Understanding Human Perception: A Deep Dive into Vision, Hearing, and Memory, Assignments of Computer Science

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chapter 1

the human

the human

• (^) Information i/o …
  • (^) visual, auditory, haptic, movement
• (^) Information stored in memory
  • (^) sensory, short-term, long-term
• (^) Information processed and applied
  • (^) reasoning, problem solving, skill, error
• (^) Emotion influences human capabilities
• (^) Each person is different

The Eye - physical reception

• (^) mechanism for receiving light and

transforming it into electrical energy

• (^) light reflects from objects
• (^) images are focused upside-down on

retina

• (^) retina contains rods for low light vision

and cones for colour vision

• (^) ganglion cells (brain!) detect pattern

and movement

Interpreting the signal

• (^) Size and depth
  • (^) visual angle indicates how much of view

object occupies

(relates to size and distance from eye)

• (^) visual acuity is ability to perceive detail (limited)
• (^) familiar objects perceived as constant size (in spite of changes in visual angle when far away)
• (^) cues like overlapping help perception of

size and depth

Interpreting the signal (cont)

• (^) The visual system compensates for:
  • (^) movement
  • (^) changes in luminance.
• (^) Context is used to resolve ambiguity
• (^) Optical illusions sometimes occur due

to over compensation

Optical Illusions

the Ponzo illusion the Muller Lyer illusion

Hearing

• (^) Provides information about environment: distances, directions, objects etc.
• (^) Physical apparatus:
  • (^) outer ear – protects inner and amplifies sound
  • (^) middle ear – transmits sound waves as vibrations to inner ear
  • (^) inner ear – chemical transmitters are released and cause impulses in auditory nerve
• Sound
  • (^) pitch – sound frequency
  • (^) loudness – amplitude
  • (^) timbre– type or quality

Hearing (cont)

• (^) Humans can hear frequencies from 20Hz to

15kHz

• (^) less accurate distinguishing high frequencies than low.
• (^) Auditory system filters sounds
• (^) can attend to sounds over background noise.
• (^) for example, the cocktail party phenomenon.

Movement

• (^) Time taken to respond to stimulus:

reaction time + movement time

• Movement time dependent on age, fitness etc.
• (^) Reaction time - dependent on stimulus type:
  • (^) visual ~ 200ms
  • (^) auditory ~ 150 ms
  • pain ~ 700ms
• (^) Increasing reaction time decreases accuracy

in the unskilled operator but not in the skilled

operator.

Movement (cont)

• (^) Fitts' Law describes the time taken to hit a

screen target:

Mt = a + b log 2 (D/S + 1)

where: a and b are empirically determined constants Mt is movement time D is Distance S is Size of target

 targets as large as possible

distances as small as possible

sensory memory

• (^) Buffers for stimuli received through senses - (^) iconic memory: visual stimuli - (^) echoic memory: aural stimuli - (^) haptic memory: tactile stimuli
• (^) Examples
  • (^) “sparkler” trail
  • (^) stereo sound
• (^) Continuously overwritten

Short-term memory (STM)

• (^) Scratch-pad for temporary recall
  • (^) rapid access ~ 70ms
  • (^) rapid decay ~ 200ms
  • (^) limited capacity - 7± 2 chunks

Long-term memory (LTM)

• (^) Repository for all our knowledge
  • (^) slow access ~ 1/10 second
  • (^) slow decay, if any
  • (^) huge or unlimited capacity
• (^) Two types
  • (^) episodic – serial memory of events
  • (^) semantic – structured memory of facts,concepts, skills semantic LTM derived from episodic LTM

Long-term memory (cont.)

• (^) Semantic memory structure
  • (^) provides access to information
  • (^) represents relationships between bits of information
  • (^) supports inference
• (^) Model: semantic network
  • (^) inheritance – child nodes inherit properties of parent nodes
  • (^) relationships between bits of information explicit
  • (^) supports inference through inheritance