Chapter 3

Question 1

What is perception?

Answer 1

The prime means to acquire information about the state of the computer

The ability to collect and organise information about the environment using our physiological sensory
system

Builds on our expectation, attention and sensory information

Question 2

Why do we need to understand perception?

Answer 2

Design display technology

Explain why people use computers the way they do

Evaluate a user interface

Inform the design visualisations, interaction techniques, and user interfaces

Question 3

What are the perceptual tasks?

Answer 3

Discrimination:
The task of telling whether a difference occurs in sensory stimulation

Detection:
The task of telling whether an event of interest occurs (or not) in the environment

Recognition:
The task of categorizing stimulus as something

Estimation:
The task of estimating a property of an object of event in the environment

Search:
The task of localising an object of interest

Question 4

What does the discrimination threshold mean?

Answer 4

The minimum level of stimulation required for sensing

Question 5

Explain visual perception

Answer 5

Refers to perception through sensing of stimulation by light

Human visual system involves three neuroanatomically disting pathways

• What:
  The ventral pathway computes the identity of objects
• Where and How:
  The dorsal pathway encodes the location of visual objects and actions related
  to them
• Who:
  The superior temporal sulcus specialises in dynamic social processing

Visual system relies massively on parallel processing

Question 6

What is the foveal and peripheral vision?

Answer 6

Foveal vision:
- 1-2 degrees in the visual field where

• Seeing with high acuity and in color
• For perception of detailed information

Peripheral vision:

• Wide field-of-view, low resolution but sensitive
• For detection of stimuli

Question 7

Explain gestalt perception

Answer 7

Human vision is biased to perceive structure

We would rather perceive things as whole shapes, figures, and objects

Given a visual image, the brain chooses the simplest interpretation with the most symmetry

Question 8

Explain the importance of visual structure

Answer 8

Visual structure helps scan and understand information more quickly

Representations matter: They may be informationally equivalent, but involve different amount of
cognitive effort

Question 9

Explain visual salience

Answer 9

Saliency refers to the probability with which a graphical element can attract visual attention during the
first seconds of viewing a display.

Salience depends on the visual properties of the target and those of the rest of the display.