Lecture Note Topic 2.pptx

SKM 3463: Human-Computer Interaction Week 2: The human Human Outline 1) Input-output channels: vision, hearing, touch and movement 2) Memory: sensory, short-term memory and long term memory 3) Thinking: deductive, inductive and abductive reasoning; problem solving 4) Emotion 5) Indiv...

SKM 3463: Human-Computer Interaction Week 2: The human Human Outline 1) Input-output channels: vision, hearing, touch and movement 2) Memory: sensory, short-term memory and long term memory 3) Thinking: deductive, inductive and abductive reasoning; problem solving 4) Emotion 5) Individual differences and psychology  1) Input-output channels In an interaction with a computer – the user receives information - output by the computer – The user responds - input to the computer In HCI, the input in the human occurs mainly through sight, hearing and touch. In HCI, the fingers play the primary role as an effective effecter with some use of voice, eye, head and body position. 1) Input-output channels Humans are limited in their capacity to process information. This has important implications for design. Information is received and responses given via a number of input and output channels: – visual channel – auditory channel – haptic channel – movement 1) Input-output channels: visual channel Interpreting the signal – Size and depth visual angle indicates how much of view object occupies (relates to size and distance from eye) visual acuity is ability to perceive detail (limited) familiar objects perceived as constant size (in spite of changes in visual angle when far away) cues like overlapping help perception of size and depth 1) Input-output channels: visual channel Interpreting the signal – Brightness subjective reaction to levels of light affected by luminance of object measured by just noticeable difference visual acuity increases with luminance as does flicker – Colour made up of hue, intensity, saturation cones sensitive to colour wavelengths blue acuity is lowest 8% males and 1% females colour blind 1) Input-output channels: visual channel Interpreting the signal – The visual system compensates for: movement changes in luminance (the amount of light reflected by the object’s surface). – Context is used to resolve ambiguity – Optical illusions sometimes occur due to over compensation Visually perceived images that differ from objective reality. 1) Input-output channels: visual channel Optical Illusions the Ponzo illusion the Muller Lyer illusion 1) Input-output channels: visual channel Optical illusions and design focus – Optical illusions highlight the differences between the way things are and the way we perceive them – In interface design, we will not always perceive things exactly as they are – The way the objects (geometric shapes) are composed together will affect the way we perceive them 1) Input-output channels: visual channel Reading – Several stages: visual pattern perceived decoded using internal representation of language interpreted using knowledge of syntax, semantics, pragmatics – Word shape is important to recognition – Negative contrast improves reading from computer screen 1) Input-output channels: visual channel which way is lock and It's too easy to misread this which way is unlock? message Better: Symbols of a locked Better: Use a critical message box and unlocked (open) [with the big, red X icon] and the padlock at either end of phrase "not successful." the switch. 1) Input-output channels: auditory channel Provides information about environment: distances, directions, objects etc. Physical apparatus: – outer ear – protects inner and amplifies sound – middle ear – transmits sound waves as vibrations to inner ear – inner ear – chemical transmitters are released and cause impulses in auditory nerve Sound – pitch – sound frequency – loudness – amplitude – timbre – type or quality 1) Input-output channels: haptic channel Provides important feedback about environment. May be key sense for someone who is visually impaired. Stimulus received via receptors in the skin (touch): – thermoreceptors – heat and cold – nociceptors – pain – mechanoreceptors – pressure (some instant, some continuous) Some areas more sensitive than others e.g. fingers. Kinethesis - awareness of body position – affects comfort and performance. 1) Input-output channels: movement Time taken to respond to stimulus: reaction time + movement time Movement time dependent on age, fitness etc. Increasing reaction time decreases accuracy in the unskilled operator but not in the skilled operator. 2) Memory memory is an organism's ability to store, retain, and recall information and experiences. Information is stored in memory: – sensory memory – short-term (working) memory – long-term memory 2) Memory There are three types of memory function: Sensory memories Short-term memory or working memory Long-term memory Information from short-term memory is stored in long- term memory by rehearsal 2) Memory: sensory memory Sensory memory corresponds approximately to the initial 200–500ms after an item is perceived. E.g. The ability to look at an item, and remember what it looked like with just a second of observation, or memorization. 2) Memory: sensory memory Buffers for stimuli received through senses, very temporary and fade quickly. – iconic memory: visual stimuli – echoic memory: aural stimuli – haptic memory: tactile stimuli 2) Memory: sensory memory Iconic memory – memory of visual stimuli – it is how the brain remembers an image you have seen. – occurs in the form of mental pictures – lasts very briefly before quickly fading – slightly shorter periods of time than echoic memories (auditory memories) 2) Memory: sensory memory Echoic memory – a very brief sensory memory of some auditory stimuli – only retained for a short period of time (3-4 seconds) – slightly longer periods of time than iconic memories (visual memories) 2) Memory: sensory memory Haptic memory – Sensory memory for the tactile sense of touch – detect sensations such as pressure, itching, and pain 2) Memory: Short-term memory (STM) Scratch-pad for temporary recall – rapid access ~ 70ms – rapid decay ~ 200ms – limited capacity – Chunking of information (closure) can lead to an increase in the short term memory capacity  2) Memory: Short-term memory (STM) a hyphenated phone number is easier to remember than a single long number 12101986 - 12, 10 and 1986, 012-141 2626 1-300-88-2525 XIBMSATATTPHDX X IBM SAT ATT PHD X 2) Memory: Long-term memory (LTM) Repository for all our knowledge – slow access ~ 1/10 second – slow decay, if any – huge or unlimited capacity – storage of information over a long period Two types – episodic – serial memory of events , experiences (e.g. your last b-day party) – semantic – structured memory of facts, concepts, skills – (e.g. friends’ names, word meanings, etc) semantic LTM derived from episodic LTM 2) Memory: LTM - Storage of information rehearsal – information moves from STM to LTM distribution of practice effect – optimized by spreading learning over time structure, meaning and familiarity – information easier to remember 2) Memory: LTM - Forgetting decay – information is lost gradually but very slowly interference – new information replaces old: retroactive interference – old may interfere with new: proactive inhibition so may not forget at all memory is selective … … affected by emotion – can subconsciously `choose' to forget 2) Memory: LTM - retrieval recall – information reproduced from memory can be assisted by cues, e.g. categories, imagery recognition – information gives knowledge that it has been seen before – less complex than recall - information is cue 3) Thinking deductive, inductive and abductive reasoning problem solving  3) Thinking: Deductive Reasoning Deduction: – derive logically necessary conclusion from given premises. e.g. If it is Friday then she will go to work It is Friday Therefore she will go to work. Logical conclusion not necessarily true: e.g. If it is raining then the ground is dry It is raining Therefore the ground is dry 3) Thinking: Deductive Reasoning When truth and logical validity clash … e.g. is A = B and B = C, then A= C e.g. All birds have feathers and robins are birds, so robins have feathers. e.g. All dolphins are mammals, all mammals have kidneys; therefore all dolphins have kidneys. Correct? 3) Thinking: Inductive Reasoning Induction: – generalize from cases seen to cases unseen e.g. all elephants we have seen have trunks therefore all elephants have trunks. Unreliable: – can only prove false not true … but useful! Humans not good at using negative evidence 3) Thinking: Abductive reasoning reasoning from event to cause e.g. Sam drives fast when drunk. If I see Sam driving fast, assume drunk. e.g. The lawn is wet. But if it rained last night, then it would be unsurprising that the lawn is wet. Unreliable: – a kind of logical inference described as "guessing“ – can lead to false explanations 3) Thinking and the Design of Interactive System Examples: the desktop metaphor is an interface metaphor which is a set of unifying concepts used by GUI to help users more easily interact with the computer. It treats the monitor of a computer as if it is the user's desktop: – the objects ( documents and folders of documents) can be placed – a document can be opened into a window – Small applications (a desk calculator or notepad, trash can, etc.) are also available. 3) Thinking and the Design of Interactive System The interface is a conceptual metaphor Desktop metaphor of a writing desk 3) Thinking and the Design of Interactive System 4) Problem solving Errors and mental models Types of error slips – right intention, but failed to do it right – causes: poor physical skills, inattention etc. – change to aspect of skilled behaviour can cause slip mistakes – wrong intention – cause: incorrect understanding humans create mental models to explain behaviour. if wrong (different from actual system) errors can occur 4) Problem solving and the Design of Interactive System Examples – Help users recognize, diagnose, and recover from errors Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution. – Help and documentation Documentation may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large. 4) Emotion The biological response to physical stimuli is called affect Affect influences how we respond to situations – positive creative problem solving – negative narrow thinking “Negative affect can make it harder to do even easy tasks; positive affect can make it easier to do difficult tasks” (Donald Norman) 4) Emotion Implications for interface design – stress will increase the difficulty of problem solving – relaxed users will be more forgiving of shortcomings in design – aesthetically pleasing and rewarding interfaces will increase positive affect 3) Emotion and the Design of Interactive System Examples: – Flexibility and efficiency of use The interaction for the novice and the expert user such that the system can cater to both inexperienced and experienced users. – Aesthetic and minimalist design Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information. 5) Individual differences long term – sex, physical and intellectual abilities short term – effect of stress or fatigue changing – age Ask yourself: will design decision exclude section of user population? Summary The human is an information processor, receiving inputs from the world, storing, manipulating and using information and reacting to the information received. Information is received through the senses, particularly in the case of computer use, through sight, hearing and touch. Summary Information is stored in memory, either temporarily in sensory or working memory, or permanently in long-term memory. Information can then be used in reasoning and problem solving and recurrent familiar situations allow people to acquire skills in a particular domain. Summary Human perception and cognition are complex and sophisticated but they are not without limitations. An understanding of the capabilities and limitations of the human as information processors can help in design of interactive systems which support the capabilities and compensate for the limitations. The principles, guidelines, techniques and models which can be derived from cognitive psychology are invaluable tools for the designers of interactive systems.