Presentation notes

Sensation and Perception:

• Sensation - detecting stimuli from enviornment

• Perception - brain interpretation of sensory infor making sense of sensation

• Visual perception: retina captures light signals and changes them into neural signals that your brain uses to make and process images through visual cortex

• Structure of the eye:

  • cornea and lens - focus light onto the retina

  • retina - contains photoreceptors

  • optic nerve - sends signals to the brain

  • rods - detect light/darkness

  • cones - detect color

• Depth perception

  • depth perception can be affected by age and drugs

  • it is how we see in 3d

• Activity - sensation is raw input and sensation is brain trying to figure wout what it is

Vision:

Eye Anatomy:

Iris - regulates amount of light allowed into eye

Pupil - where light enters the eyes

Lens - behind the iris and focuses on an image

Retina - contains photoreceptors rods and cone respond to light

Bipolar cells - transports neural impulses from the rods and cones to the gaglion cells

Ganglion cells - axons of these cells make up the optic nerve

Optic nerve - sends sensory info from sight to brain

Rods - sensitive to intensity of light (gray)

Cones - transmits sensation of color

Fovea - dense with cones where vision is most prominent

Blind spot - where ganglion axons meet to create the optic nerve

Visual acuity - the sharpness of the vision

Cornea - forms outer surface of the eyeball and is transparent - bends light

Dark adaptation - when you adjust to the different amount of light - adjusting

• Light

  • Visible light - part of the electromagnetic spectrum that stimulates the eye and produces visual sensations

  • the hue of a color is determined by the wave length

  • the brightness of the color is determined by the amplitude of the wave

• Color vision

  • warm colors - reddish yellowish colors

  • cool colors - blue-green colors

  • Complementary colors - descriptive of colors of the spectrum when combined produce white or nearly white light

• Light vs. pigments - mixing complementary lights produce white light while mixing pigment makes gray or black color

• Afterimage - staring at a color for a long time creates and after image in its complementary color

• Theories of Color Vision

  • Trichromatic theory : suggests 3 types of cones red green adn blue that combine to produce color vision

  • Opponent-process theory: states that colors are perceived through opposing pairs

  • Modern understanding: combines both theories - cones detect colors, but signals are processed in an opponent manner

• Color Blindness

  • Trichromats: people with normal color vision

  • Dichromats: Partially color blind have difficulty seeing red-green or blue-yellow

  • Monochromats: completely color blind who only see shades of black white and gray

  • Ishihara color palates are used to test color blindness

Hearing:

• Hertz: unit that is frequency of sound waves

• Decibels - unit expressing loudness

• Cochlea- inner ear, bony tubed that contains

• organ of Corti - receptor for hearting that lies on the basilar membrane in the cochlea

• Auditory nerve - the axon bundle that transmits neural impulses from the organ of Corti to the brain

• Sound is the vibration of molecules in a medium such as air or water

  • Pitch - determined by frequency #’s of cycles per second in Hz

  • loudnes- height or amplitude of sound waved expressed in dB

• The Ear

  • Outer ear - shaped to funnel sound to ear drum

  • middle ear - eardrum and 3 small bones the bones amplify pressure

  • inner ear - transforms vibrations into electrical impulses

  Anatomy

• Cochlea - snail shell shape converts sound waves into electrical impulses - divide into 3 chambers

• Basilar membrane - thin but stiff converts sound waves to neural signals

• Organ of Corti - contains 16,000 hair cells that dance in response to vibrations and generate impulses to the brain by the auditory nerve

• Locating sounds

  • sound location is found by whether the sound is heard more in right or left ear

  • loudness and sequence in which the sound reaches the ears can help locate sounds

• Perception, loudness, and pitch

  • sound is heard by vibration transmitted to the brain

  • loudness and pitch related to # of receptor organs of corti fire and how often

  • more sensory neurons fired the louder the sound

• Place theory - pitch of a sound is determined by the section of the basilar membrane vibrates depending on the sound made

• Frequency theory - have to match the frequency of sound waves with neural impulses

• Volley Principle - groups of neurons that take turns firing signals to respond to sound

• Deafness - one in 10 Americans have a hearing impairment

• conductive deafness - damage to the middle of ear - hearing aids

• sensorineural deafness - damage to the inner ear, loss of hair cells or auditory nerve - cochlear implants