Download The Design of Everyday Things-Part 3

Unit 3
The Design of
Everyday Things
Professional
Development II
PSYC 4170
Part 3: Knowledge in the
Head and in the World
Michael J. Kalsher
Every day , we are confronted with objects, devices, and
services that require specific actions to operate, repair and
use them. Our knowledge is often incomplete, ambiguous,
or wrong, yet we still get through these situations just fine.
Q: How does this happen?
A: We generally follow a
distributive approach in which we
combine knowledge-in-the-head
(KITH) with knowledge-in-theworld (KITW) as demanded by
the situation.
•This minimizes the amount of material we must learn or
retain in memory, as well as the completeness, precision,
accuracy, and depth of the learning.
Differentiating kinds of knowledge
Knowledge-in-the-head (KITH):
Information in memory from experience.
Note: In this unit we review aspects of memory that relate to the design of usable products.
Knowledge-in-the-world (KITW):
Information in the external environment. As it pertains to
product design, this includes user manuals, product
labeling, and informational cues inherent in or on the
product itself (e.g., lettering on the keys of your
smartphone or computer keyboard).
Differentiating Forms of KITH (memory)
Knowledge of:
Refers to knowledge or memory of facts and
rules (also termed declarative knowledge).
NOTE: Doesn’t mean the facts are complete or true or that people will follow the rules. Declarative
knowledge is also termed explicit memory. Main issue with KITH pertains to organization.
Knowledge how:
Refers to the knowledge that enable a person to perform
skilled behaviors (e.g., riding a bike, returning a serve in tennis,
moving your tongue appropriately to articulate spoken words).
Also termed procedural knowledge or muscle memory.
NOTE: Procedural knowledge is actually a form of implicit memory. It is difficult to write down and
difficult to teach. Best taught by demonstration and best learned through practice.
Precise behavior can emerge from imprecise
knowledge for the following reasons:
1.Knowledge is both in the head and in the world. Taskrelevant KITH is good to have, but successful task behavior can
be achieved through use of external information sources.
2.Great precision isn’t required. Successful behavior is
possible if the combined KITH and KITW is sufficient to
distinguish appropriate choices/behaviors from all others.
3.Natural constraints exist in the world. The world has many
natural (and manufactured) physical (and cognitive/procedural)
constraints that restrict the number of possible behaviors.
4.Knowledge of cultural constraints and conventions exists
in the head. Such constraints are learned artificial restrictions on
behavior that reduce the set of likely actions, in many cases
leaving only one or two possibilities.
Can you pick the real one?
Nickerson, R.S., and Adams, J.J. (1979). Long-term memory for a common object. Cognitive Psychology, 11, 287-307.
When Precision is Unexpectedly Required
• Combination of KITH + KITW is usually sufficiently
precise to handle most day-to-day decisions.
• But … when unexpected events occur, the
combination may not be enough.
• Example: Confusions involving the Susan B. Anthony
dollar.
Susan B. Anthony Coin
Susan B. Anthony (SBA) coin
legislation was approved in 1978.
The SBA represented a downsizing
of the larger Eisenhower dollar coin
… but
– The SBA coin closely resembled the U.S. quarter in size (only
2.2 mm wider) and was confused with it.
– Users had representations in their memories that were
sufficiently precise to distinguish among coins they were already
accustomed to using. People typically maintain only partial
descriptions of things to be remembered.
– Then, why don’t people confuse $1 and $20 bills?
Role of Constraints in Simplifying Memory
• Before widespread literacy, traveling performers recited
poems thousands of lines long. How did they do this?
• External constraints control the permissible choice of
words, which in turn, dramatically reduces memory load.
• Albert Bates Lord – classic study of memory for epic
poetry in the mid-1990s
– Identified Yugoslavian groups that followed oral traditions.
– Learned epic poems & went village-to-village reciting them.
– Presentations differed, but were the same in ways that matter
to listeners: They told the same story, expressed the same
ideas, and followed the same rhyme and meter.
Role of Constraints in Simplifying Memory:
A Summary
• External constraints control the permissible choice of
words and dramatically reduce memory load.
• Research shows that:
- while original and subsequent recitations are not identical,
they are similar in ways that matter to listeners.
- Reciters tend to tell the same story, express the same
ideas, and follow the same rhyme and meter.
- The idea that people should be able to recite lengthy poems
word-for-word is a recent expectation, triggered by the
widespread availability of printed texts.
- Physical and cultural constraints and ordering help to
reduce the cognitive/memory load.
Constraints Simplify Memory:
A Research Example
Task 1
– Subjects are told: “I am thinking of three words: one means
a mythical being, the second is the name of a building
material, and the third is a unit of time.”
– There are no constraints, so it is not surprising there is no
consistency among subjects’ responses.
Task 2
– Subjects are told: “I am thinking of three words: one
rhymes with post, the second with eel and the third with ear.
What words am I thinking of?”
– Again, the lack of constraints in the problem results in
significant variability in subjects’ responses.
Task 3
-Subjects are asked the following questions:
• What word means a mythical being and rhymes with post?
• What word names a building material and rhymes with eel?
• What word is a unit of time and rhymes with ear?
Here the joint specification effectively constrains word
choice. Nearly all subjects’ responses are: ghost,
steel, and year, respectively.
– Many everyday examples in which natural
constraints limit the possible action choices.
• Repairing and/or reassembling mechanical devices
• Ordering and physical characteristics (bolts, screws, nuts)
The Structure of Memory: STM
Short-term Memory (also termed “working memory”)
– Information that is currently being thought about (what we’.
– Limited (approximately 5-7 “chunks”).
– Information in working memory decays rapidly unless
actively rehearsed.
Brown-Peterson paradigm
– Showed that without
active rehearsal, STM
degrades exponentially
to an asymptote.
STM: Engineering Design Implications
• Minimize STM load
– Minimize number of items operators need to retain in working memory during
task performance
• Provide redundant cues (e.g., visual + auditory or tactile)
• Exploit chunking
- Optimize physical chunk size (Optimal chunk size is 3 or 4 numbers or letters)
- Use meaningful sequence (letters more meaningful than numbers)
- Keep numbers separate from letters (e.g., license plate sequencing)
• Minimize Confusability
– More confusion when lists sound similar; physical distinctions reduce confusion
• Exploit different working memory codes
– Working memory retains 2 qualitatively different types of information: visual
spatial and verbal phonetic
– Each system seems to process info somewhat independently
– If one code is being used, it will be interrupted more by processing that same
type of information than by processing information in alternative code
The Structure of Memory: LTM
Declarative (explicit) memory: Refers to memory of
facts and events (that can be consciously recalled).
-
Episodic: recall of specific personal experiences.
Semantic: recall of factual information (Jeopardy knowledge)
Implicit memory: Implicit and skill-based knowledge
that is usually acquired and used unconsciously.
- Procedural memory: Also termed “muscle memory”, this
form of implicit memory helps to explain how people learn how
to ride a bike, and do so many years later even in the absence
of practice. Also includes tacit knowledge—knowledge we
acquire through experience that we don’t realize we have.
Theories of LTM
• Levels of Processing
• Paivio’s Dual Code Theory
Levels of Processing
Memory strength depends on the strength of associations
made between to-be-remembered items and and existing
information in LTM. Deep processing is superior to other
more superficial types of processing.
– Participants in an study employing the incidental memory
paradigm in which they are unaware that their memory will be
tested later.
– They are given one of 3 tasks involving, say—an apple
Surface task (Is it red? Is it small?)
Phonological task (Does it rhyme with chapel?)
Semantic task (Is it edible? Is it a Fruit? Is it good for you?)
• People remember the information best when engaged in
semantic (deeper) processing, as compared to superficial
processing.
Paivio’s Dual Code Theory
• Based on the fact that our memory for pictures is better
than our memory for words.
– Words are coded in memory via a verbal code
– Pictures are coded visually (by their appearance) and
verbally.
• Dual coding theory helps explain why concrete words
(chair) are easier to remember than abstract words (honor).
– Concrete words can easily be transformed to a pictorial
image, whereas abstract words cannot be transformed as
easily.
Long-Term Memory:
How Information is Organized
Information is organized around central concepts
Schema: term used to describe a person’s knowledge
structure about a particular topic.
-- e.g., The knowledge structure I have about my role as a
college professor.
– Schemas describing an activity sequence are called scripts
(e.g., your morning routine).
Mental Models are a type of schema that describes our
understanding of systems and their components, how a
system works, and how to use it.
Mental models that are shared by a large group of people
are termed population stereotypes.
How do people use their memory and retrieve
knowledge? Memory for Arbitrary vs. Meaningful Things
Arbitrary Knowledge: memory of things that have no
underlying meaning or structure (e.g., letters of the
alphabet and their ordering; names of people).
1. Requires rote learning; considerable time and effort.
2. When problems occur, the memorized sequence of
information doesn’t necessarily contain hints of what has gone
wrong or how to fix the problems.
3. When things in the world have a sensible structure, they
generally correspond to knowledge we already have in
memory and so can be understood, interpreted and integrated
with previously-stored knowledge.
Conceptual Models and Meaning
1. Norman’s colleague had difficulty
remembering how to use the turn signal on
the left handlebar of his motorcycle.
2. Moving the switch forward signaled a right
turn; backward, a left turn. He thought it
should work opposite and frequently made
mistakes.
3. He solved the problem by reinterpreting
the action in terms of how the handlebars
move during a turn. For a left turn, the left
handlebar moves backward, for a right turn it
moves forward.
When the motion of the switch seemed arbitrary it was difficult for him to learn;
once he invented a meaningful relationship it was easy to remember. Providing
meaningful structures makes memory less important.
LTM: Engineering Design Implications
1.
Encourage regular use of information to increase
frequency (of use) and recency.
2.
Encourage active verbalization or reproduction of the
to-be-remembered information (deep processing to form
strong associations is best!).
3.
Standardization can reduce memory load
- Results in development of strong yet simple schemas and mental
models that are applicable to a wide variety of circumstances.
4.
Use memory aids
-
Design appropriate “KITW” so people don’t have to rely on “KITH”
Strategic use of memory mnemonics (pegword; method of loci)
Long-Term Memory:
Implications for Design
5. Carefully design to-be-remembered information
- Should be meaningful (as compared to arbitrary) and
semantically associated with other information stored in LTM
- Use concrete rather than abstract words when possible
- Use distinctive concepts/information to reduce interference
- Information should be well-organized
- An item should be able to be guessed based on other
information to take advantage of top-down processing
- Limit technical jargon
6. Design to support development of correct mental models
–
Apply the concept of visibility: users should be able to
determine the state of a device and the alternatives for
action immediately.
Approximate Models:
Well-learned skills bypass the
need for conscious oversight and control
Converting temperatures between Fahrenheit and Celsius
It is now 55 degrees Fahrenheit outside. What is it in Celsius?
Precise (Paper-and-Pencil) Approach
-∘ C = (∘F – 32) x 5/9 = (∘55 – 32) x 5/9 = 12.8 ∘
Simplified Approach (good enough if my concern is whether to wear a
sweater or not)
-∘ C = (∘F – 30) / 2 = 25 / 2 = 12.5 ∘
KITH and KITW: Tradeoffs
Knowledge in the World
Knowledge in the Head
Information readily and easily available
whenever perceivable
Material in working memory is readily
available. Otherwise considerable search
and effort may be required
Interpretation substitutes for learning.
Requires learning, which can be
Difficulty in interpreting KITW depends upon considerable. Learning is easier if there is
the skill of the designer.
meaning or structure or a good conceptual
model.
Slowed by the need to find and interpret the
knowledge.
Can be efficient, especially if so welllearned that it is automatic.
Ease of use at first encounter is high.
Ease of use at first encounter is low.
Can be ugly and inelegant, especially if
there is a need to maintain a lot of
knowledge. This can lead to clutter. Here is
where the skills of the graphics and
industrial designer play major roles.
Nothing needs to be visible, which gives
more freedom to the designer. This leads to
cleaner, more pleasing appearance—at the
cost of ease of use at first encounter,
learning, and remembering.