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sensation and perception (psyc 305) exam 1 study guide
what is sensation?
the physical intake of sensory information
what is perception?
the mental interpretation of sensory information
what is transduction?
when environmental energy turns into nerve impulses
what is top-down processing?
perception is influenced by our mental processes, used for more complex stimuli
what is bottom-up processing?
perception is influenced by what our senses pick up with little to no mental influence
what is an example of top-down processing?
If you see a blurry photo of a cat, but you can still tell it’s a cat because you know what a cat typically looks like
what is an example of bottom-up processing
You notice specific details like the shape of the ears, the tail, and the whiskers, and then piece these details together to recognize it as a cat.
what is an absolute threshold?
the minimum amount of stimulation needed to detect an event
what is a just noticeable difference?
the smallest amount of change in the intensity of sensory stimulus we can detect
what is a two point threshold?
minimum distance at which two stimuli can be distinguished
what is webers law?
the reaction between stimulus and sensation is a constant fraction
how does webers law relate to difference thresholds?
large stimuli = large JND, harder to tell difference between intense stimuli
small stimuli = small JND, easier to tell difference
what is the method of limits?
when the stimuli start low enough to be undetectable and gradually increase over time until they can be detected.
what is signal detection theory?
the idea that responses in a detection ask depend on sensory and decision processes
what is a hit in signal detection theory
report perceiving the stimulus and it was present
what is a false alarm in signal detection theory
you report perceiving the stimulus but it was absent
what is a correct rejection in signal detection theory?
you report the stimulus was absent and it was absent
what is a miss in signal detection theory?
you report the stimulus was absent but it was present
what is a neuron?
the basic building block of our nervous system, they are nerve cells that are specialized for communication
what is a synapse?
the gap between neurons, allows neurons to communciate
what is a myelin sheath?
insulates the neuron and speeds up neural signals
what is an action potential?
the signal getting passed to neurons, it will fire if it gets enough stimulation
what is an absolute refractory period?
brief period after firing that prevents another AP from occurring
how do action potentials occur?
neurons are filled with a liquid (that contains ions that have the electrical charge) and it goes through a process of distribution, sodium and potasiusm movement, etc.
what is depolarization?
when the mV goes from -70 to +40 due to the amount of positive ions
what is repolarization?
when the mV returns back to the normal -70
what are neurotransmitters?
chemical messenger released by neurons
what does it mean when a neurotransmitter is excitatory?
neuron depolarized and more likely to fire the AP
what does it mean when a neurotransmitter is inhibitory?
neuron is hyper polarized and less likely to fire the AP
what is the frontal lobes function? where is it located?
voluntary movement, higher functions, etc. located in the front
what is the parietal lobes function? where is it located?
sensory integration, coordination, self perception, etc. located in the top middle
what is the occipital lobes function? where is it located?
visual perception, located in the very back
what is the temporal lobes function? where is it located?
processing auditory info, langaage processing, memory, etc. and located below the frontal lobe
what is the function of the thalamus?
relays sensory signals and motor signals
what is brain lateralization?
process by which the brain is divided into two halves
what is the main function of each hemisphere
left: control the right side, rational thoughts/planning/details
right: controls the left side, emotional thought/creative writing/imaginations etc.
what is the split-brain phenomenon?
when the corpus callosum is severed, the two hemispheres cant communicate
right hemisphere: left visual field and spatial tasks
left hemisphere: right visual field and language
what is the difference between an fMRI and an MRI?
fMRI focuses on tracking oxygen levels in the blood and task-related changes in activity whereas the MRI focuses on showing what the brain looks like, not what it’s doing
what does our visual system process?
light waves
what is the cornea
focuses light and protects the eye
what is the pupil
where light enters into the eye
what is the iris
structure made up of muscle that control the pupil size
what is the lens
transparent structure thats controlled by the ciliary muscle (cm changes the shape of this)
what is the retina
light-sensitive membrane that receives light and turns it into a neural signal
what is the optic nerve
a bundle of nerve fibers that transmits visual information from the retina to the brain
what are aqueous and vitreous humors
aqueous: pocket filled with fluid that gives the eye shape
vitreous: transparent fluid that fills the vitreous chamber
what are the two photoreceptors? what do they process and where are they located?
Rods and Cones
Rods: specialized for night vision and black and white, key for peripheral vision (located by peripheral)
Cones: specialized for day vision, shades of color, key for seeing details (located by center of retina)
how do bipolar and ganglion cells contribute to visual processing?
bipolar: retinal cells that synapses with rods or cones but never both
ganglion: retinal cells that receive info from intermediate neurons and transmits info to the brain
how do ganglion cells utilize receptive fields?
to process information about light in the retina and send it to the brain
on-center (on-off): light falling on center increase neuron firing rates
off-center (off-on): light falling on center decrease neuron firing rate
what is myopia and why does it occur?
aka nearsightedness, lens bend too much light so its focused before the retina
what is hyperopia and why does it occur?
aka farsightedness, when light is focused behind the retina
why does astigmatism occur?
the cornea or lens is not curved correctly so light enters unevenly
what is a cataract?
lens becomes less transparent which allows less light in
what is glaucoma and why does it occur?
vision loss or blindness by damaging the optic nerve, its eye pressure buildup
what is presbyopia?
age related vision loss, inability to focus on nearby objects
what is the optic chiasm
part of the brain where the optic nerves from each eye cross, and is a key part of the visual pathway
what is the lateral geniculate nucleus?
a part of the thalamus that relays visual information from the retina to the primary visual cortex (V1)
what does ipsilateral mean?
same side of body
what does contralateral mean?
opposite side of body
what is the striate cortex (aka V1)
what you “see”, transmits information to two primary pathways called the ventral stream and the dorsal stream
what is blindsight?
perceptually blind because they can't see anything around them, can perceive “where” something is
what is the dorsal stream?
“Where and How”
V1 Sends some info here
Parietal Lobe processes spatial information
what is the ventral stream?
“What”
V1 sneds some info here
Temporal Lobe processes knowledge
what is hemispatial neglect?
a condition that causes a person to be unaware of stimuli on one side of their space.
what is visual object agnosia
a condition that makes it difficult to recognize objects that are seen, even though other visual functions are normal
what is prosopagnosia
facial blindness
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