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chp 3: sensation - Coggle Diagram
chp 3: sensation
the hearing sense
perceiving pitch
pitch: psychological experience of sound that corresponds to the frequency of the sound waves; higher frequencies are perceived as higher pitches
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volley principle: states that frequencies from about 400 Hz to 4000 Hz cause the hair cells (auditory neurons) to fire in a volley pattern, or take turns in firing
place theory: states that different pitches are experienced by the stimulation of hair cells in different locations on the organ of Corti
sound waves and the ear
is a physical stimulus because sound can be measured in hertz (Hz): cycles (waves) per second + wavelengths + result of vibrations of air molecules
structure of the ear
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inner ear
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auditory nerve: bundle of axons of all the receptor nerves, from the hair cells in the inner ear
outer ear
pinna: visible, external part of the ear, serves as a kind of concentrator, funneling the sound waves from outside into the structure of the ear + entrance to auditory canal
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sensation: occurs when special receptors in the sense organs are activated, allowing various forms of outside stimuli to become neural signals in the brain
thresholds -> to change
just noticeable difference/difference threshold (JND): smallest difference between two stimuli that is detectable 50% of the time
absolute threshold: lowest level of stimulation that a person can consciously detect 50% of the time the stimulation is present
webner's law: whatever the difference between stimuli might be, it is always a constant
subliminal perception: behaviour influenced by stimuli that are just strong enough to activate sensory receptors but not strong enough for people to be consciously aware of them, act on the unconscious mind
signal detection theory-> used to assess accuracy of judgements, or decisions we make under uncertain conditions
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transduction: process of converting outside stimuli, such as light into neural activity
synesthesia: joined sensation, signals from various sensory organs are processed differently, resulting in the sense information being interpreted as more than one sensation
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the science of seeing
visual pathway
light from the right visual field falls on the left side of each eye's retina and vice versa, and then travels in a straight line through the cornea and lens -> image projected on the retina is actually upside down and reversed from left ot right
after light falls on retina -> stimulate a neural message that will travel along the optic nerve to the thalamus -> then to the visual cortex in the occipital lope of the left hemisphere
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retina -> optic nerve -> optic chiasm -> optic tract -> LGN of thalamus -> optic radiations -> primary visual cortex
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axons from temporal halves of each retina project to visual cortex on the same side of the brain; axons from nasal halves project to visual cortex on opposite side of the brain; optic chiasm is a point of crossover
perception of colour
opponent-process theory: theory of colour vision that proposes visual neurons are stimulated by light of one colour and inhibited by light of another colour
creates afterimages: images that occur when a visual sensation persists for a brief time even after the original stimulus is removed
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trichromatic theory: theory of colour vision that proposes 3 types of cones: red, blue and green
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light and the eye
structure of the eye
pupil: opening in the center of the iris that changes size depending on the amount of light in the environment
cornea: curved, transparent dome that bends incoming light waves so the image can be focused on the retina
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retina: innermost layer, incoming light is converted into nerve impulses, contains photoreceptor cells
blind spot: optic disc, where the optic nerve leaves the eye, there are no photoreceptor cells here
fovea: central area of retina where light rays are most sharply focused, greatest density of cones
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chemical senses:
gustation
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called a chemical sense because food molecules dissolve in saliva, which then fits into receptor sites
olfaction
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called a chemical sense because substance molecules are suspended in the air, carried to the nasal cavity, and fit into receptor sites
unique in that signals do not first travel to the thalamus before going to the brain, goes straight to olfactory bulbs, then to higher cortical areas such as the primary olfactory cortex
olfactory bulbs: two bulb-like projections of the brain located just above the sinus cavity and just below the frontal lobes that receive information from the olfactory receptor cells
other senses
somesthetic senses: the body senses consisting of the skin senses, the kinesthetic sense, the vestibular senses
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