The Human
Mar 31, 2015
The Human
Cognitive Psychology
In order to design something for someone, we need to understand the capabilities and limitations of that person How humans perceive the world around them How humans store and process information and
solve problems How humans physically manipulate objects
Models of the User
Model Human Processor
Our Model
Cognitive System
PerceptualSystem
MotorSystem
CPU
I/O
Memory
Human I/O Channels
Input via the senses Sight Hearing Touch Taste Smell
Output via motor control Limbs (feet?) Fingers Eyes Head Voice
The Human Eye
Cornea and lens focus light onto the… Retina, which contains Photoreceptors:
rods - brightness cones - color (red, green and blue)
Ganglions, which are nerve cells that... (X-cells) - detect pattern (Y-cells) - detect movement
Fovea - center of vision
Visual Perception
Depth Size constancy - smaller means farther Occlusion - obstructed means farther Texture - finer means farther
Brightness - contrast (and flicker) Color
150 hues 7 million shades
Reading
Saccades - eye scans forward Fixations - eye is still
Perception happens 94% of the time
Regressions - eye looks back (complex) 9pt,12pt equally legible Books faster than computers
Hearing
Auditory canal -> eardrum -> ossicles -> cochlea -> cilia
Sound parameters Pitch - frequency Loudness - amplitude Timbre - waveform of sound
Stereo location of source Cocktail party effect
Touch
Haptic perception Skin receptors
thermoreceptors - heat, cold nociceptors - intense pressure, heat, pain mechanoreceptors - pressure
Two point test - haptic accuity
Movement
Kinesthesis - Do you know where your limbs are? Reaction time vs. accuracy Fitts’ law:
Movement time = a + b log (distance/size + 1)
Memory
Three kinds of memory sensory short term long term
Sensorymemory
AttentionWorkingmemory
RehearsalLong-termmemory
Sensory Memory
Human Cache Memory Iconic memory - visual
Persistence of vision .5 seconds
Echoic memory - aural Haptic memory - touch Arousal - level of interest or need
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Short Term Memory
Human DRAM (Dynamic random-access memory) 70ms access time 200ms refresh time Size: 7 +/- 2 items
digits chunks words
Recency effect - last is best
Fun with Working Memory
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456 295 1413
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Long Term Memory
The Human World-Wide Web Two types
episodic - events, organized temporally semantic - facts, organized associatively
Representations semantic nets frames scripts
SEMANTIC NETWORK
Frames
Extends semantic nets to include structured hierarchical information
University
Fixed: type of school
Default: has colleges
Variable: public/private
Universitas Gunadarma
Fixed: type of University
Default: public
Variable: campus
Scripts
Stereotypical information Entry conditions: need job, have money Result: educated, less money Props: books, schedule, new car Roles: instructor talks, students listen Scenes: classroom, dorm Tracks: internships, apprenticeships
Processes
How does information get from short term memory into long term memory? Total time hypothesis - hit the books Distribution of practice effect - don’t cram Meaning - concrete better than abstract
faith age cold tenet quiet logic idea value past boat tree cat child rug plate gun flame head
Structure, familiarity and concreteness
How We Forget Decay
Logarithmically - forget most early Jost’s Law - if two equally strong memories at a given
time, then the older is more durable. Interference
retroactive interference - old phone number (later learning) proactive inhibition - driving to the old house (previous memories) emotion - good old days, forget the mundane
Information Retrieval
How do we recall details? Categorization Visualization 1 roti
2 sepatu
3 pohon
4 pintu
5 sarang
6 tongkat
7 surga
8 pagar
9 teh
10 ayam
Real Intelligence
How is information processed and manipulated? Animals - receive and store info, but do not
process it as well as humans Computers - receive and store info better then
humans, but do not process it as well as humans
Human Intelligence
Humans use information to Reason & solve problems Even if the info is partially missing or completely
absent!Human thought is
conscious & self-aware capable of imagination
Reasoning
Inferring missing information Deductive - conclusions Inductive - generalizations Abductive - suppositions
Deductive Reasoning
If A then B A. Therefore B not B, therefore not A.
• Telepon berdering pada saat saya mandi Bila saya mandi, maka telepon berdering Bila telepon berdering, saya mandi Bila saya tidak mandi?
Inductive Reasoning
Specific A has property B then all A is B Gajah memiliki belalai Komputer lambat Lelaki memiliki kumis Perempuan memakai anting
Abductive Reasoning
From fact to the action that caused it Mata bengkak Tanah Becek Helai rambut panjang di kemeja
Problem Solving
Using knowledge to find a solution Gestalt theory Problem space theory Analogy
Gestalt Theory
Finding new solutions Reproductive problem solving
Learned behavior, trial and error Behavioralist Fixation
Productive problem solving Invention, innovation, insight
Problem Space Theory
Mapping out a solution step by step Problem states, goal state, current state Legal state transition operators Heuristics, e.g. means-ends analysis Examples
Games: 15 puzzle, chess Tasks: Setting the VCR clock Life (emphasis on “legal”)
Analogy
Applying one solution to a different problem Analogical mapping Purely productive reasoning is hard (10%) Drawing analogies is easier (80%) Existing solution “semantically close” to problem
domain
Skill Acquisition
Solving problems that are not completely new e.g. Chess
Same goal (different goal states) Same transitions Different “skills”
Problem groups novices group problems superficially experts group problems conceptually
ACT Skill Acquisition Model
How is skill acquired?
General rules
Specific rules
Tuned rules
Proceduralization
Generalization
Errors
How do we make mistakes? Slips - change in context of skill Mental models - incorrect interpretation of the
evidence
Design
How do we use what we know about humans to make better user interfaces? Guidelines Models Evaluation