and is highly volatile.
• When information needs to be kept in the short-term, make the computer remember it, not the user.
• Long-term memory is formed from experience and stores chunks of information that are connected by associations
• Retrieval from memory depends on how information is encoded and the cues available for access.
• Recognition is easy. Recall is hard.