Human-Centered Design (Lec 2)

The Human (Lec 2)

• The human user is the primary focus when designing computer systems
• Understanding human capabilities and limitations (cognitive psychology) is crucial
• Designer insights into how humans perceive, process information, solve problems, and manipulate objects are important
• Designing systems that are easier and more intuitive to use.

Introduction Cont...

• The Model Human Processor (1983) simplifies human processing during computer interactions.
• It has three interacting subsystems: perceptual, motor, and cognitive
• Each subsystem handles information processing and has its processor and memory which vary depending on the task.
• The model outlines principles that govern human behavior in these conditions.
• The focus will be on the human's input-output channels, senses, and effectors, which will involve some low-level processing
• The course will then consider how human memory works, the process of complex problem-solving, skill acquisition, and error analysis in order to help in creating computer systems

Input-Output Channels

• Humans receive information using their senses and provide output using motor controls (effectors)
• There are five main sensory channels: sight, hearing, touch, taste, and smell.
• Vision, hearing, and touch are central in human-computer interactions (HCI)
• Visual input is most common, while auditory feedback and tactile feedback (from the mouse or keyboard) are also significant
• In human-computer interaction, information sent via our senses to the computer is considered input and output from the computer is considered output for the human

Input-output Channels Cont..

• Limbs, fingers, eyes, head, and vocal system are also involved in interaction with computer systems
• Information is primarily received visually from the screen using a mouse and keyboard
• Auditory feedback, like beeps, or voice messages, may also be involved
• Touch feedback is important, such as feeling a keystroke or mouse movement
• Hand-eye coordination is involved in inputting information through typing or mouse actions
• External sources of information can be translated/transferred to the computer via hearing or vision

Vision

• Human vision is a complex process with inherent physical and perceptual limitations
• Visual perception can be divided into two stages: physical reception of stimuli and processing of interpretation of these stimuli
• Understanding the eye as a physical receptor and the basic processes of vision is essential in computer design
• Understanding the eye's physical functioning (receiving, converting light into electrical energy, upside-down image reception) is important

Visual Perception

• Vision starts with light
• The eye receives and converts light into electrical signals
• Light is focused on the retina where rods and cones convert light to signals that the brain processes
• The visual system filters, processes, and interprets information to understand scenes, relative distances, shapes, colors.
• The ability to process size, brightness, and color is important for HCI design.

The capabilities and limitations of visual processing

• Visual processing involves converting light into images, and the brains interpretation of images is complex and influenced by expectations
• A presented image could have a different interpretation than the intended interpretation due to the complex process of converting and interpreting images

Hearing

• Hearing provides environmental information, such as distance, direction, and objects
• The ear consists of three sections: outer, inner, and middle ear
• The auditory nerve processes sound waves, producing signals the brain can interpret
• Vibrations in the air (sound waves) are transferred via the ear to the auditory nerves that send signals to the brain

Sound

• The human ear has a hearing range of 20Hz to 15kHz
• The auditory system filters incoming sounds, allowing attention to important information
• Sound is a less used channel in HCI, confined to warnings and notifications, though multimedia uses sound effectively
• Sound characteristics include frequency (pitch), amplitude (loudness), and wavelength

Characteristics of Sound

• Frequency is measured in Hertz (Hz) and relates to pitch, with higher frequencies relating to higher pitch
• Amplitude refers to the sound wave's height and reflects volume, with larger amplitudes correlating to greater volume
• Wavelength is the distance between sound wave crests and corresponds inversely to frequency. Higher frequency sounds have shorter wavelengths than lower ones.
• All three aspects affect how humans perceive sounds.

Touch

• Touch provides important information about the environment
• Touch sensory receptors (thermoreceptors, nociceptors, mechanoreceptors), located in the skin, are responsible for receiving and interpreting the signals
• Touch feedback is crucial in most HCI design, and is as important as visual or auditory feedback (especially in those with other impairments)
• Kinesthesis (limb and body position) is another key aspect along similar sensory lines relating to touch and movement.

Touch Cont...

• Kinesthesis (limb and body position awareness): The awareness of the position of body parts due to signals from receptors in the joints.
• Three types of receptors involved, including rapidly and slowly adapting, and positional receptors
• Awareness of limb position and movement is crucial for interaction with a computer system

Movement

• Movement time (reaction time + movement time) depends on physical abilities (age, fitness, experiences).
• Factors like practice and skill can improve movement time
• Speed and accuracy of movement are crucial for interactive designs relating to target selection e.g. clicking a button

Human Memory

• Human memory is crucial in computer interactions
• Understanding its structural aspects and limitations is key in designing user-friendly interfaces
• It includes sensory, short-term, and long-term memory

Types of Memory

• Sensory memory: Stores sensory stimuli briefly; visual (iconic), auditory (echoic), and tactile memory
• Short-term memory (Working memory): Stores and manipulates information relatively briefly, and has a limited capacity of approximately 7 ± 2 items
• Long-term memory (LTM): Stores large amounts of information long-term; divided into episodic (events) and semantic (facts/skills)

Sensory Memory

• Sensory memories act as temporary buffers for sensory inputs
• They play a role in processing continuous visual and auditory streams like animations and speech
• Duration is about 0.5 seconds

Short-Term (Working) Memory

• Short-term memory temporarily holds and processes information
• It has a limited capacity of about 7 ± 2 items
• Duration is 20-30 seconds
• Chunking/grouping and rehearsal help to extend the short-term memory duration

Long-Term Memory

• Stores and retrieves information long-term; potentially indefinitely
• Has unlimited capacity
• Access time is significantly slower than short-term memory
• Divided into episodic and semantic sections

Long-term memory Cont...

• There are memory structures that allow for accessing information, representing relationships, and carrying out inferences on different types of knowledge
• These structures include semantic networks, frames, scripts, and production rules

Semantic Network

• Represents relationships between pieces of information.
• Items are in classes, and inherit attributes from parent classes
• Useful for simple objects and activities

Frames

• Structured representations that organize information in slots (e.g. Fixed, Default, or Variable slots)
• Allow for the storage of attribute values for complex information
• Useful for expressing hierarchical structures

Script

• Models of stereotypical situations/sequences of events: Entry conditions, roles, props, scenes, tracks, all detailed
• Used for interpreting partial information.

Script (Example)

• Example of a script, including entry conditions, roles, props, scenes and tracks for a visit to the vet.

Production Rule

• Represents procedural knowledge (how to do something)
• Condition-action rules are stored in long-term memory
• When a condition matches, the corresponding action is executed
• Examples of production rules were given regarding dog behavior

Long-term memory processes

• Memory storage, forgetting, and retrieval are the main activities related to long-term memory
• Forgetting is explained by decay theory (memory fading naturally) and interference theory ( new information disrupts recall)
• Information from short-term memory moves to long-term memory through repeated exposure or rehearsal
• Meaningful information is better stored and retained

Long-term memory processes Cont...

• Forgetting in long-term memory takes place via decay theory (fading) or interference theory (new info disrupts old info)
• Retrieval of info is facilitated by retrieval cues (stimuli that trigger recall).
• Examples given (e.g. recognition, recall, retrieval cues (categories, vivid imagery))

Thinking, Reasoning, and Problem Solving

• Thinking can vary in its knowledge requirements
• Reasoning and problem-solving are categorized and have multiple types (deductive, inductive, abductive reasoning).

Deductive Reasoning

• Deductive reasoning derives logically necessary conclusions from given premises.
• The conclusion from the facts is not guaranteed to be true.
• An example given for deductive reasoning (implications involving assumptions that need not be true)

Inductive Reasoning

• Inductive reasoning generalizes from specific cases to draw inferences about general cases.
• The reliability of inferences from specific cases to broader generalities
• Example and illustration given about inductive reasoning.
• Wason's card example illustrates one example of this

Abductive Reasoning

• Abduction reasons from a fact to a possible cause/explanation of that fact
• Leads to possible, but not certain, conclusions
• Example given about possible reasoning and the potential inaccuracies in this

Problem Solving

• Problem-solving involves using existing knowledge to address unfamiliar situations
• Different theoretical perspectives on problem solving (Gestalt, Problem Space, Analogical Reasoning) were discussed
• Categories of errors, including slips (doing something right but the wrong way) and mistakes were mentioned (errors relating to intended actions not always coming to fruition)

Emotion

• Emotional responses influence performance positivity fosters creative and problem-solving while negativeness leads to narrow thinking
• Various theories of emotional responses are described (James-Lange, Cannon-Bard, Schacter-Singer theories)
• The biological response to stimuli termed affect, and how it affects people is discussed as well. (positive vs. negative affect)

Individual Differences

• While humans share common cognitive and perceptual processes, individual differences must be designed for in computer interactions
• Long term differences may relate to sex, capabilities, intellectual and mental abilities
• Short term differences relate to conditions impacting performance (stress, fatigue)
• Temporal changes relate to aging impacting user performance and accessibility

Psychology and the design of interactive systems

• Psychology knowledge is crucial in developing effective and user-friendly computer systems
• Knowledge about receiving, processing, and storing information and solving problems using different kinds of skills.
• Simple examples regarding selection and commands to avoid complex tasks were provided as suggestions in HCI
• Importance of understanding broader psychological context and specific experimental conditions in applying psychological principles is highlighted

This quiz explores the importance of understanding human capabilities and limitations in designing intuitive computer systems. It delves into the Model Human Processor and how cognitive psychology informs user interactions. Key concepts include perceptual, motor, and cognitive subsystems and the principles governing human behavior during computer interactions.