Chapter 3 - Sensation and Perception Flashcards
What was the early philosophy of perception?
Concept of reality depends on what we learn about the world through our senses (eyes, ears, nose, tongue and skin).
Why have senses evolved?
Senses evolved to help increase our chances of survival.
What is sensation?
The ability to detect a stimulus and, perhaps, to turn that detection into a private experience.
What is perception?
The act of giving meaning to a detected sensation.
How does sensation become perception?
Receptor cells detect stimuli, convert into neural impulses and then transmit them to the brain – ‘transduction’. Brain organizes & interprets messages
What is the absolute threshold?
The point sensory info. can/cannot be detected 50% of the time
What is the Just Noticeable Difference?
Slightest + or - in physical stimulus required to produce Just Noticeable Difference (JND)
What is Weber’s law?
Psychological law quantifying the perception of change in a given stimulus. The law states that the change in a stimulus that will be just noticeable is a constant ratio of the original stimulus. Depends on percentage of change!
What is the signal detection theory?
Discriminating a stimulus from background noise & deciding whether the stimulus is actually present
What does signal detection involve?
Physical stimulus, Motivation to detect stimulus, previous experience, expectations, alertness
What is sensory adaptation and give an example?
Becoming accustomed to unchanging, constant stimuli (i.e. Smell of your home); firing rate slows
What is the visible spectrum?
400-700nm (between ultra violet and infared)
What does the cornea do?
Transparent covering that bends light rays into pupils
What is the pupil?
Small opening in center or Iris
What is the iris?
Coloured, circular muscle (reflexive), dilates/contracts to regulate entering light
What is the lense?
Disc that flattens to focus on distance and bulges for close images
What is Presbyopia?
Old eyes
What are the three layers of cells?
The first two send signals to the visual cortex but they do not respond directly to light.
Third layer (at the back of the retina) is where rods and cones are located
What are cones of the retina?
Color, fine-detail, work in bright light, focus on red, green, blue.
What are the rods of the retina?
Focus on black & white, work in dim light, helps adapt to dark places, bright places.
How do rods and cones transduce light?
Via the optic nerve to occipital lobe
Why do we have a blind spot?
No rods or cones in that area
What are the sensory receptors and location for vision?
Rods and cones in the retina
What are the three dimensions of colour that we experience?
Hue; colour
Saturation: purity
Brightness; intensity of the light energy we perceive
What is the trichromatic theory?
3 types of cones that respond best to different colours (blue, green or red).
What is the Opponent-process theory?
Three classes of cells respond by increasing or decreasing their rate of firing when different colours are present.
What is the Opponent-process theory?
Three classes of cells respond by increasing or decreasing their rate of firing when different colours are present. Red/green; yellow/blue; black/white
How are both theories of colour vision correct?
The trichromatic theory is consistent with what happens with the cones
The opponent-process theory is consistent with what happens with the ganglion cells.
If a tree falls in the woods does it make a sound?
No because there is no receptor
What is needed for sound ?
It require a medium - air, water or solid
What are the characteristics of sound?
Frequency, amplitude, timbre
What is the frequency of sound?
determined by the number of cycles completed by a sound wave in one second (Hz)
What is pitch?
how high (more vibrations) or low (fewer vibrations) the sound is - determined by frequency
What is the amplitude of sound?
Loudness (force which air molecules move) - Measured using ‘Bel’ (A.G.Bell) units – or decibels (dB).
What is the timbre?
Distinctness of sound with same pitch/amplitude. Flute almost pure sound; a tuning fork completely pure sound
What consists of the outer ear?
pinna, auditory canal (lined with hair), eardrum (tympanic membrane) - thin and flexible
What does the middle ear consist of?
Ossicles link eardrum to oval window - hammer (malleus), Anvil (Incus), Stirrup (stapes)
What is the smallest bone?
Stirrup (Stapes)