Human-Computer Interaction Lecture 2

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Questions and Answers

What effect does increasing luminance have on visual acuity?

Increases visual acuity (correct)

Makes visual acuity variable

Decreases visual acuity

No effect on visual acuity

Which statement about flicker perception is accurate?

Flicker is less noticeable in peripheral vision.

Flicker becomes more noticeable as the display size increases. (correct)

Flicker is easiest to notice in central vision.

Flicker decreases with larger displays.

What does saturation refer to in color perception?

The spectral wavelength of light

The amount of whiteness in the color (correct)

The purity of the color

The brightness of the color

What is the optical center in graphic design?

A point slightly above the actual center Signup and view all the answers

How does reading speed compare between reading from a screen and reading from a book?

It is generally slower on a screen due to longer line lengths. Signup and view all the answers

What is the primary function of the outer ear?

It protects the inner ear and amplifies sound. Signup and view all the answers

Which of the following factors is NOT a component of sound?

Clarity Signup and view all the answers

What are the three subsystems of the Model of Human Processor?

Perceptual system, cognitive system, and motor system Signup and view all the answers

What deficiency can result from a lack of rods in the human eye?

Night blindness Signup and view all the answers

Which receptors in the skin detect heat and cold?

Thermoreceptors Signup and view all the answers

Which ear is responsible for identifying the location of a sound?

Both ears together Signup and view all the answers

Which type of vision do cones primarily provide?

Color perception Signup and view all the answers

In terms of visual perception, what does size constancy refer to?

The perception of size remains the same despite changes in distance Signup and view all the answers

What is the reaction time to an auditory signal?

150 ms Signup and view all the answers

What role do rapidly adapting mechanoreceptors serve?

Detect changes in pressure quickly. Signup and view all the answers

How do rods and cones differ in terms of their location in the retina?

Cones are located in the center, rods in the periphery Signup and view all the answers

What is the primary influence on user behavior that distinguishes human processors from computers?

External factors such as social environment Signup and view all the answers

How does the cocktail party effect relate to hearing?

It refers to our ability to focus on one conversation in a noisy environment. Signup and view all the answers

What type of sound can be associated with confirming an action in interface design?

Confirmation sounds Signup and view all the answers

What visual feature drives user attention according to peripheral vision design choices?

Flashing error messages Signup and view all the answers

What occurs in dim lighting as rods predominate vision?

Objects are more visible in peripheral vision Signup and view all the answers

Study Notes

Human Information Processing Model

The model includes three subsystems: perceptual system (handles sensory input), motor system (controls actions), and cognitive system (processes and connects the two).
Users analogized as information processing systems with aspects of input-output, memory, and processing.
External factors like social and organizational environments influence human information processing.

Human Senses

There are approximately 120 million rods and 6 million cones in the human retina.
Cones are concentrated in the fovea (3–4%) and are sensitive to blue light, facilitating vision in daylight.
Rods enable vision in dim light and are located peripherally in the retina; deficiencies lead to night blindness and color blindness.

Peripheral Vision

Users can enhance attention to critical messages (e.g., flashing error messages) at the screen's bottom.
Moving or distracting icons can affect visual focus, even if not directly looked at.

Visual Perception

Perception shapes understanding—"We don’t see things as they are, we see them as we are."
Size constancy and cues of familiarity or overlapping contribute to depth and size perception.
Increased luminance enhances visual acuity but can also increase flicker perception.

Color Perception

Components of color perception include hue (wavelength), intensity/brightness, and saturation (amount of whiteness).
Color vision is best when objects are viewed with the fovea due to a higher concentration of cones.

Reading and Patterns

Average adult reading speed is about 250 words per minute, recognizing words rather than scanning character by character.
Word shape recognition is critical for reading speed, and standard font sizes (9 to 12 points) offer optimal legibility.
Design considerations include the optical center of the page and minimizing familiarity distractions.

Human Ear and Sound

The human ear processes frequencies from 20 Hz to 15 kHz, providing the ability to locate sounds based on slight differences in reception between ears.
Sound components:
- Pitch (frequency)
- Loudness (amplitude)
- Timbre (quality of sound)

Interface Design Considerations

Attention, status information, confirmation sounds, and navigation are critical design aspects for effective user interaction.

Touch and Skin Receptors

Touch provides essential environmental feedback, despite being less important than vision and hearing.
Skin receptors include thermoreceptors (heat/cold), nociceptors (pain), and mechanoreceptors (pressure).

Reaction and Accuracy

Reaction times vary by stimulus: visual (200 ms), auditory (150 ms), and pain (700 ms).
Combining signals can lead to faster responses, while practice enhances reaction time.
Speed of reaction may impact accuracy; a balance must be maintained.

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Description

Dive into the second lecture of Human-Computer Interaction with Dr. Eng. Sadiq Ghalib. This session focuses on the Human Information Processing Model and the components of human modeling including perceptual, motor, and cognitive systems.