Transcript Introduction to Memory - Bowling Green State University

Introduction to Memory
laura leventhal
Reference

Chapter 14
Types of Memory-Overview
Sensory memory
 Short-term memory
 Working storage
 Long-term memory

Sensory Memory
A sensory memory for each input
channel
 Echoic Memory
 Iconic Memory

Short-Term Memory
Information from the outside world
enters the cognitive system
 Scratch-pad
 Fast access, fast decay
 Limited capacity

Working Storage
A little more permanent that STM
 Less permanent than LTM
 Things like “where did I park my car” or
a phone number remembered with
rehersal.

Using info about STM in
Interface Design
What can we do with this information?
 Even with the short overview, we can
get some clues about why so many
interfaces are failures for the majority of
their users.

What makes an expert?
Many things
 One ability experts have over novices is
the ability to form and use longer and
more complex CHUNKS.

Chunks
Chunks guide visual perception.
 When we see things in the visual field,
the way that we group is based on the
way that we chunk visual inputs
 How we group visual info is based on
our experience.

Capacity of STM

Measured in Chunks
• About 5 - 7 chunks
• “The magic number 7”
Chunking Example

We all can read English. Which of the
following two telephone numbers is
easier to remember?


1-827-549-4890
1-300-EAT-FISH

Which URL?
• www.usatoday.com
• www.web.xx.edu/~someone/news.html
Novices and Expert Chunking
Differences
Experts perceive visual stimuli
differently than novices.
 Expert chunks

• chunks are large, rich in semantic
information.
• contain syntactic or surface details.

Novice chunks
• chunks are small and focused on syntactic
features
Chunking and HCI
CS majors are experts in programming,
computer science as are the designers
of most UI’s
 We expect that what CS experts “see”
in a UI may differ from what a nonexpert sees.

Chunking and HCI Demo

Directions
• You will be shown two Pascal programs.
• You will see each program for 3 minutes.
• You are to study and memorize as much of
the program as possible.
• When the program is removed, you are to
write down as much of the program as you
remember.
Chunking and HCI Demo (2)

show first program
Chunking and HCI Demo (3)

show second program
Chunking and HCI Demo (4)
How did you do?
 Why did you do better on the "normal"
program?
 You as an expert perceive the normal
program as chunks of program
structure.
 The scrambled program has no
recognizable chunks.

Chunking and HCI Demo (5)
• A non-programmer sees the two
programs as both scrambled!
 Their recall performance is the same on
both tasks.

Chunking and HCI Demo (6)

When experts look at scrambled
program do not see patterns
• They see only randomly-arranged lines.
They must remember "random lines" or
"garbage. "

To novices
• scrambled and meaningful programs both
look random.
Chunking and HCI Demo (7)
experts
recall
novices
meaningful
scrambled
Typical findings for the deGroot task.
Replicated in many domains including:
chess, go, programming, basketball,
volleyball, bridge....
Chunking and HCI Demo (8)

Conclusion
• Expert designers cannot judge how a user
of different expertise is going to experience
an interface because the expert and nonexpert see different things!
Chunking and HCI Demo (9)

Point regarding HCI:
• Experts and novices see, process, view
exactly the same stimuli (e.g.., screen)
differently.
• If you are an expert, it is impossible to
interpret/use an interface in the same way
as a novice.
• Therefore Experts in programming can not
rely on their intuitions about what makes a
good interface when designing an interface
for a non-expert.