The Human Processing and Memory Human Computer Interaction, 2nd Ed. Dix, Finlay, Abowd, and Beale Chapter 1 Model Human Processor + Attention Recall, “purely and engineering abstraction” • Sensory store – Rapid decay “buffer” to hold sensory input for later processing • Perceptual processor – Recognizes symbols, phonemes – Aided by LTM • Cognitive processor – Uses recognized symbols – Makes comparisons and decisions – Problem solving – Interacts with LTM and WM • Motor processor – Input from cog. proc. for action – Instructs muscles – Feedback • Results of muscles by senses • Attention – Allocation of resources Overview • Will look at elements of human information processing from a slightly different orientation than “engineering abstraction” • A bit more fine grained analysis, following from psychological studies – But, it is these psychological studies from which the “engineering abstraction” is derived • 3 stage model of human memory – Iconic buffer, STM, LTM • Models of LTM • Reasoning • Problem solving 3-Stage Model of Human Memory • Sensory (here, iconic) memory – “very” short term memory – lasts 1-2 seconds, infinite capacity • Short-term memory (Working memory) – lasts ~ 18 seconds, holds 1.75 (7+/-2 items) • Long-term memory – infinite capacity; short of damage is permanent – Recall vs. Recognition (Remember vs. Know) • Retrieval cues • Will demonstrate later in class … http://www.if.uidaho.edu/~marbjm/class%202.pdf “Executive” - Attention • Central “executive” controls tasking – Pays, or allocates, attention – Bandwidth of attention is limited • Tasks that require the same resources interfere with one another • Attention is both a low-level and high-level property of vision http://www.if.uidaho.edu/~marbjm/class%202.pdf Sensory Memory: “Very” Short Term Memory • Buffers for stimuli received through senses – iconic memory: visual stimuli – echoic memory: aural stimuli – haptic memory: tactile stimuli • Examples – “sparkler” trail – stereo sound • Continuously overwritten – demo follows A Test – of Visual Iconic Memory • Will present figure briefly (~1/2 second) • Try to remember as many elements as you can • Write them down The Phenomenon • After presentation, did you continue to “see” the items? – Some purely physiological based “seeing”: • Afterimage • Bleaching of pigments • “bright, or colored, stuff” – But also, there is a more “memory-based” image (process further downstream in memory system) • Iconic memory • “dark, or veridical, stuff” • Reading from the iconic buffer Reading from the Iconic Buffer, 1 • Typically can list 3 – 7 items named • Short lived visual, or iconic, buffer – holds the image for a second or two • Read images and place in STM Set of miscellaneous symbols – 3-stage model • Can get about 5-7 items until run out of short term (working) memory capacity • Limitation of 5-7 comes from: – Decay of iconic memory Useful Visual Field of View Visual Search or Monitoring – Rate can read from visual buffer Strategy – Capacity of working memory Eye Movement Control • In each fixation between saccadic eye movements, image of world captured Reading from the Iconic Buffer, 2 • Again, Limitation of 7 comes from: – Decay of iconic memory – Rate can read from visual buffer – Capacity of working memory • From each image, Set of miscellaneous symbols – brain must identify objects, – match them with objects previously perceived, and – take information into working memory for symbolic analysis • Search light model of attention (for vision) Useful Visual Visual – Visual information is acquired by pointing Field of View Search or Monitoring Strategy fovea at regions of visual field that are interesting Eye – Then using a scanning process in which Movement Control objects are read from an image buffer from more extensive processing Attention • Spotlight metaphor – Spotlight moves serially from one input channel to another – Can focus attention (and perceptual processor) on only one input channel at a time • Location in visual field, voice in auditory field, …, anything • Visual dominance: – Easier to attend to visual channels than auditory channels • All stimuli within spotlighted channel are processed in parallel – Whether you want to or not – Can cause “interference” - demo Say the Colors of the Words • Easy enough – didn’t take too long Say the Colors of the Words • Took longer … Stroop effect • Choose secondary characteristics of display to reinforce message Again, Human Memory Stages • Sensory (here, iconic) memory – lasts 1-2 seconds, infinite capacity • Short-term memory (Working memory) – lasts ~ 18 seconds, holds 1.75 (7+/-2 items) • Long-term memory – infinite capacity; short of damage is permanent – Recall vs. Recognition (Remember vs. Know) • Retrieval cues http://www.if.uidaho.edu/~marbjm/class%202.pdf Short-term memory (STM) • “Scratch-pad” (or buffer) for temporary recall – rapid access ~ 70ms – rapid decay ~ 200ms – limited capacity - 7± 2 chunks • Chunking, recoding, etc. – affects amount of information retained, entering LTM Examples - Chunking 212348278493202 0121 414 2626 HEC ATR ANU PTH ETR EET 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 (episodes): Serial memory of events – Semantic (“meanings”): Structured memory of facts, concepts, skills • Semantic LTM derived from episodic LTM LTM – Models of Semantic Memory • Semantic memory structure – Provides access to information – Represents relationships between bits of information – Supports inference • Many models, theories, accounts, schemata proposed • Semantic network model (example next slide): – Inheritance – child nodes inherit properties of parent nodes – Relationships between bits of information explicit – Supports inference through inheritance • Other Models (examples follow): – Scripts, frames, production rules LTM - semantic network Models of LTM - Frames • Information organized in “memorial 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 • 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 Models of LTM - Production Rules • Representation of procedural knowledge. • 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 • LTM much studied in psychology: • 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 • Structure, meaning and familiarity – information easier to remember 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 …! • Also, affected by emotion – can subconsciously `choose' to forget 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 Thinking – Cognitive Processing • Humans reason, process information, like, well, humans – Recall, any theory is an abstraction and, thus, captures some elements of phenomenon, and misses others – Question is … • Is the account (theory, model) useful in the context and for the purpose for which it is used? • Basic forms of reasoning, or, forming inferences, are useful in understanding broad outlines of human cognition – Deduction – Induction – Abduction • Problem solving – Gestalt – Problem Space – Analogy – Skill acquisition Induction vs. Deduction • Induction: make observations first, then draw conclusions – organized data survey (structured analysis, visualization) of the raw data provide the basis for the interpretation process – the interpretation process will produce the knowledge that is being sought – experience of the individual scientist (the observer) is crucial – important: selection of relevant data, collection method, and analysis method – data mining is an important knowledge discovery strategy here – ubiquitious data collection, filtering, classification, and focusing is crucial • Deduction: formulate a hypothesis first, then test the hypothesis – via experiment and accept/reject – data collection more targeted than in induction – only limited data mining opportunities Mueller, 2003 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 • Induction: – Generalize from cases seen to cases unseen • e.g. all elephants we have seen have trunks - therefore all elephants have trunks. – Unreliable (but useful): • can only prove false not true • Abduction: – Reasoning from event to cause e.g. Sam drives fast when drunk. If I see Sam driving fast, assume drunk. – Unreliable: • can lead to false explanations Problem solving - Briefly • Process of finding solution to unfamiliar task using knowledge • Several theories • Gestalt – Problem solving both productive and reproductive – Productive draws on insight and restructuring of problem – Attractive but not enough evidence to explain `insight' etc. – Move away from behaviourism and led towards information processing theories Problem solving (cont.) • Problem space theory – Problem space comprises problem states – Problem solving involves generating states using legal operators – Heuristics may be employed to select operators e.g. means-ends analysis – Operates within human information processing system e.g. STM limits etc. – Largely applied to problem solving in well-defined areas e.g. puzzles rather than knowledge intensive areas Problem solving (cont.) • Analogy – analogical mapping: • novel problems in new domain? • use knowledge of similar problem from similar domain – analogical mapping difficult if domains are semantically different • 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 Individual Differences • Long term – Sex, physical and intellectual abilities • Short term – Effect of stress or fatigue • Changing – Age • Dix says ask: – Will design decision exclude section of user population? – (or, more generally) How does design differentially affect sections of the population? • Universal Usability - Model Human Processor + Attention - Similar to Ware (2004) Model • Sensory store – Rapid decay “buffer” to hold sensory input for later processing • Perceptual processor – Recognizes symbols, phonemes – Aided by LTM • Cognitive processor – Uses recognized symbols – Makes comparisons and decisions – Problem solving – Interacts with LTM and WM • Motor processor – Input from cog. proc. for action – Instructs muscles – Feedback • Results of muscles by senses • Attention – Allocation of resources A Model of Perceptual Processing Quick Overview What we do is design information displays! • An information processing (the dominant paradigm) model – “Information” is transformed and processed • Physical light does excite neurons, but at this “level of analysis” consider information – Gives account to examine aspects important to visualization • Here, clearly, many neural subsystems and mapping of neural to ip is pragmatic – In spirit of visualization as evolving discipline, yet to develop its theories, laws, … • Stage 1: Parallel processing to extract low-level properties of the visual science • Stage 2: Pattern perception • Stage 3: Sequential goal-directed processing Stage 1: Parallel Processing to Extract Low-level Properties of Visual Scene • (Very first) neurons fire • Visual information 1st processed by – large array of neurons in eye – primary visual cortex at back of brain • Individual neurons selectively tuned to certain kinds of information – e.g., orientations of edges or color of light – Evoked potential experiments • In each subarea large arrays of neurons work in parallel – extracting particular features of environment (stimulus) Stage 1: Parallel Processing to Extract Low-level Properties of Visual Scene • At early stages, parallel processing proceeds involuntarily – Largely independent of what choose to attend to (though not where look) • Is rapid, – If want people to understand information fast, should present in way so is easily detected by these large, fast computational systems in brain • Stage 1 processing is: – Rapid and parallel – Entails extraction of features, orientation, color, texture, and movement patterns – “transitory”, only briefly held in iconic store – Bottom up, data-driven Stage 2: Pattern Perception • Rapid processes • Divide visual field into regions and simple patterns, e.g., – Continuous contours – Regions of same color – Regions of same texture – … • “Active”, but not conscious processes • Specialized for object recognition – Visual attention and memory • E.g., for recognition must match features with memory – Task performing will influence what perceived – Bottom up nature of Stage 1, influenced by top down nature of Stage 3 Stage 2: Pattern Perception • Specialized for interacting with environment – E.g., tasks involving eye-hand coordination • “Two-visual system hypothesis” – One system for locomotion and eye-hand coordination • The “action system” – One system for symbolic object manipulation • The “what system” • Characteristics: – Slow serial processing – Involvement of both working (vs. iconic) and long-term memory – Both bottom up and top down • More emphasis on arbitrary aspects of symbols than Stage 1 • Top-down processing – Different pathways for object recognition and visually guided motion Stage 3: Sequential Goal-Directed Processing • At highest level of perception are the objects held in visual memory by demands of active attention • To use an external visualization, we construct a sequence of visual queries that are answered through visual search strategies • Only a few objects can be held at a time • They are constructed from available patterns providing answers to the visual queries Stage 3: Sequential Goal-Directed Processing • They are constructed from available patterns providing answers to the visual queries • E.g., if use a road map to look for a route, the visual query will trigger a search for connected red contours (representing major highways) between two visual symbols (representing cities) • Are other subsystems, as well – Visual object identification process interfaces with the verbal linguistic subsystems of the brain so that words can be connected to images – The perception-for-action subsystem interfaces with the motor systems that contril muscle movements End • .
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