Chapter 4 Sensation/Perception Flashcards
How you feel sensations
- sensory organs get stimuli
- transduction
- impulses travel to thalamus (smell skips this step)
- thalamus sends it to diff cortices of the brain
Transduction
Sensory signals being transformed into neural impulses
Factors affecting sensation
- sensory adaptation
- sensory habituation
Sensation
Activation of any sense (vision, hearing, touch, taste, smell, vestibular, kinesthetic)
Perception
Process of understanding and interpreting sensations
Sensory adaptation
Decreasing responsiveness to stimuli due to constant stimulation
Sensory habituation
How our perception of sensations is partially due to how focused we are on them
Light
- electromagnetic waves in visible light spectrum
- Light intensity
- wavelength
Pathway light takes
- cornea
- pupil and lens surrounded by iris
- cones and rods of retina
- bipolar cells of retina
- optic nerve (axons of ganglion cells)
- lateral geniculate nucleus of thalamus
- visual cortices in occipital lobe
Cornea
Protective covering around eye, helps focus light
Pupil
Where light goes through to enter eye
Iris
Muscles that dilate and contract the pupil to let more or less light in (dilate in dark places, contract in light)
Lens
Curved and flexible structure used to focus the light entering the eye- called accommodation
Retina
- At the back of the eye
- made up of specialized neurons activated by different wavelengths of light (performs transduction)
Cones
- First layer of Retinal cells
- activated by color
- concentrated in center of eye, esp the fovea
- used when you focus on something, but not very useful in low illumination (that’s the reason you can’t see much color when it’s dark)
Fovea
Center of retina that has the highest concentration of cones
Rods
- Found in first layer of retinal cells
- cells that respond to black and white
- mostly found in the outer borders of the retina, used in peripheral vision and in low illumination
- outnumber cones 20 to 1
Bipolar cells
2nd layer of cells in the retina that activate when enough cones and rods are activated
Ganglion cells
3rd and final layer of retinal cells, activated when a certain amount of bipolar cells fire
- axons of ganglion cells make up the optic nerve
- nerve impulses sent to the brain through optic nerve
Blind spot
Hole in retina where optic nerve leaves the eye, has no rods or cones
Optic fiber
Made up of axons of ganglion cells, exits through optic disk to take neural impulses to brain
- impulses from left half of each retina goes to left brain hemisphere, right half of retina go to right half of hemisphere
Optic chiasm
Place where optic nerves cross each other, meet at the thalamus and then go to corresponding hemisphere
David hubel and Torsten Wiesel
Discovered that groups of neurons in brains primary visual cortex respond to specific elements of visual stimuli (feature detectors)
Feature detectors
Cells in the primary visual cortex that respond to only specific elements of visual stimuli
Color vision theories
- trichromatic
- opponent-process
- most researchers agree color vision is a combination of both
Trichromatic theory
- 3 types of cones in retina- detect either red, green, or blue
- activated in diff combination to make all the colors we see
- can’t explain afterimages and color blindness
After image
After staring at one color for a long time, and then looking at a blank space, you will see the same image in a complementary color
Complementary color
Colors that when mixed make grey
Colorblindness
Dichromats
- can’t see either red/green shades or blue/yellow shades
Monochromats
- can only see shades of grey
Opponent process theory
cones in retina control a pair of complementary colors, either:
- blue and yellow
- red and green
- black and white
- explains color blindness and afterimages
Sound
- waves created by vibrations in the air
- amplitude
- frequency
Light intensity
- how much energy light has, brightness
Wavelength (light)
distance bw waves of light
- what hue or color we see
- red is longest wavelength, violet is shortest wavelength (Roy g biv)
- reflected wavelengths of light are what we see while absorbed colors are hidden
- black is when all color wavelengths are absorbed, white when all color wavelengths reflected
Amplitude
- height of sound wave
- determines loudness (decibels)
Frequency (sound)
- length of waves
- determines pitch in megahertz
- low frequency waves are spaced far apart and have a low pitch
- 2 theories on how we hear pitch- place theory and frequency theory