§7-Cognitive aspects

Question 1

Why Cognitive Psychology for Interaction Design?

Answer 1

1. understand the world view of the user
2. to design the interface in a way which is consistent with the world view
   EXAMPLES?

Question 2

List five tools for understanding how humans think

Answer 2

1. The Model Human Processor
2. Core aspects of cognition
3. Memory
4. Gestalt psychology
5. Human perception

Question 3

(tool 1) three components of the model human processor

Answer 3

1. perceptual
2. cognitive
3. motor

Question 4

Describe the perceptual subsystem

Answer 4

• input: senses (visual, auditory, haptic)
• fed into visual image store, audio image store, via perceptual processor
  1. information is stored in memory (sensory, working/ST, LTM)

Question 5

Describe the cognitive subsystem

Answer 5

1. output of perceptual subsystem is fed into working memory (STM)
2. exchanges between LTM, STM and the cognitive processor
3. output from working memory to the motor subsystem

Activities of the cognitive processor

1. reasoning,
2. skill acquisition
3. error feedback

Question 6

Describe the movement subsystem

Answer 6

1. output from cognitive subsystem into motor processor

2. motor processor drives the movement response

Question 7

Processor cycle times and consequences

Answer 7

1. Tperceptual > Tcog, Tmot
2. Tperceptual is shorter for more intense stimuli
3. Tmotor ~ Tcog
4. allows a system designer to predict the time it takes to complete a task

Question 8

(tool 2) list four core cognitive aspects

Answer 8

1. perception and recognition
2. memory
3. reading, speaking listening,
4. problem solving,…, learning

Question 9

what are the three types of memory, how is info transferred between them

Answer 9

Three types of memory

1. sensory buffers
2. short term memory
3. long term memory
   - attention moves info from sensory buffers to STM
   - rehearsal moves from STM to LTM
   - recall moves info from LTM to STM

Question 10

Properties of sensory/perceptual memory

Answer 10

1. buffers for stimuli, passive (only moved to STM if user pays attention)
2. constantly overwritten by new information (kept for ~0.5 s before overwritten)
3. either overwritten and lost or passed into a more permanent memory store

Question 11

What is the role of attention

Answer 11

• passes information from sensory memory to STM

- defined as concentration on one out of a number of competing stimuli

Question 12

Design implications arising from the properties of sensory memory

Answer 12

1. cannot assume that if a person heard or saw a message 5 secs earlier, they will still remember it (may have been overwritten / not received attention)
2. keep message displayed until not needed; or make it so that the user can apply the information immediately.
3. as focus is directed towards the information, it moves to STM, where it persists for < 10 seconds

Question 13

Consequences of human short term memory limitations

Answer 13

1. rapidly accessible
2. transient
3. limited capacity of 7±2 chunks
4. information subject to interference
5. items are lost from memory if not rehearsed

Question 14

Principle of chunking + examples

Answer 14

1. STM can store 7±2 chunks, mainly regardless of how complex those chunks are

~ STM constrained by number of chunks not basic elements (e.g. digits)

Patterns can be useful as aids to memory by imposing chunks

Examples

1. long list -> categories : thrashing
2. divide up a phone number/registration plate
3. divide up menus

Question 15

Issues about storage of information

Answer 15

1. rehearsal to move info from STM to LTM
2. total time hypothesis – retention is proportional to rehearsal time
3. distribution of practice effect – optimise retention by spreading learning over time (fragmented and repeated rather than massed)
4. structure, meaning and familiarity makes information easier to remember (interface metaphors)

Question 16

Issues about forgetting from LTM

Answer 16

1. decay – information is lost but slowly
2. interference arises when new information replaces old, old may interfere with new
3. selective memory – choose to forget/influence of emotion

Question 17

Issues about retrieval

Answer 17

1. recall – remembering something .e.g password
2. recognition occurs when you are presented with the item you are trying to remember e.g. when listing all files in home directory

Question 18

Example of memory issues in improving a menu interface

Answer 18

text style selector menu

1. modify text to be in the style that it is selecting (recall to recognition)
2. group items by text alignment, font modification, … (chunking / avoids thrashing)

Question 19

LTM : context

Answer 19

 Context plays a major role in what people see and hear

Question 20

LTM : mind set

Answer 20

Factors that we know and bring to a situation can have a profound effect on the usability of an interface

e.g. meaning of certain colours, assumptions about the behaviour of interface metaphors

Question 21

LTM : grouping

Answer 21

If you do not try to add grouping into the interface… the user’s perceptual processes will still try to impose a structure
on the display
- and it might not be the structure you want!

EXAMPLES?

Question 22

Define Gestalt psychology

Answer 22

• idea: we do not see things in isolation but as parts of a whole
• structured layouts are easier to perceive
• importance of context in aiding perception

Question 23

List the six gestalt laws

Answer 23

1. figure ground relationship
2. proximity
3. similarity
4. symmetry
5. continuity
6. closure

Question 24

Gestalt: figure ground relationship

Answer 24

we group elements either as figures or ground

affects legibility – contrast of black text upon a dark background

Question 25

Gestalt: proximity

Answer 25

we group by distance consistency of fonts -- suggests that similar actions are performed by each thing

Question 26

Gestalt: similarity

Answer 26

we group by type (font/colour/...)

Question 27

Gestalt: symmetry

Answer 27

we group by meaning (or distinguish by meaning) menus on opposite sides of screen

Question 28

Gestalt: continuity

Answer 28

we group by alignment or flow (even if the lines were drawn in a way which might suggest an alternative grouping)

Question 29

Gestalt: closure

Answer 29

we perceive things which are not (completely) there e.g. present an icon -- of a person, as a semicircle and a circle removes irrelevant information -- provides an abstraction -- doesn't distract from what the purpose of the button is

Question 30

(tool 5) visual perception -- what are its key properties

Answer 30

visual perception is active (more likely to be transferred into STM)

Question 31

What is selective attention and perceptual expectancy

Answer 31

selective attention -- ability to ignore the irrelevant perceptual expectancy -- seeing what we expect to see

Question 32

Issues related to visual perception involved in reading

Answer 32

Stages 1. perception of the visual pattern of a word -- cues are important, removed by e.g. capitalisation (but that may force users to slow down, so may therefore be useful for highly important messages). 2. decoding wrt internal representation

Question 33

Issues related to visual perception involved regarding expectation

Answer 33

What we expect to see affects what we perceive reality to be 1. e.g. paris in the the spring

Question 34

Issues related to visual perception related to colour

Answer 34

perception of an object is determined by the physical context of the object

Question 35

list of types of colour schemes

Answer 35

1. Monochromatic : based on different tones of same colour 2. Analogous: based on colours that are adjacent to each other on the colour wheel 3. Complementary: based on colours that are on opposite sides of the colour wheel 4. Triadic: based on three colours equally spaced around the colour wheel

Question 36

Four key consequences of cognitive aspects for interaction design

Answer 36

1. Users see what they expect to see .: be consistent, exploit prior knowledge 2. Users have difficulty focussing on more than one activity at a time: group similar things together, give prominence to important items; reduce thrashing 3. Structured layouts are easier to perceive: use the Gestalt laws 4. It is easier to recognise than to recall -- put the knowledge that the user needs in the user interface rather than forcing them to rely on remembered knowledge -- less burden on STM and faster (avoid need for recall from LTM)