1. Chapter 7
Psychology: Memory

2. By the end of this lecture you should know...
About developments in psychology
About cognitive psychology in particular
The mind as information processor
About the model human processor
About how MHP can be used in the design of interactive systems

3. 7.1 Introduction
If you want to develop effective, interactive systems, then you need a fundamental understanding of your users’ psychology
Cognitive psychology:
is an advanced branch of psychology,
is relevant to ICT and
allows us to understand how people perceive, retain and use information to perform mental or cognitive tasks
Model Human Processor (MHP)
Is a theory of cognitive psychology that
seeks to specify the information processing demands on and of users
Aim of MHP
Designs system that are compatible with their users
Evaluate existing systems and their variants
Make quantitative predictions about their use

4. 7.2 Psychology: Memory
Idea of psychological theory is that it explains and predicts human behaviour
We use a model to present such a theory
Given a model of
(i) how a computer system behaves,
(ii) the required tasks and
(iii) the users’ behaviour
we can predict the behaviour of the whole interactive system
A model allows us to design an interactive system to be more usable without having to test it directly on a large number of users.

5. 7.3 Background psychology
Freud
Psychology is popularly associated with Sigmund Freud and his psychoanalysis
Modern psychologists still refer to his work although his methods was not quite scientific
He established the complexity of the human mind
Humans need to be considered in terms of emotions, motivations, cognition & rational thinking
Behaviourism
Pavlov and his dog
Shows a link between input (stimuli) and output (response)
Association or reward could condition human & animal behaviour.
Measuring behaviour is more objective than asking someone to describe what they are doing
Neuropsychology
The brain is made up of a network of 10 billion neurons
Over 100 billion billion possible interconnections
Human behaviour is emergent from the complexity of the interconnections – from the application of a set of simple rules
Challenge: How do we discover at least some of these rules?

6. 7.4 Cognitive psychology
Cognitive Psychology builds on strengths of four approaches:
Following Freud, it accepts the complexity of human cognition and the need to consider a combination of cognition, emotions and motivation & rational thinking
Like behaviourism, looks at stimuli and responses
Also describes internal mechanisms that give rise to behaviour
Artificial Intelligence (AI)
Based on early computer simulation work
If you can program a computer to behave intelligently, then you must have some idea of what intelligence is
Phenomenology
Emphasises people’s subjective experiences and seeks to relate existing behaviour and experience

7. Cognitive Psychology
Cognitive Psychology = Overall approach to understanding human performance and related issues. Applied cognitive science = directed to the solution of real-world problems, e.g. design of interactive systems / websites

8. Understanding how users think
Example 1
Which of these are easiest to remember?
“7935” or “ ”
“ ” or “ ”
“djsgmpukhszqplmyobkjktj” or “the quick brown fox jumps over the lazy dog”
Why?

9. Example 2
GREEN
BLUE
BLACK
YELLOW
ORANGE
GREY
PIENK
RED
Read the words aloud. How difficult is it not to say the colour rather than the word?
Experiments have shown that even simple changes in what is expected can cause significant difficulties in interpretation.

10. These examples….
May not be directly relevant to computer system design, but
Indicate something about how our minds work
Highlight some of the things people find difficult and things people find easy
Such knowledge can inform the way we design usable user interfaces

11. Can you memorise the letters?
Chunking Example
Can you memorise the letters?
A Z M B X N C Y L

12. Chunking Example
And these?
A Z M B X N C Y L

13. Chunking Example
And these?
A B C L M N X Y Z

14. 7.5 The model human processor (MHP)
Perception
Long term memory
Short term memory
Cognitive
processing
Response

15. MHP (continued) MHP was the first simplistic theory of human cognition
It models people as information processors with particular characteristics and abilities
Was never intended to be a full & detailed theory of Psychology (although sometimes criticized as if it were)
Was intended as a simplistic theory to guide and illuminate good practice in ICT

16. Working memory limits
MHP: properties of STM to model and predict human performance
Decay time: 10-20s
Maintained and increased with rehearsal
Size: It can hold 7  2 items
What is an item?
A ‘chunk’ of information, e.g. a word, letter, meaningful sentence, logically grouped items
bjsncvfqwlr
the quick brown fox jumped over the lazy dog
Size of chunks – small influence on memory

17. Long term memory (LTM) LTM different properties to STM
Organised as a network of connected “chunks” of knowledge
Facts
Definitions
Meanings
Procedures
Recall from LTM with aid of:
recollection
association
And by matching with available information

18. Recognition and recall
Different forms of remembering:
recognition
stimulus allows retrieval from LTM
recall
no stimulus; may involve a “search”
Guidelines such as
“Use recognition instead of recall”
Example:
Use of icons (recognition)
vs.
key combinations (recall)
Control-X, Control-C, Control-V

19. Practical Memory guidelines based on STM & LTM strengths and weaknesses
Support recognition rather than recall
Reduce working memory load
Support chunking by structuring information to facilitate memory
Frequent activities become automatic and so don’t require conscious attention

20. Simplex One
MHP has led to a number of more advanced simplistic theories such as Simplex. Simplex One is typical of current views of the architecture of human cognition.
Refer to ch 2, p30.

21. Consequences of Simplex One approach for Interactive Systems Design
An interactive system must provide suitably designed input to the user (input store)
A well-designed system must support the user’s responses and allow them to be made easily (motor output store)
A system should not require an excessive amount of information to be stored in working memory
A system should provide the user with appropriate information for long-term associative store or long-term memory use, in the correct form and so that learning may be optimised
The system should support the executive or processing system by ensuring that the tasks are required by the system are not too complex to be mastered and maintained.