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• Focus of Chapter 1 is on understanding the human element in human-computer interaction.
• Human properties like information processing, memory, and problem-solving skills need to be considered.
• Each person has their own capabilities and perception in all aspects of interaction

Information Input/Output

• Human information input and output occurs through vision, hearing, touch (haptic), and movement.

Information Storage in Memory

• Sensory, Short-Term, and Long-Term memory types are where information is stored

Information Processing & Application

• Humans apply reasoning, problem-solving skills, and learned skills, but are still prone to errors.

Emotion

• Emotion significantly influences human capabilities and performance.
• The design of interfaces should account for and leverage emotional responses.

Vision

• It involves physical reception of stimuli and processing/interpretation of said stimuli
• Physical reception involves mechanisms for receiving light and transforming it into electrical energy.
• Light reflects from objects, and images are focused upside-down on the retina.
• The retina contains rods for low light vision and cones for color vision.
• Ganglion cells then detect pattern and movement.
• Visual angle indicates how much of view object occupies
• Visual acuity refers to the ability to perceive detail.
• Familiar objects tends to be perceived as constant size.
• Cues like overlapping help perception of size and depth.
• Brightness is a subjective reaction to levels of light, affected by the luminance of objects, and measured by the smallest noticeable difference.
• Color is made up of hue, intensity, and saturation.
• Cones are sensitive to color wavelengths, with blue acuity being the lowest.
• Approximately 8% of males and 1% of females are color blind.
• The visual system compensates for movement and changes in luminance.
• Context aids in resolving ambiguity.
• Optical illusions occasionally occur due to overcompensation by the vision system.

Reading

• It involves visual pattern perception, decoding with internal language representation, and interpretation with syntax, semantics, and pragmatics.
• Reading involves saccades and fixations.
• Perception mainly occurs during fixations.
• Word shape plays an important role in recognition.
• Negative contrast can improve reading from computer screen

Hearing

• Provides information about distances, directions, and objects around the world from the environment.
• Sound goes from the outer, middle and inner parts of the ear.
• The outer ear protects the inner ear and amplifies sound.
• The middle ear transmits sound waves.
• Inner ear emits chemical transmitters which cause impulses in the auditory nerve.
• Sound is defined by pitch, loudness and timbre.
• Pitch is sound frequency, loudness is amplitude, and timbre is type or quality.
• Humans can perceive frequencies ranging from 20Hz to 15kHz, though distinguishing high frequencies is less accurate.
• Auditory system filters sounds, focusing on meaningful sounds over background noise; aka "cocktail party phenomenon."

Touch

• Offers crucial feedback about the environment.
• May be a critical sense for people with impaired vision.
• Stimuli is received through skin receptors like thermoreceptors (heat and cold), nociceptors (pain), and mechanoreceptors (pressure).
• Sensitivity varies across the body, e.g. fingers are highly sensitive.
• Kinesthesis is the awareness of body position, which affects comfort and performance.

Movement

• Time to respond to stimulus is reaction time plus movement time.
• Movement time is affected by age, fitness, etc.
• Reaction time depends on the stimulus type: visual (~200ms), auditory (~150 ms), pain (~700ms).
• Accuracy decreases as reaction time increases for unskilled operators, but not typically for skilled ones

Fitts' Law

• Describes time to hit screen target.
• The formula to workout Mt : Mt = a + b log2(D/S + 1)
• 'Mt' is movement time
• 'D' is Distance
• 'S' is Size of target
• Targets need to be as large as possible, and distances as small as possible.

Memory

• There are three types of memory function (Sensory, Short term, Long Term)

Sensory Memory

• Buffers for stimuli is received through senses.
• Iconic memory involves with visual stimuli.
• Echoic memory deals with aural stimuli.
• Haptic memory related to tactile stimulus.
• Sparkler trail, stereo sound are examples.
• The sensory memory is Continuously overwritten

Short-Term Memory (STM)

• Functions like a scratch-pad for temporary recall.
• With rapid access around 70ms from retrieval
• Has a rapid decay in around 200ms
• Has a limited capacity of around 7± 2 chunks.

Long-Term Memory (LTM)

• Functions like a repository for all our knowledge.
• It features a slow access speed, around 1/10 second.
• Decay is low, unlimited, if at all.
• Divided into Episodic memory which is the serial kind of events, and the Semantic structured memory for facts, concepts, and skills.
• Semantic LTM derived from episodic LTM.

Semantic Memory

• Semantic memory structure provides access to information and represents relationships between information bits to support inference.
• Using a model of semantic network, there is an inheritance, were child nodes inherit properties of parent nodes.
• Relationships between bits of information are made explicit.
• Inference is supported through this kind of inheritance.

LTM Models

• Frames is an information organized in a data structure.
• With data slots instantiated with values for instance
• Establishing Type-subtype relationships
• Scripts is a model that involves stereotypical information that is required to interpret a situation.
• Scripts have elements that can be instantiated with values for context.
• Production rules are the representation of procedural knowledge.
• Actions are determined when a matching condition is met.

LTM: Storage

• Information moves from STM to LTM by way of rehearsal
• Amount retained is proportional to rehearsal time, also known as the total time hypothesis.
• The process can be optimized by spreading learning over time, known as distribution of practice effect.
• Structure, meaning and familiarity makes information easier to remember.

LTM: Forgetting

• Decay is when Information lost gradually, but very slowly.
• Interference occurs when new information replaces prior information is lost due old information, and the prior one interferes when learning something new.
• Emotionally charged affects someone ability to store and retrieve memories efficiently

LTM: Retrieval

• Information reproduced from memory can be assisted by cues, e.g. categories, imagery with recall processes
• Recognition occurs when seeing familiar information .
• It is less complex than the process of recall - information is the cue.

Thinking

• Thinking encompasses reasoning (deduction, induction, abduction) and problem solving.

Reasoning

• It derived from deductive and inductive processes
• Deduction derives a logically necessary conclusion is derived from given premises.
• Induction generalizes from seen scenarios to unobserved ones.
• Induction is unreliable because it can only prove something false, not true.
• Abduction is a type of reasoning with events of the cause
• Is is also unreliable and can lead to false conclusions
• People bring world knowledge to bear, which interferes with world.

Problem Solving

• Problem solving encompasses unfamiliar tasks that use knowledge to find and use those solutions
• Gestalt theory frames problem solving as productive and reproductive.
• Productive problem solving draws on insight and problem restructuring.
• The approach led away info about behaviorism
• In Problem Space Theory, the problem space comprises multiple problem states.
• Problem solving involves generating those states using legal operators.
• Heuristics are used to choose operators, e.g. means-ends analysis.
• This problem solving system functions within human information processing limits such as STM and is applied in well-defined areas, e.g. puzzles.
• Problem Solving by Analogy maps from novel problems in new domains and utilizes information from similar problems in similar domains
• Analogy mapping is difficult with domains that are semantically different.
• Skill acquisition relates skilled behavior to chunking
• STM is optimized through chunking information
• Conceptual not superficial understanding of all problems
• Information structured more effectively

Errors

• Slips occur when the intention is correct, but the action is flawed
• Mistakes arise from wrong intention, can be caused by humans that build faulty mental models
• It wrong or different from the actual system then errors do happen as a result

Emotion

• James-Lange: emotion is our interpretation of a physiological response to a stimuli
• Cannon: emotion is a psychological response to a stimuli
• Schacter-Singer: emotion is the result of our evaluation of physiological responses in alignment with environment conditions
• Emotions involves both mental and physical ways to respond to the stimuli around
• The biological response to physical stimuli is called affect. Positive and negative affects respond with creative and narrow thinking in ways respond to various different emotions
• Negative feelings increases difficulty, Positive feelings increases ease
• Emotions has Implications for interface design, since Stress can increase the difficulty of problem solving
• Relaxed users forgive errors
• Aesthetics help increase reward system that affects users.

Individual Differences

• Long-term differences involve sex, physical abilities, etc.
• Short-term differences involve stress and fatigue.
• Differences regarding changing of age.
• Understand that designs should not exclude sections of the user population.

Psychology and Design

• Some direct applications are the usage of blue to express an aesthetic because poor acuity will allow relax users
• Right usages need the understanding of context from psychology and the experimental conditions to consider and respond through a particular fashion