UGS 302 – Usability and UCD - Scientific Underpinnings - Memory and Cognition

R. G. Bias | School of Information | UTA 5.424 | Phone: 512 471 7046 | [email protected]

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UGS 302 – Usability and UCD

- Scientific Underpinnings- Memory and Cognition

Day 5


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Objectives

After this class you will be able to (it is my hope!):

• Explain the human memory system• Explain how psychologists gathered data to infer the

two-stage theory of memory• Explain some aspects of the psychology of reading• Explain how perceptual and cognitive psychology

influence HCI designs• Have an excellent memory for “VAM”• Discuss the importance of designing systems to match

the human.


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Whole point . . .

• Let’s design systems to fit people instead of the other way around.


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Human Information Processing

• How do human beings take in and process information?– Sensory psychology – how humans transform physical

energy (e.g., light and sound waves) into sensory signals to and in the brain.

– Perceptual psychology – how humans interpret these sensory signals as perceptions.

– Cognitive psychology – how humans think about these perceptions, and previous experiences, and their own mental creations, and . . .

– Psycholinguistics – The psychology of language -- what goes on between the time I have a thought and you have the same (or similar!) thought, whether I say it or write it.


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What do we know about humans?

– In the physical realm: Anthropometry.– These days we’re more interested in the cognitive

realm.– Question: Can you remember a 30-digit number?– I say that you can, right now, without practice, seeing

it only once, for 1 second, with no time to rehearse.


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3333333333333333333333333333333


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Experiment 1

Instead of numbers, I’ll present CVC (consonant-vowel-consonant) strings -- like “NEH”.

10 CVCs, one at a time.

Presented visually.

Don’t have to remember them in order.

Pencils down.

Ready?


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BOVNAZTOLRIJDIHRENWUKCAQGOCMEB


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BOVNAZTOLRIJDIHRENWUKCAQGOCMEB


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Experiment 2

•Now, 10 new CVCs. •Same task -- recall them.•This time, after we read the 10th item, we’ll all count backwards from 100 by 3s, aloud, together.•Then when I say “Go,” write down as many of the 10 CVCs as you can.•Pencils down.•Ready?


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VAMLUNXOPREHWIVCITJEGKUCZOBYAD


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VAMLUNXOPREHWIVCITJEGKUCZOBYAD


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Experiment 3

• Same as Experiment 2.

• Yet 10 more CVCs.

• Backwards counting.

• Don’t have to recall them in order.

• Pencils down.

• Ready?


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GEPTIV

WOHLUPMAZSEXKOLRUCNIDBIR


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GEPTIV

WOHLUPMAZSEXKOLRUCNIDBIR


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So?

• So, the answer to “Can you remember a 30-digit number?”, is . . . It depends. On what?– Whether you hear or see the number.– Whether the number is masked.– Whether you have time to rehearse.– Whether you can “chunk” the numbers.– If there are any intervening tasks.– How meaningful the number is.– WHAT the number is.

So, what’s a usable interface?It depends.


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Psycholinguistics

• The psychology of language.

• What goes on from the time I get an idea until you have the same idea,– Whether I speak my idea (speech

production, auditory science, speech perception)

– Or write my idea (motor movements, visual system, reading)


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The Psychology of Reading

• Except for fairly rare cases of “phonetic symbolism” (onomatopoeia) words have no inherent meaning.– (And rarer cases of “orthographic

symbolism”!!)

• So, READING is the interpreting of words, the acts that go on to impose meaning, from within, on external visual stimuli.


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Some facts about reading

• Eyes of the mature reader move rhythmically across the page (from left to right).

• Eye movement consists of fixations, saccades, regressions, and return sweeps.

• No information is taken in during saccades (10-25 msec), regressions (same duration), or return sweeps (40 msec).

• During fixation (250 msec) a visual pattern is reflected onto the retina.

• Span of perception = amount of print seen during a single fixation.

• Span of perception = 12 letter spaces for good readers, 6 for poor readers.


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More facts

• Span of recognition – 1.21 words for senior high, 1.33 words for college readers.

• So, 7 to 8 fixations per line of print.• As content gets tougher, duration of fixations, not number,

changes (increases).• Regressive movements aren’t systematic. Used when attention

is faltering.• College readers have 1 regressive movement per 3 or 4 lines of

print. Immature readers have 3 or 4 regressions per line.


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Iconic Memory

• Earlier I mentioned a two-stage memory process – STM and LTM.

• A third stage, Iconic Memory: The unidentified, “pre-categorical” pattern of lines, curves and angles; formed in about 100 msec.

• Icon can hold up to 20 letter spaces.• Pattern recognition routines are applied to the lines, curves.• It takes about 10 – 20 msec to read each letter out of the iconic

memory.• Neural signal takes about 30 msec to go from the retina to the

visual cortex.


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Iconic Memory (cont’d.)

• At some point, thanks to pattern recognition routines, letters are read out.

• Letters are transformed into abstract phonemic representations.• The abstract phonemes are used to search the mental lexicon.• About 300 msec after the eye has fallen upon the page, the first

word is “understood,” i.e., placed in Primary Memory (STM, Working Memory).

• Syntactic and semantic rules are applied to gain the meaning of the sentence.


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How do you know, Randolph?

• Psycholinguists employ a variety of methods to acquire this data about human behavior.

• One question: Why do we think readers routinely transform the visual representation into a phonological representation?– Cognitive economy – all (healthy) new readers

come to the task as skilled hearers.– “I thought you said something about data?”


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Rubenstein et al. (1971)

• Used a lexical decision task (word/nonword?).• Two types of nonwords – homophonous (with real

words), like burd and nonhomophonous like rolt. Equally “wordlike.”

• Longer latencies for burd.• Similarly, longer for real homophones like meat.• Pointed to “false matches” in the mental lexicon.


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More Data

• McCusker et al. (1977) proofreading experiment– Homophonous typos (e.g., furst) went undetected

more often than nonhomophonous typos (e.g., farst).

• Gough and Cosky (1977) used the Stroop task.– Nonwords homophonous with color words (e.g,. bloo) led to

more interference than control words (e.g., blot) or nonwords nonhomophonous with color words (e.g., blop).

• I found readers took longer to process words with irregular “spelling-to-sound rules” (e.g., pint) than words with regular rules (e.g., hint) (Bias, 1978).


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The Point

• The reasons for this somewhat esoteric discourse on the psychology of reading are:– To communicate the complexity that is

human information processing– The illustrate the ways scientists go about

answering questions about info processing– To sensitize you to the sorts of things

known about human behavior


iUpcoming

• This Thursday – more presentations.

• Also, remember:– Bring to class a URL showing a good and

poor WEB design. (Actually, send me the URLs in advance of class – say, by 1/29/2013, midnight tonight, and I’ll have it ready to go.)

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Documents

UGS 302 – Usability and UCD - Scientific Underpinnings - Memory and Cognition