CIS465: Adv. Info. Sys. Memory Systems Min Song Information Systems Dept.
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Transcript of CIS465: Adv. Info. Sys. Memory Systems Min Song Information Systems Dept.
CIS465: Adv. Info. Sys.Memory Systems
Min Song
Information Systems Dept.
The Human Information Processing System
To support human systems, need to know something about its basic characteristics memory performance characteristics behavior of input and output channels internal architecture
The Human Information Processing System
As with computer, one basic activity is info processing.
HC Interface is for exchanging information So, focus on user as info processing system, and
study how the user handles info input and output.
Basic Information Processing Units
Memories
Computer
Human
Registers Short-Term Memory Main Memory Intermediate Memory Disks Long-Term Memory Tape, cards, optical disks Books, pictures,
External Memory Input Devices Keyboard, Mouse,
Touchscreen Touch
Voice Recognizer Ears Digital Scanner Eyes Output Devices
Screen, Printer Eyes Voice Synthesizer Voicebox The Glove Hands Processes Operating System Executive Control
Unit Compiler Pattern Recognition Applications Knowledge and
Skills
Human Constraints and Task Accomplishment
Limited available resources. High use, reduced processing Resource-limited Tasks Data-limited Tasks
Reduce Memory Load
Reduce demands on user's short-term memory Establish meaningful defaults Define intuitive short-cuts Visual layout of user interface should be based on a
familiar real world metaphor Disclose information in a progressive fashion
Competition for Critical Resources
Multiple tasks interfere and compete with each other. Two basic tasks in any form of user interaction:
Functional: user works with the content of the problem at hand (e.g., laying out a financial plan on a spreadsheet)
Operational: user works with the tools provided to do the task (e.g., moving the cursor around the spreadsheet or invoking spreadsheet commands).
Competition for Critical Resources
Functional and operational aspects compete for same scarce resources.
Skill in task performance can free up cognitive resources overlearning, “chunking”
Basic Processes of Human and Computer Systems Computers work in cycles:
read input data, convert to internal form (read-scan phase)
interpret the data (think phase), provide an output response to the input (response
phase). Humans process data in a similar cycle:
read and/or scan the input data presented to them (read-scan)
interpret this data by thinking about it (think phase) prepare appropriate response by sending signals to the
motor system (e.g., speech) (response).
Basic Processes of Human and Computer Systems
Three basic human systems handle input and output for the cycle: 1. the perceptual system (read-scan) 2. the cognitive system (think) 3. the motor system (respond)
The Perceptual System
The basic perceptual systems are: auditory visual touch
Each has a buffer, preprocessing and connection to cognitive system
The Cognitive System
holds new information short term memory (STM) [aka WM]
tries to match it to elements in long term memory (LTM)
If the information is completely new, relatively few matches are found user has to rehearse info in STM to keep it from
decaying might store it in LTM
The Cognitive System
Example of rehearsal: remembering a phone number
Short Term Memory
small capacity, fast read/write speeds, highly volatile Tasks which can cause forgetting in STM include
those with distractions (e.g., multiple attention grabbing items
happening at the same time). low discrimination between presented information “large” number of unique (unrelated) items
Long Term Memory
unlimited capacity, slow read/write speeds (about 5 seconds per item stored), fairly stable
forgetting=losing links, not nodes recall tends to be more general than specific declarative: facts procedural: rules, how to do things
The Motor System
comprised of many different muscle systems controlled primarily by the visual system Motor movements viewed by the visual system, which
sends its information on to the cognitive system, which then makes minor adjustments in the motor movements. These are sent as commands to the muscles to adjust the movement.