Perception - Sensation and Perception Flashcards
What is perception?
Way in which we acquire knowledge of our surroundings (environmental objects or events) via our senses
Process of interpreting sensation signals for conscious awareness and for action in the brain
What is sensation?
Process of transformation physical stimuli to electrical signals which are sent to the brain
What is the perceptual process?
Distal stimulus -> proximal stimulus -> sensation -> perception
What we experience is the end result of the perceptual process
What is a distal stimulus?
Stimulus as it exists at its source
What is a proximal stimulus?
Stimulus as it enters our stimulus
How is the perceptual process evolutionary useful?
Aids survival and reproduction
Help seek positive/desirable things and avoid dangerous ones
What are the five main senses?
Visual
Auditory
Gustatory = taste
Olfactory = smell
Somatosensory = touch
What are three other senses of the body?
Proprioception = sense of body position and movement
Nociception = pain
Thermoception = temperature
What energies can caribou sense that we can’t?
Light into the UV spectrum to detect camouflaged predators
What energies can elephants sense that we can’t?
Sensitive to very low frequency sounds and vibrations to communicate over large distances
What energies can snakes sense that we can’t?
Detect infrared radiations to generate “thermal image” of prey
Why would senses evolve?
Because they provide reasonably accurate information about the world - however, not always as what we see is the end result of the perception process
What are illusions?
Situations in which perception differs from reality
What are some examples of visual illusions?
Perceiving objects at locations where no visual stimulus exists
Perception of objects is systematically distorted (misperceiving objects)
Ambiguous figures/sounds
Impossible objects
What are examples of illusions where objects are perceived at locations where no visual stimulus exists?
Lilac chaser
Hermann grid illusion
What are examples of illusions where objects are misperceived?
Muller Lyer
Ponzo
Zollner
Ebbinghaus (Titchner circles)
Cafe Wall
Shepard’s table
What are ambiguous figures?
Same image/stimulus gives rise to two or more distinct perceptions
Perception rarely ambiguous but tends to change over time
Produce different perceptions between different people that are stable over time
What are some examples of ambiguous figure illusions?
Bistable images
Necker cube
Rubin’s vase
Jastow’s duck/rabbit
What are ambiguous sounds?
Give rise to multiple bistable and stable perceptions
What are impossible objects?
Sensory input interpreted by brain as representing objects or scenarios that are physically impossible
What are examples of impossible objects?
Penrose triangle
Schuster’s conundrum (devil’s fork)
Endless stairs
Shepard scale
Rissett rhythm
Are objects perceived directly?
No - see end result of perceptual process
What are the two sources of information we have?
Current sensory input
Existing knowledge about environment
What is bottom-up processing?
Sensory input -> perception
Take information from sense and make judgements about nature of world solely based on that information
How is bottom-up processing driven?
Data
What is top-down processing?
Knowledge -> perception
Using knowledge about structure of world to influence perception
Searches for interpretations that are behaviourally relevant to us in that moment
How is top-down processing driven?
Conceptually
How are knowledge and perception related?
Perception frequently modified by knowledge but knowledge can’t always override perception
What are constructivist theories?
Emphasise importance of top-down processing
Many illusions better described as rational inferences rather than “perceptual errors”
Who are constructivist psychologists?
Hermann von Helmholtz
Gregory
What are direct theories?
Emphasise importance of bottom-up processing
Variety of clues in natural world that provide information
Perceiver not passive observer but interaction with environment
Who are direct psychologists?
James Gibson
When do illusions occur?
When input to our senses is degraded or lacking in structure
