Transcript Memory, Mappings, & Affordances

Memory
SENSORY
STORE
WORKING
MEMORY
LONG-TERM MEMORY
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A little experiment in memory …
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Courtesy of NASA Ames Cognition Laboratory
(http://human-factors.arc.nasa.gov/cognition/tutorials/ModelOf/memory5.html)
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Step 1: take out a blank sheet of paper and put
“List 1” on the top. Then put your pencil/pen down.
Step 2: listen to the list of words carefully.
Step 3: after the entire list is finished, you will be
instructed to write down as many of the words as
you can remember.
Step 4: check your list against the one I show you
and write the number correct at the top of the page.
Repeat steps 1 – 4 with List 2 and List 3.
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Results from an earlier experiment
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http://human-factors.arc.nasa.gov/cognition/tutorials/ModelOf/memory5.html
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Impact of memory on system design ...
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Power:
 Vast
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store of knowledge
Limitations:
 Forgetting
 Limited
working memory
 Attention
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“Just the facts” about memory ...
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Three subsystems of memory:
 Short-term
sensory store
 Working memory (short-term memory) – WM/STM
 Long-term memory - LTM
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These subsystems differ in several ways
 Capacity
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Sensory store __________________________________
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WM is ______________________________
•
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(the "magic number" 7 plus or minus 2)
LTM __________________________
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“Just the facts” about memory … (cont.)
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Differences in memory subsystems (cont.)
 Duration
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Sensory store _____________________________________
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WM _____________________________________________
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LTM _____________________________
 Codes
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Sensory store ____________________
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WM ____________________________
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LTM ____________________________
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How it works (or doesn’t) ...
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Working Memory (WM)
 A model
(from Baddeley)
Visuospatial Sketchpad
Phonological Loop
Central
Executive
• Stored in analog spatial form
• Stored in acoustical form
• From visual sensory system or
LTM
• Info kept active through
rehearsal
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WM: How it works (or doesn’t) ...
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Restrictions:
- 7 + 2 “items” of information.
 Time - 7 - 70 second “half-life”
 Capacity
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Some solutions ...
 Increase
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Create meaningful sequence already present in LTM
Experiments:
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capacity by “chunking”
Subject could recall > 20 binary digits by coding into octal
(0101111 57)
Subject could recall > 80 digits by coding into running times
(353431653  3 min, 53.4 sec mile; 3 hr, 16 min, 53 sec
marathon)
Chess masters recall board with great accuracy; "chunk" into
strategic patterns
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WM: How it works (or doesn’t) ...
 Examples
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Parsing - break up into chunks
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phone numbers, social security numbers
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Reading musical staffs ("Every Good Boy Does Fine")
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Medical school mnemonics
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Songs: constraints of rhythm, rhyme
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"We Didn't Start the Fire"
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"Joseph and the Amazing Technicolor Dreamcoat"
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Preamble to the US Constitution
 Other
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of everyday chunking:
approaches to handling WM limitations:
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Minimize load
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Visual “echoes”
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Exploit different codes (e.g., spatial, verbal, etc.)
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How it works (or doesn’t) ...
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Long-term memory (LTM)
 Types
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Semantic memory - general knowledge
Event memory
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 Basic
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Alternatively - “everything gets in”
Retrieval - depends on
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mechanisms:
Storage - through active rehearsal, involvement, or link to an
existing memory.
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Episodic - an event in the past
Prospective - remember to do something
item strength
number and strength of associations to other items
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LTM: How it works (or doesn’t) ...
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Organization of information in LTM
 Most-used
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information is semantic
retrieval depends on semantic associations
good design builds / uses appropriate semantic associations
 The
network of semantic associations around specific
topics are schemas
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Schemas involving sequences of activities are scripts
Schemas concerning how equipment and systems work are
mental models
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LTM: How it works (or doesn’t) ...
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What it means for design …
 Encourage
regular use of info
 Standardize
 Design information to be remembered
 Provide memory aids
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Memory versus knowledge “in the world”
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When do you not need to remember something?
 (Why
do you not need to remember what a penny
looks like?)
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When the knowledge is already "in the world"!
 (Because
you only need to recognize a penny - and
nothing else looks like it.)
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Knowledge “in the world”
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Affordances
Constraints
Mappings
Conceptual Models
Visible Structure
 Reveals:
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1. affordances
2. constraints
3. mappings
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Affordance
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"refers to perceived or actual properties of the
thing, primarily those fundamental properties
that determine just how the thing could possibly
be used.” (Norman, pg. 9)
 Affordances
of objects: e.g., chairs, tables, cups
 Affordances
of materials: e.g., glass, wood
 Affordances
of controls: How are things operated?
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Examples ...
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Constraints
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Those aspects of a device or material that limit
its perceived possible uses.
 Physical:
size, shape, possibilities for movement, etc.
 Semantic: meaning of the situation
 related to the notion of “conceptual models”
 Cultural:
defined by tradition, meaning within the
culture (e.g., the color red, triangular shape)
 Logical:
placement of controls, direction of
movement, etc.
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related to “mappings”
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Examples ...
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Physical constraints
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Semantic constraints
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Cultural constraints
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Logical constraints
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Conceptual Models
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Our understanding of the way things work, how
things are put together, cause & effect, etc.
 Depends
on the visibility of the system structure, the
timing of the feedback, and consistency of
cause/effect relationships
 Builds
a framework for storing knowledge about a
system or device “in the head.”
 Used
to develop explanations, recreate forgotten
knowledge, and make predictions.
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Mappings
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Making the connection between how things work
and how we think they work.
 Some
examples … (stay tuned - more in the display
design lesson!)
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Principle of Pictorial Realism: Displayed quantities should
correspond to the human's internal model of these quantities.
Congruence: The linear motion of a control and display should
be along the same axis and the rotational motion of a control
and display should be in the same direction.
Principle of the Moving Part: The direction of movement of an
indicator on a display should be compatible with the direction
of movement of an operator's internal representation of the
variable whose change is indicated.
Spatial compatibility: The spatial arrangement of displays
should be preserved in the controls.
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Your turn …
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Recall the question regarding Benjamin
Franklin given to you as homework last time.
1. List a few of the things you’ve thought of that Mr.
Franklin would be able to “figure out” in your
apartment/home.
2. Describe how Mr. Franklin is able to figure these
things out in terms of the affordances, constraints,
mappings, and visible structure.
Use the following table to help organize your answer.
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What Mr.
Franklin can
figure out
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Affordances
Physical
Constraints
Semantic
Constraints
Logical
Constraints
Cultural
Constraints
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