Introduction to Memory laura leventhal

Reference Chapter 14 Chapter 14

Types of Memory-Overview Sensory memory Sensory memory Short-term memory Short-term memory Working storage Working storage Long-term memory Long-term memory

Sensory Memory A sensory memory for each input channel A sensory memory for each input channel Echoic Memory Echoic Memory Iconic Memory Iconic Memory

Short-Term Memory Information from the outside world enters the cognitive system Information from the outside world enters the cognitive system Scratch-pad Scratch-pad Fast access, fast decay Fast access, fast decay Limited capacity Limited capacity

Working Storage A little more permanent that STM A little more permanent that STM Less permanent than LTM Less permanent than LTM Things like “where did I park my car” or a phone number remembered with rehersal. 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? 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. 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 Many things One ability experts have over novices is the ability to form and use longer and more complex CHUNKS. One ability experts have over novices is the ability to form and use longer and more complex CHUNKS.

Chunks Chunks guide visual perception. 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 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. How we group visual info is based on our experience.

Capacity of STM Measured in Chunks Measured in Chunks About chunksAbout chunks “The magic number 7”“The magic number 7”

Chunking Example We all can read English. Which of the following two telephone numbers is easier to remember? We all can read English. Which of the following two telephone numbers is easier to remember? EAT-FISH EAT-FISH Which URL? Which URL?

Novices and Expert Chunking Differences Experts perceive visual stimuli differently than novices. Experts perceive visual stimuli differently than novices. Expert chunks Expert 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 chunks Novice chunks chunks are small and focused on syntactic featureschunks 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 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 non- expert sees. We expect that what CS experts “see” in a UI may differ from what a non- expert sees.

Chunking and HCI Demo Directions Directions 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 the program as possible.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.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 show first program

Chunking and HCI Demo (3) show second program show second program

Chunking and HCI Demo (4) How did you do? How did you do? Why did you do better on the "normal" program? Why did you do better on the "normal" program? You as an expert perceive the normal program as chunks of program structure. You as an expert perceive the normal program as chunks of program structure. The scrambled program has no recognizable chunks. The scrambled program has no recognizable chunks.

Chunking and HCI Demo (5) A non-programmer sees the two programs as both scrambled! A non-programmer sees the two programs as both scrambled! Their recall performance is the same on both tasks. Their recall performance is the same on both tasks.

Chunking and HCI Demo (6) When experts look at scrambled program do not see patterns When experts look at scrambled program do not see patterns They see only randomly-arranged lines. They must remember "random lines" or "garbage. "They see only randomly-arranged lines. They must remember "random lines" or "garbage. " To novices To novices scrambled and meaningful programs both look random.scrambled and meaningful programs both look random.

Chunking and HCI Demo (7)

Chunking and HCI Demo (8) Conclusion Conclusion Expert designers cannot judge how a user of different expertise is going to experience an interface because the expert and non- expert see different things!Expert designers cannot judge how a user of different expertise is going to experience an interface because the expert and non- expert see different things!

Chunking and HCI Demo (9) Point regarding HCI: Point regarding HCI: Experts and novices see, process, view exactly the same stimuli (e.g.., screen) differently.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.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.Therefore Experts in programming can not rely on their intuitions about what makes a good interface when designing an interface for a non-expert.