Chapter 7 Psychology: Memory

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

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

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.

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?

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

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

Understanding how users think Example 1 Which of these are easiest to remember? “7935” or “4359810350703981” “0020-2-735-8888” or “469268731056” “djsgmpukhszqplmyobkjktj” or “the quick brown fox jumps over the lazy dog” Why?

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.

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

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

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

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

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

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

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

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

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

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

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.

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.