1st QUIZ

• Two stages in vision

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  • physical reception of stimulus

  • processing and interpretation of stimulus
• The retina contains rods for low light vision and cones for colour vision
• ganglion cells (brain!) detect pattern and movement
• Size and depth - visual angle indicates how much of view object occupies
• Brightness

  –subjective reaction to levels of light

  –affected by luminance of object

  –measured by just noticeable difference

  –visual acuity increases with luminance as does flicker
• Colour/Color

  –made up of hue, intensity, saturation

  –cones sensitive to colour wavelengths

  –blue acuity is lowest

  –8% males and 1% females colour blind
• Context is used to resolve ambiguity
• Optical illusions sometimes occur due to over compensation
• Reading

  •Several stages:

  –visual pattern perceived

  –decoded using internal representation of language

  –interpreted using knowledge of syntax, semantics, pragmatics

  •Reading involves saccades and fixations

  •Perception occurs during fixations

  •Word shape is important to recognition

  •Negative contrast improves reading from computer screen
• Hearing

  •Provides information about environment:  distances, directions, objects etc.
• 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
• pitch  –  sound frequency
• loudness   –  amplitude
• timbre  –  type or quality
• •Humans can hear frequencies from 20Hz to 15kHz
• Touch(haptic perception)

  •Provides important feedback about environment.

  •May be key sense for someone who is visually impaired.
• thermoreceptors for heat and cold
• nociceptors  for pain
• mechanoreceptors  for pressure
• Kinethesis  - awareness of body position–affects comfort and performance.
• Movement

  •Time taken to respond to stimulus:  reaction time + movement time

  •Movement time dependent on age, fitness etc.
• •Fitts' Law describes the time taken to hit a screen target:•

    Mt = a + b log2(D/S + 1)
• iconic memory for visual stimuli
• echoic memory for aural stimuli
• haptic memory for tactile stimuli
• Short-term memory (STM) - Scratch-pad for temporary recall
• Long-term memory (LTM) - Repository for all our knowledge
• episodic  – serial memory of events
• semantic  – structured memory of facts,concepts, skills
• Models of LTM - Frames

  •Information organized in data structures

  •Slots in structure instantiated with values for instance of data

  •Type–subtype relationships
• Models of LTM - Production rules

  Representation of procedural knowledge.

  Condition/action rules

  if condition is matched

  then use rule to determine action.
• decay – information is lost gradually but very slowly
• Interference - new information replaces old
• retroactive interference - old may interfere with new: proactive inhibition
• recall – information reproduced from memory can be assisted by cues, e.g. categories, imagery
• recognition – information gives knowledge that it has been seen before–less complex than recall - information is a cue
• Deductive Reasoning/Deduction – derive logically necessary conclusions from given premises.
• Inductive Reasoning/Induction - generalize from cases seen to cases unseen