Model Human Processor: Cognitive System

Introduction

• Computer systems are designed to assist humans (users), therefore, the user's requirements come first.
• Understanding human capabilities and limitations is key to designing effective and intuitive interactive computer systems.
• Cognitive psychology provides insights into human perception, information processing, problem-solving, and object manipulation.

Model Human Processor

• The Model Human Processor was introduced in 1983 as a simplified view of human processing in computer interaction.
• It consists of three subsystems:
  • The perceptual system handles sensory input.
  • The motor system controls actions.
  • The cognitive system processes information to connect the other two.
• Each subsystem has processors and memory that vary in complexity depending on the task.
• The model outlines principles of operation that govern the behavior of these systems under different conditions.
• Focus will we given to input-output channels, the senses, responders/effectors, human memory, problem-solving, skill acquisition, reasons for mistakes, and how this can help design computer systems.

Input-Output Channels

• Humans interact with the world by receiving (input) and sending (output) information.
• In computer interactions, users receive output from the computer and provide input to it.
• The user's output becomes the computer's input, and vice versa.
• Human input occurs mainly through the senses, and output through motor control of effectors.
• The five major senses are sight, hearing, touch, taste, and smell, but vision, hearing, and touch are the most important to HCI.
• Taste and smell currently play a minor role in HCI.
• There are many effectors, including limbs, fingers, eyes, head, and the vocal system
• Fingers play a primary role in computer interaction through typing or mouse control.
• Personal computers provides visual, and auditory feedback (such as beeps).
• Touch is involved through the feel and sound of pressing keys or moving the mouse, providing feedback.
• Hands are used when inputting information to the computer such as typing or moving the mouse.
• Although sight and hearing do not directly send information to the computer, they help in receiving information from other sources that can be transmitted to the computer.

Vision

• Human vision is complex with physical and perceptual limitations, yet is the main information source for most people.
• Visual perception can be divided into:
  • Physical reception of stimuli
  • The processing and interpretation of those stimuli.
• The eye and visual system has limitations, but visual processing constructs images from incomplete information.
• Understanding reception and processing of stimuli is important for designing computer systems.
• Vision starts with light where the eye converts into electrical energy, and receptors change light into electrical signals sent to the brain.
• Images are focused upside-down on the retina.
  • The retina has rods for low-light vision.
  • The retina has cones for color vision.
• Visual perception requires information to be filtered and processed to recognize coherent scenes, determine relative distances, and differentiate colors.
• To create effective visual interfaces, it's essential to understand how we perceive size, depth, brightness, and color.
• Capabilities and limitations of visual processing transform and interpret images.
• Expectations affect the way images are perceived.

Hearing

• Hearing provides information about the environment regarding distances, directions, objects, etc.
• Sound, like hearing, begins with air vibrations or sound waves.
• The ear receives and transmits vibrations to the auditory nerves.
• The ear consists of three sections:
  • Outer ear: protects inner components and amplifies sound
  • Middle ear: transmits vibrations (sound waves) to the inner ear
  • Inner ear: releases chemical transmitters, causing impulses in auditory nerve
• The human ear hears frequencies from about 20 Hz to 15 kHz.
• The auditory system filters sounds, allowing us to ignore background noise and focus on important information.
• Sound can convey substantial information but is confined to warnings and notifications in interface design.
• Multimedia is an exception with music, voice commentary, and sound effects.

Characteristics of Sound

• Frequency:
  • Cycles of a sound wave occurring in one second, measured in Hertz (Hz).
  • Determines the pitch of the sound.
  • Higher frequencies equal higher pitches, and lower frequencies equal lower pitches.
• Amplitude:
  • The height of the sound wave, reflecting energy amount.
  • Determines loudness/volume of sound.
  • Larger amplitudes produce louder sounds, and smaller amplitudes produce softer sounds.
• Wavelength:
  • The distance between crests/troughs of a sound wave.
  • It's inversely related to frequency.
  • Higher frequency sounds have shorter wavelengths, while lower frequency sounds have longer wavelengths.

Touch

• Touch provides essential environment information.
• Touch is important feedback means, especially in computer systems such as pressing buttons.
• Important to know that haptic perception is secondary and vital for those with impairment.
• Touch isn't localized with stimuli received through the skin.
• Skin has three types of sensory receptor:
  • Thermoreceptors: respond to heat and cold
  • Nociceptors: respond to intense pressure, heat, and pain
  • Mechanoreceptors: respond to pressure
• Kinesthesis, another aspect of haptic perception, involves awareness to the body/limbs’ positions via joint receptors.
  • Rapidly adapting: responds to limb movement
  • Slowly adapting: responds to movement and static positions
  • Positional receptors: respond only to static positions

Movement

• The time taken to respond to a stimulus is reaction time + movement time.
• Movement time depends on physical characteristics like age and fitness of the subjects.
• Skill/practice can reduce reaction time.
• Speed and accuracy of movement are important in the design of interactive systems.
• Time taken to move to a specific target on screen, like buttons, menu items, or icons are parameters taken in to consideration.

Human Memory

• Human memory is a crucial role for user interaction to computer systems
• It influences information processing, retention and recall during interaction.
• Understanding memory structure and limitations is essential for user-friendly interfaces
• Types of Memory:
  • Sensory Memory
  • Short-Term (Working) Memory
  • Long-term memory

Sensory Memory

• Sensory memories buffer stimuli:
  • Iconic memory: visual stimuli
  • Echoic memory: aural stimuli
  • Haptic memory: touch
• Sensory memories are overwritten by new information
• Information transfers to short-term memory through attention, which filters for focus
• Attention concentrates on one of several competing stimuli/thoughts.
• Selective focus is important since sensory/mental processes have limited capacity.
• Duration: lasts under a second (0.5 seconds)
• HCI applications: perceiving animations/speech continuously.

Short-Term (Working) Memory

• Capacity: Holds a small amount of information for a short period.
• It allows for immediate processing and manipulation, acting as a 'scratchpad' for temporary recall.
• Capacity: Limited to about 7±2 items.
• Duration: Lasts for about 20-30 seconds.
• Characteristics:
  • Chunking: Grouping information into chunks to increase capacity.
  • Rehearsal: Repeating information to extend duration in short-term memory.
• Role in HCI:
  • Avoid overwhelming users.
  • Familiar icons.
  • Clear instructions.
  • Logical grouping.

Long-Term Memory

• Function: Stores information over extended periods, possibly indefinitely.
• Characteristics that differ from short-term memory are:
  • Huge/unlimited capacity
  • Slow access: taking ~ a tenth of a second
  • Slow forgetting, if forgetting occurs.
• There are types of long-term memory:
  • Episodic memory represents memory of events/experiences in serial form
  • Semantic memory is a collection of records, derived from episodic memory, of facts/skills acquired.

Long-Term Memory Structures

• Access to information and the representation of information relationships
• Semantic networks:
  • Supports interference
  • Items are associated with each other in classes
  • Items can inherit attributes from parent classes
  • Doesn't allow modeling of more complex objects that are composed of items/activities
• Frames
  • Structured representation that organize information into data structures and allow attribute values to be added
  • Frame slots can contain default, fixed or variable information

Frames cont'd

• Each frame is instantiated once slots are filled with values
• Frames can be linked together in networks to represent hierarchical knowledge.
• Frames extend semantic nets by including structured, hierarchical information.
• They represent knowledge items in a way that makes the relative importance of each information expressed.
• Slots have types:
  • Fixed: values have to be set
  • Default: have usual attribute value that can be overridden in instances
  • Variable: allow values to be filled in within a specific instance
• Additionally, slots can contain procedural knowledge so that actions and operations are associated with a slot to be performed when slot's value changes.
• Scripts:
  • Attempt to represent stereotypical knowledge about situations.
  • A script represents default/stereotypical information, allowing understanding of partial descriptions.
  • A script has elements that like slots can be filled with appropriate information.

Script elements

• Entry conditions: conditions to be satisfied for a script to activate
• Result conditions: the state of true after the script terminates
• Props: objects involved in events within the script
• Roles: the actions performed by participants.
• Scenes: sequences of events that happen
• Tracks: a variation of the general pattern

Production Rule

• Procedural involves knowledge representation that tells how to do something.
• Condition-action rules are stored long-term.
• Information can come into short-term memory to match a condition which results in execution of action.

Long-Term Memory Processes

• The core activities in memory are storage of information, forgetting information, and retrieving information.
• Information can move to long-term memory through repetition.
• Information also needed to be related/meaningful.
• Meaningful and familiar information allows integration in to long-term memory because of semantic structure.
• Two main theories explain long-term forgetting information
• Decay Theory:
• Experiment supported by Ebbinghaus.
• Memory fades logarithmically as is lost rapidly and then slowly over some time
• Jost's Law: memory traces that are equally strong, the older one is more durable.
• Interference Theory:
• Retroactive Inhibition: Loss of old information for new one.
• Proactive Inhibition: Old memories interfere with with new information

Memory and Information Retrieval

• Forgetting might be just a retrieval problem.
• Evidence indicates that information is generally never entirely lost.
• Proactive inhibition shows older information can be recovered
• Tip of tongue phenomenon suggests information is present but not easily accessible
• Cues can assist with recall and recognition

Thinking

• Thinking can be simple or complex.
• Two categories of thinking:
• Reasoning
• Problem-solving
• Reasoning is use to draw conclusions and infer knowledge.
• Reasoning is deductive, inductive, or abductive.

Reasoning

• Deductive:
  • Derives logically necessary conclusion
  • Conclusion isn't necessarily true.
• Inductive:
  • Generalizing seen cases/experience to infer unseen cases.
  • Information is unreliable when proving true.
• Abductive:
  • Reasons from fact to a causing action/state.
  • Used to derive explanations.
  • Unreliable.

Problem Solving Perspectives

• Problem Solving can be done utilizing the following reasoning:
  • Reasoning
  • Problem Theory
  • Gestalt View Emphasis
  • Problem Space Theory Concepts
  • Analogical Reasoning Method

Error

• Errors of two type:

1. Slip a. Right intention but unable to perform, skill based errors
2. Mistakes a. Wrong intention that is rule based.

• These models create understanding of behavior if behavior is different errors can occur

Emotion

• Emotional responses include performance, creativity, and problem solving.
• Negative emotions lead to narrow thinking
• Problems can be difficult when frustrated/afraid if they relaxed.
• Theories of how emotion work:
  • James-Lange: the interpretation physiological response to stimuli
  • Cannon: psychological response to stimulu
  • Schacter-Singer: the results of evaluated physiological response The biological response of physical stimuli is called affect.

Emotion and Reasoning

• Affect influences how we respond with situations with:
  • Creative problem solving
  • Narrow thinking
• Affect can make it harder/easier to do a task.

Individual Differences

• Shared Processing: Humans share similar cognitive and perceptual processes with.
• Key factors to consider when differentiating characteristics of:
  • Long term: sex, intellectual, physical abilities
  • Short term stress and fatigue
  • Temporal aging and accessibility
• Designs accommodate differences

Psychology and Design

• Using the knowledge humans apply when receiving, processing, and recalling information help solve and acquire computer skills.
• However, application requires context.
• A lot of knowledge has been distilled in:
  • Guidelines
  • Cognitive Models
  • Experimental and analytic evaluation.