On Being Human ITEC 4130 Fall 2009

Understanding humans Humans evolve much more slowly than technology There are limits to human capabilities - knowing what they are helps us understand what is going on

Three Views of Humans How to model a human! Humans are interpreters/predictors - cog. psych. & AI Humans are sensory processors - sensory psych., EE & CS systems Humans are actors in environment -activity Th., ethnog., ecol. psych.

Humans as I/O machines Senses vision hearing touch smell/taste proprioception (positional feedback) requires time to propogate back to brain kinesthesia (muscle memory) instantaneous golf swing or catching a ball

Vision Two stages in vision - physical reception of the stimulus - processing and interpretation of stimulus - red arrow green arrow problem The physical apparatus: the eye - mechanism for receiving light and transforming it into electrical energy

More about the eye The eye: - the light it picks up is light that reflects from objects - images are focused upside-down on retina - retina contains rods for low light vision and cones for color vision - ganglia distribution on the retina varies by species (African plains vs tree dwellers)

Depth and Size Perception It is a complex suite of clues *visual angle indicates how much of field of view object occupies *Is your visual field circular? *Test this using a marker on the board *visual acuity is ability to perceive fine detail *predatory birds have very high visual acuity *Eagles: 600,000 cones/sq mm *Humans: 150,000 cones/ sq mm

Depth and Size Perception It is a complex suite of clues *familiar objects perceived as constant size *law of size constancy *as someone walks toward you you don’t think: Man, that guy is getting taller by the second! *Cues help perception of size and depth *Accommodation (lens stretches) *Occlusion *Motion parallax *Relative size (tied to size constancy) *Aerial perspective (atmospheric)

Brightness *Brightness is a subjective reaction to levels of light *Measured by just noticeable difference *Visual acuity increases with luminance *Pinhole camera *Reading is improved in bright light

Color Perception *Color made up of hue, intensity, saturation *Cones sensitive to color wavelengths *Blue acuity is lowest *Green acuity is highest *8% males and 1% females color blind (Red/Green confusion most freq)

XXXXX Graphical Representation at the Interface Graphical modeling and 3-D Graphical coding Graphical coding for quantitative data Color coding Color versus monochrome coding Icons

Compensation & Illusions

Reading… it’s pretty complicated “Stage” model of reading (1) visual pattern perceived (2) decoded using internal language representation (pick out the words) (3) interpreted using knowledge of syntax, semantics, pragmatics (what do these words mean?)

Perception in reading *Reading involves saccades and fixations *Saccades are rapid movements of the eye *Without them, the retina would “saturate” and you wouldn’t see anything *Fixations are the stops in that movement *Perception occurs only during fixations *Otherwise the world would be blurred! *AKA: saccade masking *Word shape is important to recognition.

Hearing Two stages in hearing - physical reception of the stimulus - processing and interpretation of stimulus -someone speaks to you -you say “what?” -but you figure out what they said before they can answer

Hearing *Provides information about environment: *Distance *Direction (but you can’t distinguish between directly in front and directly behind you!) *People can hear from 20Hz to 15kHz(I wish!) * less accurate distinguishing between high frequencies *Auditory system filters sounds *We can attend to sounds even in the presence of background noise *“cocktail party phenomenon”

Touch *Receptors in the skin: - thermoreceptors (heat and cold) but you can’t distinguish which! - nociceptors (pain) - mechanoreceptors (pressure) *Unevenly distributed across the body *Some areas more sensitive than others *fingers are more sensitive than your back

6th, 7th and 8th senses Proprioception internal awareness of your body position (Through feedback) Kinesthesis awareness of body movement (Through muscle memory) Balance vestibular organ of inner ear visual cues as to orientation awareness of body orientation through proprioception

Movement & perception Tight integration of -perception & motor planning, -movement execution -feedback proprioceptive, kinesthetic, vestibular and visual Response time = reaction time + movement time -Movement time depends on age, fitness … -Reaction time depends on modality visual: 200ms auditory: 150 ms pain: 700ms (slow and distance related)

The Box Model of Memory Sensory memories vision touch auditory Short-term/ working memory Sensory buffers are constantlyo verwritten Driven by attention Scratch-pad for temporary recall * rapid access (70ms) * rapid decay (200ms) * limited capacity (7 ± 2) Recency effect: recall of recent items best Evidence for several working memories Semantic: facts, meanings, skills, concepts, understandings… Episodic: events, time, place, emotion… Long-term Memory Episodic Semantic

The Box Model of Memory Long-term Memory Episodic Semantic Semantic memory structure -provides access to information -represents relationships between information -supports inference -associative: -recall based on meaning -gives rise to meaning-related confusions -eye witness testimony…

Attention Focused Sustained Divided Selective Alternating

Attention How to focus attention at an interface? Structure the information Others…

Consolidation Moving information from STM to LTM? Need to provide: Structure Meaning Become familiar (through rehearsal)

Forgetting Decay Information lost gradually but slowly Interference New information replaces old (retroactive) Old may interfere with new (proactive) Inhibition You can ‘choose’ to forget Example: Parking your car… You intentionally forget all but the most recent episode

Retrieval Recall * Information reproduced from memory * Can be assisted by cues, (e.g. categories, imagery, auditory input…) Recognition * Information gives knowledge that it has been seen before

Knowledge representation Declarative knowledge = knowing that Semantic networks Frames Scripts Procedural knowledge = knowing how Scripts Production rules

Semantic networks

Frame-based model of semantic memory Knowledge is organized in data structure Slots in structure are instantiated with particular values for a given instance of data...translation for CS people: frames  classes in the head; slots  variables/methods in the head)

General knowledge as frames

Script-based memory Scripts = using frames for stereotypical processes (e.g. eating in a restaurant) * used for interpreting situations * generalize episodic-memory events

Production rules Representation of procedural knowledge Condition/action rules if condition is matched, rule fires

Slips and Mistakes Slips are errors in execution of correct intention Capture errors Errors of attention Mistakes are errors in selection of goal or method for accomplishing it Errors of knowledge