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

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.