Chap1-The-Human (1).pdf

chapter 1 the human the human Information i/o … – visual, auditory, haptic, movement Information stored in memory – sensory, short-term, long-term  Information processed and applied - reasoning, problem solving, skill, error Emotion influences human capabilities Each person is...

chapter 1 the human the human Information i/o … – visual, auditory, haptic, movement Information stored in memory – sensory, short-term, long-term  Information processed and applied - reasoning, problem solving, skill, error Emotion influences human capabilities Each person is different Vision Two stages in vision physical reception of stimulus processing and interpretation of stimulus The Eye - physical reception mechanism for receiving light and transforming it into electrical energy light reflects from objects images are focused upside-down on retina retina contains rods for low light vision and cones for colour vision ganglion cells (brain!) detect pattern and movement 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 Interpreting the signal (cont) 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 Interpreting the signal (cont) The visual system compensates for: – movement – changes in luminance. Context is used to resolve ambiguity Optical illusions sometimes occur due to over compensation  Optical Illusions the Muller Lyer illusion the Ponzo illusion Reading Several stages: – visual pattern perceived – decoded using internal representation of language – interpreted using knowledge of syntax, semantics, pragmatics Reading involves saccades and fixations Perception occurs during fixations Word shape is important to recognition Negative contrast improves reading from computer screen Hearing 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 Hearing (cont) Humans can hear frequencies from 20Hz to 15kHz – less accurate distinguishing high frequencies than low. Auditory system filters sounds – can attend to sounds over background noise. – for example, the cocktail party phenomenon. Touch Provides important feedback about environment. May be key sense for someone who is visually impaired. Stimulus received via receptors in the skin: – thermoreceptors – heat and cold – nociceptors – pain – mechanoreceptors – pressure (some instant, some continuous) Some areas more sensitive than others e.g. fingers. Kinesthesis - awareness of body position – affects comfort and performance. Movement Time taken to respond to stimulus: reaction time + movement time Movement time dependent on age, fitness etc. Reaction time - dependent on stimulus type: – visual ~ 200ms – auditory ~ 150 ms – pain ~ 700ms Increasing reaction time decreases accuracy in the unskilled operator but not in the skilled operator. Memory There are three types of memory function: Sensory memories Short-term memory or working memory Long-term memory Selection of stimuli governed by level of arousal. sensory memory Buffers for stimuli received through senses – iconic memory: visual stimuli – echoic memory: aural stimuli – haptic memory: tactile stimuli Examples – stereo sound Continuously overwritten Short-term memory (STM) Scratch-pad for temporary recall – rapid access ~ 70ms – rapid decay ~ 200ms – limited capacity - 7± 2 chunks Examples 212348278493202 0121 414 2626 HEC ATR ANU PTH ETR EET Closure Closure gives you a nice ‘done it’ when we complete some part of a task. At this point our minds have a tendency to flush short-term memory in order to get on with the next job. Example: Early ATM Machine Long-term memory (LTM) Repository for all our knowledge – slow access ~ 1/10 second – slow decay, if any – huge or unlimited capacity Two types – episodic – serial memory of events – semantic – structured memory of facts,concepts, skills semantic LTM derived from episodic LTM Long-term memory (cont.) Semantic memory structure – provides access to information – represents relationships between bits of information – supports inference Model: semantic network – inheritance – child nodes inherit properties of parent nodes – relationships between bits of information explicit – supports inference through inheritance LTM - semantic network Models of LTM - Frames Information organized in data structures Slots in structure instantiated with values for instance of data Type–subtype relationships DOG COLLIE Fixed Fixed legs: 4 breed of: DOG type: sheepdog Default diet: carniverous Default sound: bark size: 65 cm Variable Variable size: colour colour Models of LTM - Scripts “John took his dog to the surgery. After seeing the vet, he left.” we may fill in a substantial amount of detail.  Models of LTM - Scripts Model of stereotypical information required to interpret situation Script has elements that can be instantiated with values for context Script for a visit to the vet Entry conditions: dog ill Roles: vet examines vet open diagnoses owner has money treats owner brings dog in Result: dog better pays owner poorer takes dog out vet richer Scenes: arriving at reception Props: examination table waiting in room medicine examination instruments paying Tracks: dog needs medicine dog needs operation  Entry conditions Conditions that must be satisfied for the script to be activated. Result Conditions that will be true after the script is terminated. Props Objects involved in the events described in the script. Roles Actions performed by particular participants. Scenes The sequences of events that occur. Tracks A variation on the general pattern representing an alternative scenario. Models of LTM - Production rules Representation of procedural knowledge, our knowledge of how to do something. Condition/action rules if condition is matched then use rule to determine action. IF dog is wagging tail THEN pat dog IF dog is growling THEN run away LTM - Storage of information rehearsal – information moves from STM to LTM total time hypothesis – amount retained proportional to rehearsal time distribution of practice effect – optimized by spreading learning over time – training period was divided into weekly sessions of one hour performed better than those who spent two or four hours a week learning structure, meaning and familiarity – information easier to remember First try to remember the words in list A and testyourself. List A: Faith Age Cold Tenet Quiet Logic Idea Value Past Large Now try list B. List B: Boat Tree Cat Child Rug Plate Church Gun Flame Head *Sentences are easier still to memorize. LTM - Forgetting Two main theories of forgetting decay – information is lost gradually but very slowly interference – new information replaces old: retroactive interference – ex: changing phone numbers – old may interfere with new: proactive inhibition – ex: driving in to your old house. so may not forget at all memory is selective … … affected by emotion – can subconsciously `choose' to forget We tend to remember positive information rather than negative (hence nostalgia for the ‘good old days’), LTM - retrieval 2 Types of information 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  Thinking Reasoning deduction, induction, abduction Problem solving Reasoning is the process by which we use the knowledge we have to draw conclusions or infer something new about the domain of interest. 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 Deduction (cont.) When truth and logical validity clash … Deduction Misapplied e.g. Some people are babies Some babies cry Inference - Some people cry Is this Correct? we are not told that all babies are people People bring world knowledge into the reasoning process 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 e.g. Wason's cards.  Wason's cards 7 E 4 K If a card has a vowel on one side it has an even number on the other Is this true? How many cards do you need to turn over to find out? …. and which cards? Abductive reasoning Abduction: -reasons from a fact to the action or state that caused it. e.g. Sam drives fast when drunk. If I see Sam driving fast, assume drunk. Unreliable: – can lead to false explanations Problem solving -Process of finding solution to unfamiliar task using knowledge. Several theories. Gestalt – problem solving both productive and reproductive – Problem solving is a matter of reproducing known responses or trial and error. – Reproductive problem solving draws on previous experience as the behaviorists claimed, but productive problem solving involves insight and restructuring of the problem. Problem solving (cont.) Problem space theory – problem space comprises problem states – problem has an initial state and a goal state and people use the operators to move from the former to the latter. For example, imagine you are reorganizing your office and you want to move your desk from the north wall of the room to the window. Problem solving (cont.) Analogy – analogical mapping: novel problems in new domain? use knowledge of similar problem from similar domain – process has been investigated using analogous stories Skill acquisition – skilled activity characterized by chunking lot of information is chunked to optimize STM – conceptual rather than superficial grouping of problems – information is structured more effectively – Example: Chess masters – remembers good moves and board configurations Analogy Problem A doctor is treating a malignant tumor. In order to destroy it he needs to blast it with high-intensity rays. However, these will also destroy the healthy tissue surrounding the tumor. If he lessens the rays’ intensity the tumor will remain. How does he destroy the tumor? Analogy A general is attacking a fortress. He can’t send all his men in together as the roads are mined to explode if large numbers of men cross them. He therefore splits his men into small groups and sends them in on separate roads. Errors and mental models Types of error slips – right intention, but failed to do it right – causes: poor physical skill,inattention etc. – change to aspect of skilled behaviour can cause slip – Example: Mistype or accidentally pressing the mouse mistakes – wrong intention – cause: incorrect understanding – Example: you may think that the magnifying glass icon is the ‘find’ function, but in fact it is to magnifythe text. 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) Emotion (cont.) 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 Individual differences long term – gender, physical and intellectual abilities short term – effect of stress or fatigue changing – age Ask yourself: will design decision exclude section of user population? Psychology and the Design of Interactive System Some direct applications – e.g. blue acuity is poor  blue should not be used for important detail However, correct application generally requires understanding of context in psychology, and an understanding of particular experimental conditions