On Being Human ITEC 4130 Fall 2009. Understanding humans Humans evolve much more slowly than technology There are limits to human capabilities - knowing.

On Being Human

ITEC 4130Fall 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

systemsHumans are actors in environment

-activity Th., ethnog., ecol. psych.

Humans as I/O machines

Sensesvisionhearingtouchsmell/tasteproprioceptionkinesthesia

VisionTwo stages in vision- physical reception of stimulus- processing and interpretation of stimulus

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 PerceptionIt 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

Depth and Size PerceptionIt 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)

Graphical Representation at the

InterfaceGraphical modeling and 3-DGraphical coding

Graphical coding for quantitative data

Color codingColor versus monochrome coding

Icons

Compensation & Illusions

http://blindspottest.comhttp://en.wikipedia.org/wiki/Image:Gradient-optical-illusion.svghttp://en.wikipedia.org/wiki/Same_color_illusionhttp://en.wikipedia.org/wiki/Grid_illusionhttp://en.wikipedia.org/wiki/Ponzo_illusionhttp://en.wikipedia.org/wiki/Image:Revolving_circles.svg

Reading… it’s pretty complicated

“Stage” model of reading(1) visual pattern perceived(2) decoded using internal language representation(3) interpreted using knowledge of syntax, semantics, pragmatics

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!

* Word shape is important to recognition.

Hearing* Provides information about environment:

* Distance* Direction

* People can hear from 20Hz to 15kHz* 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)- 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

Proprioceptioninternal awareness of your body position

Kinesthesisawareness of body movement

Balance vestibular organ of inner earawareness of body orientation w.r.t. vertical

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: 200msauditory: 150 mspain: 700ms (slow and distance related)

The Box Model of Memory

Sensory memoriesvisiontouch

auditory

Short-term/workingmemory

Long-termMemory

Sensory buffersareconstantlyoverwritten

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

Declarative memory:semantic + episodic

Semantic: facts, meanings, skills, concepts, understandings…Episodic: events, time, place, emotion…

The Box Model of Memory

Long-termMemory

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

FocusedSustainedDividedSelectiveAlternating

Attention

How to focus attention at an interface?Structure the informationOthers…

Consolidation

Moving information from STM to LTM?

Provide:Structure Meaning Become familiar (through rehearsal)

Forgetting

DecayInformation lost gradually but slowly

InterferenceNew information replaces old (retroactive)Old may interfere with new (proactive)

InhibitionYou can ‘choose’ to forgetExample:

Parking your car…You intentionally forget all but the most

recent

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

Knowledge representation

Declarative knowledge = knowing thatSemantic networksFramesScripts

Procedural knowledge = knowing howScriptsProduction 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 memoryScripts = 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 rulesif condition is matched, rule fires

Slips and Mistakes

Slips are errors in execution of correct intention

Capture errorsErrors of attention

Mistakes are errors in selection of goal or method for accomplishing it

Errors of knowledge