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CMP2019M Human-Computer Interaction
Week 2 – Core Concepts: Cognition

This week
A brief look through some core concepts in HCI:
• Part I: Understanding Human Cognition (Psych 101) – Perception,
– Memory – Learning
• Part II: Designing for Human Cognition – Usability
– Design Heuristics
• Sheiderman & Nielsen

Part I: Understanding Human Cognition

…what is cognition?

Deals with our perception: how we see the world, how we store information about it, and how we recall it.
(= our ability of making sense of the world around us.)

Cognitive Science = science concerned with (human) information processing.

Why should we be concerned with cognition if we’re developing software?

Because our body is our interface to communicate with technology.

Relevant to HCI:
(1) Perception & Attention (2) Memory
(3) Learning

Cognition (1) Perception & Attention

Long-term Memory
Sensory Input
Short-Term Memory
Attention
Rehearsal
..

Perception
• Receive information through senses – sight
– hearing – touch
• Processinformationtoacquire – knowledge
– understanding
• ..and then do stuff
..

Perception
• Interestingly, the study of visual perception offers evidence that the world or the image is not ‘given’, but constructed.
• What we CAN perceive is very different to what we DO perceive

Perception
http://thebrain.mcgill.ca

Perception
We can’t process everything we see and hear and the information we extract, for example, from computer interfaces depends on:
 our motivation
 our arousal
 individual differences  cultural differences
Attention!!

Long-term Memory
Sensory Input
Short-Term Memory
Attention
Rehearsal
..

Attention
• Attention is the cognitive process of selectively concentrating on one aspect of the environment while ignoring other things.
• Attention has also been referred to as the allocation of processing resources.
• The way we perceive the world around us is entirely dependent on how the brain interprets and constructs meaning
• We are BOMBARDED by input
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Attention
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Attention
• We attend to different inputs selectively – otherwise we would not be able to cope
• perception is active and constructive not just receptive
• Implications:
– Perception is not perfect – It can be fooled
– When designing, must help users construct the correct interpretation
..

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What did you read?
• A Bird In The Bush
• A Bird In The The Bush
..

Active Perception
• We search for meaning
• Scaninputveryquickly
• Look for meaningful patterns
• Ignore
– what doesn’t make sense
– what can’t easily be decoded
..

..

Perception
• Wereceiveinput
• Weneedtoassimilateit
• To construct our understanding
• Based on experience
• Brain interprets and makes sense of input in the light of previous knowledge and experience (basic experiments in psychology)
..

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Interpreting Input
• Brain makes assumptions/interpretations
• Fills in missing details
• Ambiguitycausesusto’see’differentthings
• i.e.–thewayweperceivetheworldaroundusis entirely dependent on how the brain interprets and constructs meaning
..

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Interpreting Input
• We’re great at pattern recognition
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Implications for Design
• Our brain is desperate to make sense of the information that it receives – but can sometimes be overwhelmed
• Do not bombard the user with every function at the same time
• Drawusersattentiontoappropriatefunctionsat appropriate times
• Fine grain details should be accessible only when needed
..

Cognition (2) Memory

Memory
• Canmean:
– How we store new information – Remembering
• Theoristssuggest
– short-term memory – working memory
– long-term memory
• Computeranalogy
– registers, RAM, backing storage
..

Long-term Memory
Sensory Input
Short-Term Memory
Attention
Rehearsal
..

Short-term Memory
• Weforgetmostthings
• Limitedcapacity
– 7 plus/minus 2 (Miller, 1956)
• Recallversusrecognition – Recognition is easy
– Recall is difficult
..

Short-term Memory
Remember the following:
1586765
..

Short-term Memory
What do you remember?
XXXXXXX
..

Short-term Memory
Remember the following:
9116661337
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Short-term Memory
What do you remember?
XXXXXXXXXX
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Short-term Memory: Chunking
Remember the following:
911
666 1337
..

Gestalt Psychology
• Our brains want to find patterns and lump information together to make sense of the world
1) Principle of proximity 2) Principle of closure
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Translating into Design
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Working Memory
• An area where current processing takes place
• In conjunction with inputs from short-term memory and long-term memory
• New information, plus old knowledge • Problem-solving
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Short-term & Working Memory
• Information is easily lost before transfer to long-term memory
– Disruption/interruption – Visual distraction
• Anxiety, frustration, distraction impede information processing
• Familiarity aids information processing and chunking
..

Long-term Memory
Sensory Input
Short-Term Memory
Attention
Rehearsal
..

Long-term Memory
• verylarge-~infinite
• associative-timeneededtoretrieve
• Involvement in working memory processes
..

Kinds of Knowledge / Memory
• What kinds of things do you forget?
• What do you not forget?
..

Long-term Memory
http://thebrain.mcgill.ca
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Recognition and Recall
• People are better at recognizing things they have previously experienced than recalling those things from memory.
• ……becauserecognitiontasksprovide memory cues that facilitate searching through memory.
• Example: command line versus GUI
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Implications
• When using a computer, people are already using quite a lot of short term and working memory.
• Remember, they are normally doing a task, using the computer as a tool.
• You shouldn’t have to think about the tool.
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Implications
• Reducememoryload
– Don’t make people remember information, it should be on-screen if needed
– Recognition over Recall
– Show menus – and show path – maintain consistency……..
• of screen components – where’s the menu • of menu structures
• of commands
• Make navigation clear and obvious
..

Recognition and Recall
• Remember: People are better at recognizing things they have previously experienced than recalling those things from memory.
• Can you think of any advantages that recall might have?
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Expert Interfaces
• In some cases, recall is more efficient than recognition.
• Whether it makes sense for people to learn how to use an interface depends on the context of use.
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Recognition and Recall
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Recognition
..

Recall
• Customeronlyshopsfor bananas every few days.
• Clerk at checkout deals with bananas a bunch of times a day. Every day.
• Consoleinterfacesare usually flat (no hierarchy) and therefore faster.
• Whatabouterrors?
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Cognition (3) Learning

Long-term Memory
Sensory Input
Short-Term Memory
Attention
Rehearsal
..

Intro to Learning
• What is learning?
– Acquiring new knowledge, behaviours, skills, values, preferences or understanding.
– Generally after learning you can do something that you couldn’t do before
• Howdopeoplelearn? – From experience
– From consequences
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Learning from Consequences
• Successful actions will generally be repeated
• Unsuccessfulactionswont
• Depends on the feedback that you receive
– For example, a nice haircut, a hot saucepan handle.
• It is crucial that feedback is timely and specific. The system should be responsive.
• Problemsoccurwhenfeedbackisnot specific enough to allow us to infer cause- effect relationships.
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Learning from Consequences
• Successful actions will generally be repeated
• Unsuccessfulactionswont
• Depends on the feedback that you receive
– For example, a nice haircut, a hot saucepan handle
• YOUHAVETHREESECONDS
• IF YOU ARE TOO SLOW, YOUR CAT WILL TRY THIS ANOTHER 100 TIMES
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Learning
• Learning from direct consequences is important, but quite easy
• Other things are not so easy to learn, depending on a number of factors
– For example, unstructured material is very hard to learn
– we need to order, categorise, make sense of things
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Learning
• We learn something when it is useful
• Learning is fastest when we can
– Identify cause and effect
– Use prior knowledge to interpret
– Make connections, make things meaningful – Make things obvious, intuitive – affordances
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Affordances
• The perceived properties of the object that suggest how one could use it (Gibson, 1977)
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Affordances
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Affordances
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Learning Computer Systems
• The user should have as little learning as possible to do – they are interested in the task, not the system
– time spent learning the system is perceived as a waste of time
• Make use of existing knowledge & Affordances
• System should be transparent rather than obstructive
• It should be obvious to see cause and effect between actions of user and consequences on the system or task. (i.e. not MS Word)
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Learning Computer Systems
• Help users learn your system, but get the timing right.
• Don’t keep users from what they’re actually trying to accomplish.
• Makehelpoptional.
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Learning Computer Systems
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Remember:
We should care about cognition etc. because our body is our interface to communicate with technology.

Next week: Beyond Cognition – Designing Usable Systems

Do you have any questions?