Introduction to Memory laura leventhal. Reference Chapter 14 Chapter 14.

Introduction to MemoryIntroduction to Memory

laura leventhallaura leventhal

Reference

Chapter 14Chapter 14

Types of Memory-OverviewTypes of Memory-Overview

Sensory memorySensory memory Short-term memoryShort-term memory Working storageWorking storage Long-term memoryLong-term memory

Sensory MemorySensory Memory

A sensory memory for each input A sensory memory for each input channelchannel

Echoic MemoryEchoic Memory Iconic MemoryIconic Memory

Short-Term MemoryShort-Term Memory

Information from the outside world Information from the outside world enters the cognitive systementers the cognitive system

Scratch-padScratch-pad Fast access, fast decayFast access, fast decay Limited capacity Limited capacity

Working StorageWorking Storage

A little more permanent that STMA little more permanent that STM Less permanent than LTMLess permanent than LTM Things like “where did I park my car” or Things like “where did I park my car” or

a phone number remembered with a phone number remembered with rehersal.rehersal.

Using info about STM in Using info about STM in Interface DesignInterface Design

What can we do with this information? What can we do with this information? Even with the short overview, we can Even with the short overview, we can

get some clues about why so many get some clues about why so many interfaces are failures for the majority of interfaces are failures for the majority of their users.their users.

What makes an expert?What makes an expert?

Many thingsMany things One ability experts have over novices is One ability experts have over novices is

the ability to form and use longer and the ability to form and use longer and more complex CHUNKS.more complex CHUNKS.

ChunksChunks

Chunks guide visual perception. Chunks guide visual perception. When we see things in the visual field, When we see things in the visual field,

the way that we group is based on the the way that we group is based on the way that we chunk visual inputsway that we chunk visual inputs

How we group visual info is based on How we group visual info is based on our experience. our experience.

Capacity of STMCapacity of STM

Measured in ChunksMeasured in Chunks• About 5 - 7 chunksAbout 5 - 7 chunks• ““The magic number 7”The magic number 7”

Chunking ExampleChunking Example

We all can read English. Which of the We all can read English. Which of the following two telephone numbers is following two telephone numbers is easier to remember?easier to remember?

1-827-549-48901-827-549-4890 1-300-EAT-FISH1-300-EAT-FISH Which URL?Which URL?

• www.usatoday.com www.usatoday.com • www.web.xx.edu/~someone/news.htmlwww.web.xx.edu/~someone/news.html

Novices and Expert Chunking Novices and Expert Chunking DifferencesDifferences

Experts perceive visual stimuli differently Experts perceive visual stimuli differently than novices.than novices.

Expert chunksExpert chunks• chunks are large, rich in semantic information.chunks are large, rich in semantic information.• contain syntactic or surface details.contain syntactic or surface details.

Novice chunksNovice chunks• chunks are small and focused on syntactic chunks are small and focused on syntactic

featuresfeatures

Chunking and HCIChunking and HCI

CS majors are experts in programming, CS majors are experts in programming, computer science as are the designers computer science as are the designers of most UI’sof most UI’s

We expect that what CS experts “see” We expect that what CS experts “see” in a UI may differ from what a non-in a UI may differ from what a non-expert sees.expert sees.

Chunking and HCI DemoChunking and HCI Demo

DirectionsDirections• You will be shown two Pascal programs. You will be shown two Pascal programs. • You will see each program for 3 minutes. You will see each program for 3 minutes. • You are to study and memorize as much of You are to study and memorize as much of

the program as possible. the program as possible. • When the program is removed, you are to When the program is removed, you are to

write down as much of the program as you write down as much of the program as you remember.remember.

Chunking and HCI Demo (2)Chunking and HCI Demo (2)

show first programshow first program

Chunking and HCI Demo (3)Chunking and HCI Demo (3)

show second programshow second program

Chunking and HCI Demo (4)Chunking and HCI Demo (4)

How did you do? How did you do? Why did you do better on the "normal" Why did you do better on the "normal"

program?program? You as an expert perceive the normal You as an expert perceive the normal

program as chunks of program structure. program as chunks of program structure.

The scrambled program has no The scrambled program has no recognizable chunks.recognizable chunks.

Chunking and HCI Demo (5)Chunking and HCI Demo (5)

• • A non-programmer sees the two A non-programmer sees the two programs as both scrambled! programs as both scrambled!

Their recall performance is the same on Their recall performance is the same on both tasks.both tasks.

Chunking and HCI Demo (6)Chunking and HCI Demo (6)

When experts look at scrambled When experts look at scrambled program do not see patternsprogram do not see patterns• They see only randomly-arranged lines. They see only randomly-arranged lines.

They must remember "random lines" or They must remember "random lines" or "garbage. " "garbage. "

To novices To novices • scrambled and meaningful programs both scrambled and meaningful programs both

look random.look random.

Chunking and HCI Demo (7)Chunking and HCI Demo (7)

meaningful scrambled

recall

novices

experts

Typical findings for the deGroot task. Replicated in many domains including: chess, go, programming, basketball, volleyball, bridge....

Chunking and HCI Demo (8)Chunking and HCI Demo (8)

ConclusionConclusion• Expert designers cannot judge how a user Expert designers cannot judge how a user

of different expertise is going to experience of different expertise is going to experience an interface because the expert and non-an interface because the expert and non-expert see different things!expert see different things!

Chunking and HCI Demo (9)Chunking and HCI Demo (9)

Point regarding HCI:Point regarding HCI:• Experts and novices see, process, view exactly Experts and novices see, process, view exactly

the same stimuli (e.g.., screen) differently. the same stimuli (e.g.., screen) differently. • If you are an expert, it is impossible to If you are an expert, it is impossible to

interpret/use an interface in the same way as a interpret/use an interface in the same way as a novice. novice.

• Therefore Experts in programming can not rely Therefore Experts in programming can not rely on their intuitions about what makes a good on their intuitions about what makes a good interface when designing an interface for a non-interface when designing an interface for a non-expert.expert.