biology and behavior ch 9-10

what is the difference between sensation and perception?

sensation

• the sense organs’ detection of external physical stimulus

• transmission of information about this stimulus to the brain

perception

• the processing, organization, and interpretation of sensory signals in the brain

• result in an internal neural representation of the physical stimulus

how doo humans localize sound?

sound is funneled into outer ear

• sounds located based on loudness and delay to ear

  • ex. if sound is coming from the left it will be louder and will be heard first by the left ear

  • since ears are located on sides of head sound shadow is created when sounds come from the sides but not the front or back

• sound is also processed in both brain hemispheres for each ear

  • but since the opposite side of the brain does most of the processing more sound information from the left ear will be processed in the right brain hemisphere and vice versa

where is the auditory cortex located?

superior temporal gyrus

what is the Fourier analysis?

ability to distinguish between people’s voices, sound broken into component frequencies

what is prosody?

convey meaning in speech for intonation, emphasis, and rhythm

how do hearing aids work?

cochlear implants

place theory

• perception of sound dependent on location of component frequency vibrations along basilar membrane

what is frequency?

peceptual experience: pitch

• high frequench = high pitch

  • ex. high notes from a piccolo

• low frequency = low pitch

  • low notes played by a tuba

• frequency theory

  • whatever the pitch of a sound wave, nerve impulses of a corresponding frequency will be sent to the auditory nerve

  • only accounts for low-end frequencies

what areas are responsible for language in the brain?

language: generation and understanding of written, spoken and gestural communication

• acquired through learning

• prosody

  • convey meaning in speech for intonation, emphasis and rhythm

• brain areas responsible for language

  • broca’s

  • wernicke’s

• impairments

  • aphasia

  • dyslexia

• impairment in reading

what is broca’s aphasia?

nonaffluent - pauses

trouble with finding words

articulation issues - instead of “write” says “rike”

agrammatic - trouble with adverbs, adjectives, conjunctions

• no ifs, and, or buts

issues with reading and writing

what is wernicke’s aphasia?

trouble with understanding and producing language

fluent speech - no meaning (word salad)

does not realize there is a problem

what function does each part of the hair cell perform?

cochlea houses auditory receptors in organ of corti in inner ear

• responsible for transduction into neural energy

connect to auditory nerve cells

contain cilia - embedded in tectorial membrane

two types: inner and outer

• outer sharpen and amplify sound

• inner are primary sensory receptors that project to the auditory nerve

how do humans communicate without spoken language?

nonverbal communication - sign language

• humans developed sign language to compensate for loss of hearing

  • human infants exposed to sign language babble with hand signs

• monkeys and apes can be trained in human sign language

what do we learn from patients suffering from brain damage?

how language is localized into structures

• broca’s area

• wernicke’s area

what is ventral and dorsal stream?

auditort cortex separates into two streams

dorsal stream

• parietal lobe to frontal lobe

• “where” the sound is

ventral stream

• more temporal lobe

• “what” the sound is

what are the parts of the ear?

outer ear

pinna

• outer skin flap

  • protection, localization, amplification

auditory canal

• protection, temperature control, resonance

tympanic membrane (eardrum)

• seals off auditory canal

• first area for sound waves to strike, vibrates in response to sound waves, transmits vibrations to middle ear

middle ear

separates inner and outer ears,

amplifies sound, act as lever to increase force, focus vibrations of large surface onto small surface

• malleus (hammer)

  • vibrates on response to tympanic membrane

• incus (anvil)

• stapes (stirrup)

  • transmits vibration to oval window

air (outer ear and middle ear) - low impendance

fluid (inner ear) - high impendance

inner ear

cochlea

• filled with fluid, moves when stapes pushes against oval window

how many receptors are in the human eye?

97 million photoreceptors

• highly active cells compared to other cells in the body

what is the visible spectrum of light?

electromagnetic spectrum

• includes a variety of energy forms

• light is described by its wavelength

  • visible light ranges from 380 nm to 800nm

what is retinal disparity?

depth perception

visual motion perception

• focus on retinal (binocular) disparity cues

  • difference in object location due to difference in perception between left and right eye

• use extra-retinal signals from eye movements to gage depth

what affects our percepetion of color?

color is the observer’s visual experience, not an object characteristic

results from the color that bounces off an object to the eye

• different experience for everyone

• can train color perception acuity

• color constancy

  • ability to perceive color as the same in different lighting

disorders associated with vision often come from X chromosome

• disproportionally affect men

what are the theories of color vision?

trichromatic theory - Young and Helmholtz (1800s)

• receptors for three colors: red, green, blue

  • color mixing of 3 colors creates all possible color combinations

• no explanation for yellow

opponent process theory - Edward Hering (1878)

• color perception depends on the receptors that make antagonistic responses to 3 pairs of colors

  • red on, green off

  • yellow on, blue off

  • black on, white off

    • this not only takes care of yellow, but also explains the phenomenon of complementary afterimages

  • color blindness

how do the theories of color vision work together?

3 types of color receptors

• red, green and blue

connected in an opponent-process fashion in the ganglion cells

• combining colors from different forms of lodopsin

• instead of combining 2 receptors all receptors engaged at once

  • more like a circle than a line with all colors mixing

what is an agnosia?

agnosia

• caused by impairments in visual processing

object agnosia

• cannot identify objects

prosopagnosia

• can’t identify familiar faces

• often person has both prosopagnosia and object agnosia

what is synthesia?

excessive connection between areas (overbinding)

• causes combination of normally unrelated sensory experiences (seeing sounds and hearing colors)

what is blind sight?

loss of vision can result for a variety of reasons

• brain still processes information relayed from eyes even if a person can’t assess this information

how do we focus on objects?

accommodation

• refraction is necessary to focus light rays and this is done by the lens

  • eyes must change shape to of lens to focus on objects

what is the fovea?

central point on the retina where cones are tightly packed

• offers best color and detailed vision

what are the rods and cones?

rods

• pigment is rhodopsin

• low-light vision

• not useful in highly lit situations

cones

• pigment in iodopsin

  • different forms of iodopsin respond to different wavelengths of light for color vision

• high-intensity light levels needed

• mostly in fovea

what is the blind spot?

area on the retina where the optic nerve leaves the eye

• no photoreceptors located here so no visual processing can occur

what part of the visual system is responsible for optical illusions?

optical illusions can cause visual confusion

afterimages affected by cones

often occur in the retina

• the complex cell responds to lines and edges

  • can betricked into thinking the line continues if the changel is limited, cells in the retina not infallible

what are the parts of the eye?

cornea

• transparent outer coat that protects the eye

pupil

• muscle that changes size to regulate ligth intensity

iris

• center of eye that allows light through

aqueous humor

• fluid inside the eye

lens

• focuses light on the retina

vitreous humor

• opaque gel-like substance that maintains eye shape

retina

• light-sensitive tissue at the back of the eye where rods and cones are concentrated

fovea

• central focus on the retina where cones are located

optic nerve

• transmits visual information to the brain through action potentials

blind spot

• area where no photoreceptors are located

photoreceptors

• cells in the retina that initially transduce light energy into neural energy

rods

• 120 million, light sensitive (not color), found in periphery of retina, low activation threshold

cones

• 6 million, are color sensitive, found mostly in fovea