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sensation
bringing information from the outside world into the brain
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perception
selecting organizing and interpreting sensory information
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1. Sensory organs receive energy from or are otherwise stimulated by the environment
2. sensory receptors convert this energy into neural signals which are sent to the brain
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Absolute threshold of sensation
smallest detectable level of stimulus
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Just noticeable difference (JND)
smallest detectable change in intensity of stimulus
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Weber's Law
- Just noticeable difference varies as a proportion of the intensity
- for ex. vision has to be intensified much less than taste for you to perceive difference
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transduction
- converting a stimulus into neuronal signals
- sensory receptors produce neural impulses when they receive chemical/physical stimulation
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coding
the way information is encoded in neural signals
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frequency theory
frequency is encoded by the rate of neuronal firing
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place theory
different neurons in the inner ear code for different frequencies
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Is frequency theory or place theory correct?
- Both are used for all frequencies
- Place coding is relied on more for high frequencies, frequency coding for low frequencies
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rods
- achromatic
- greater sensitivity in low light
- found more in retina periphery (better light sensitivity)
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cones
- chromatic
- not as sensitive to light
- found more in the center of retina
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What are the three different types of photopigments for cones?
- S (blue light)
- M (green light)
- L (red light)
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trichromatic theory
Color vision results from activity in 3 different types of cones that are sensitive to different wavelengths (S, M, L)
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What is unexplained by the trichromatic theory?
Why color leave afterimages
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opponent-process theory
- Visual system treats colors as complementary pairs
- all colors are combinations of yellow OR blue PLUS red or green
- accounts for idea of opposite colors
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when is unique blue perceived?
when S receptor is stimulated and M and L are not
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when is unique yellow perceived?
when M and L are stimulated and S is not
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when is unique red perceived?
When L & S are stimulated and M is not
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x topic cortical organization
primary sensory cortices represent sensory info in a structured manner
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retintopic organization
adjacent points in space are processed by adjacent points in visual cortex
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tonotopy
similar tones are processed near each other
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cortical magnification
more cortical space is devoted to more sensitive regions of body (somatosensory cortex)
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process of transduction
sensory receptors ->connecting neurons -> thalamus -> cortex
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signal detection theory
detecting a stimulus requires making a judgment about its presence based on subjective interpretation of ambiguous information
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response bias
a participant tends to report detecting a signal when trial is ambiguous
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sensory adaptation
decrease in sensitivity to constant level of stimulation
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5 basic qualities of taste
sweet sour salty bitter umami (savory)
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supertasters
especially intense taste sensation
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odorants
chemical particles involved in smell
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olfactory epithelium
thin layer of tissue embedded w. small receptors
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olfactory bulb
brain center for smell
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what is the process of odorants to brain?
odorants-> naval cavity -> olfactory epithelium -> olfactory bulb -> other brain areas
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pheromones
chemicals released by animals which trigger behavioral reactions in other animals
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touch
- conveys sensations of temperature, pressure and pain
- delivers sense of where our limbs are in space
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where are pressure receptors located?
at bases of hair follicles and capsules in skin
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what are the two types of pain and why are they different?
- fast fibers: sharp immediate pain (myelinated axons)
- slow fibers: chronic, dull, steady pain (non-myleniated fibers)
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process of sound waves reaching brain
outer ear-> auditory canal ->eardrum -> ossicles -> oval window -> movement of basilar membrane -> hair cells bend -> info is sent to auditory nerve
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cornea
eye's thick transparent outer layer, focuses incoming light
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lens
light is bent farther inward and focused to form image on retina
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retina
contains photoreceptors that transduce light into neural signals
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accomodation
change in shape of lens to focus on distant/near objects
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how is info processed from the left visual field?
info reaches retina (via ganglion axons) -> optic nerve ->optic chiasm -> thalamus -> R. visual cortex
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3 categorizations of color
- hue
- saturation (color's purity, vividness of hue)
- brightness (determined by amount of light which reaches eye)
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subtractive color mixing
- color is determined by mixture of wavelengths from a stimulus
- occurs within stimulus
- is a physical process
- ex. mixing paints
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subtractive primary colors
red, yellow, blue
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additive color mixing
interaction of wavelengths within the eye's receptors
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vestibular sense
perceptions of balance
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gate control theory
- to experience pain, pain receptors must be activated, neural "gate" in spinal cord must allow signals through to brain
- cognitive factors such as distraction and positive moods can close the gate
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parallel processing streams in vison
- ventral stream: perception and recognition of objects (what)
- dorsal stream: spatial perception (where)
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blindsight
when someone experience some blindness but subconsciously retains some sight
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what is the purpose of cochlear implants?
to restore hearing for people with loss of hair cells
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kinesthetic sensory system
assists in perception body's position in space and in voluntary movement
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