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Chapter 5

Psychology 1000 Chapter Notes - Chapter 5: Visual Acuity, Olfaction, Cochlea

Course Code
PSYCH 1000
John Campbell

of 4
Psychology: Chapter 5 Notes (Exam)
Synesthesia: mixing of the senses
Sensation: is the stimulus-detection process by which our sense orangs respond to and
translate environmental stimuli into nerve impulses
Perception: making “sense” of what our senses tell us
Transduction: is the process whereby the characteristics of a stimulus are converted into
nerve impulses
Psychophysics: studies relations between the physical characteristics of stimuli and
sensory capabilities
Absolute threshold: the lowest intensity at which a stimulus can be detected correctly
50% of the time
(The lower the absolute threshold the greater the sensitivity)
Decision criterion: a standard of how certain they must be that a stimulus is present
before they will say they detected it
(Signal detection research shows us that perception is, in part, a decision)
Difference threshold: the smallest difference between two stimuli that people can
perceive 50% of the time
Weber’s Law: states that the difference threshold value for weights is a Weber fraction of
approximately 1/50
(if you hold a weight of 50 grams, the weight must increase to 51 grams for you to feel a
difference; if the weight is 500 grams it must increase to 510 grams for you to feel the
Sensory adaption: diminishing sensitivity to an unchanging stimulus
(that annoying clock in my room, after a while I stop hearing it because idgaf)
Lens: an elastic structure that becomes thinner to focus on distant objects and thicker to
focus on nearby objects
Retina: a multi-layered tissue at the rear of the fluid-filled eyeball
Myopia: Have good vision for nearby objects but have difficulty seeing faraway objects
Hyperopia: Excellent distance vision but have difficulty-seeing close-up
(there are about 120 million rods and 6 million cones in the human eye)
Rods: function best in dim light, are primarily black-and-white brightness receptors
Cones: which are color receptors, function best in bright illuminations
Fovea: a small area in the center of the retina that contains only cones
Bipolar cells: have synaptic connection with the rods and cones
(the bipolar cells, in turn, synapse with a layer of about one million ganglion cells, whose
axons are collected into a bundle to form the optic nerve)
Visual acuity: ability to see fine detail, (is greatest when the visual image projects directly
onto the fovea)
Photo-pigments: Impulses through the action of protein molecules
Dark adaption: is the progressive improvement in brightness sensitivity that occurs over
time under conditions of low illumination
Trichromatic theory: there are three types of color receptors in the retina (blue, green, and
red and cones are most sensitive to these three colors)
Opponent-process theory: proposed that each of the three cone types responds to two
different wavelengths
(one type responds to red or green, another to blue or yellow, and a third to black or
Dual-process theory: combines the trichromatic and opponent-process theories to account
for the color transduction process
Trichromats: people with normal color vision
Dichromat: is a person who is color-blind in only one of the systems (red-green or
Monochromat: is only sensitive to black-white system and is totally color-blind
Feature detectors: they fire selectively in response to stimuli that have specific
characteristics (when there are those circles that make up the image of a triangle)
Visual association cortex: here successively more complex features of visual scene are
combines and interpreted in light of our memories and knowledge
Sound: is pressure waves in air, water, or some other conducting medium
Frequency: is the number of sound waves, or cycles, per second
Hertz (Hz): is the technical measure of cycles per second
Amplitude: the vertical size of sound waves-that is, to the amount of compression and
expansion of the molecules in the conducting medium
Decibels (db): a measure of the physical pressures that occur at the eardrum
Eardrum: a movable membrane that vibrates in response to the sound wave
Middle ear: which houses three tiny bones
1. The hammer (malleus)
2. Anvil (incus)
3. Stirrup (stapes)
Cochlea: a coiled, snail-shaped tube about 3.5 centimeters in length that is filled with
fluid and contains the basilar membrane
Basilar membrane: a sheet of tissue that runs its length
Organ of Corti: contains about 16000 tiny hair cells that are actual sound receptors
(The higher the amplitude the higher the sound)
Frequency theory: nerve impulses sent to the brain match the frequency of the sound
Place theory: that the specific point in the cochlea where the fluid wave peaks and most
strongly bends the hair cells serves as a frequency coding cue
(at low frequencies, frequency theory holds true; at higher frequencies, place theory has a
better explanation)
Conduction deafness: caused by problems involving the mechanical system that transmits
sound waves to the cochlea
Nerve deafness: caused by damaged receptors within the inner ear or damage to the
auditory nerve itself, cannot be helped with a hearing aid
Gustation: (taste)
Olfaction: (smell)