MCAT Psych #2 Flashcards
sensation (transduction)
conversion of physical, electromagnetic, auditory, and other information from our internal and external environment to electrical signals in the NS.
o Goes from PNS to CNS, raw signal.
perception
the processing of information to make sense of its significance. Includes external sensory experience and internal activities of the brain and spinal cord. How to make sense of the world.
sensation vs. perception
sensation is the process of sensing our environment while perception is how we interpret these sensations,.
sensory receptors
neurons that respond to stimuli and trigger electrical signals.
distal stimuli
stimuli that originate outside of the body (ex: campfire)
proximal stimuli
directly interact with and affect the sensory receptors, and inform the observer about the presence of distal stimuli.
Ex: heat from campfire or photons from the light of the campfire.
psychophysics
the relationship between the physical nature of stimuli and the sensations and perceptions they evoke.
ganglia
collections of neuron cell bodies found outside the central nervous system.
o Transmit the data to the CNS
projection areas
location that the electrochemical energy signal is sent to in the brain which will then be further analyzed.
name the types of sensory receptors
o Photoreceptors: respond to electromagnetic waves in the visible spectrum (sight)
o Hair cells: respond to movement of fluid in the inner ear structures (hearing, rotational, and linear acceleration)
o Nociceptors: respond to painful or noxious stimuli (somatosensation)
o Thermoreceptors: respond to changes in temperature (thermosensation)
o Osmoreceptors: respond to the osmolarity of the blood (water homeostasis)
o Olfactory receptors: respond to volatile compounds (smell)
o Taste receptors: respond to dissolved compounds (taste)
photoreceptors
respond to electromagnetic waves in the visible spectrum (sight)
hair cells
respond to movement of fluid in the inner ear structures (hearing, rotational, and linear acceleration)
nocireceptors
respond to painful or noxious stimuli (somatosensation)
thermoreceptors
respond to changes in temperature (thermosensation)
osmoreceptors
respond to the osmolarity of the blood (water homeostasis)
olfactory receptors
Olfactory receptors: respond to volatile compounds (smell)
taste receptors
Taste receptors: respond to dissolved compounds (taste)
threshold
the minimum amount of a stimulus that renders a difference in perception.
o Ex: temperature changes throughout the day but it is not noticed until a big change (threshold is hit)
o Ex: temperature changes throughout the day but it is not noticed until a big change (threshold is hit)
absolute threshold
o the minimum of stimulus energy that is needed to activate a sensory system. The minimum intensity at which a stimulus will be transduced.
Threshold in sensation, not in perception.
How bright, loud, or intense a stimulus must be before it is sensed converted to an action potential.
Threshold of Conscious Perception
sensory systems send signals to the CNS without a person perceiving them (too small of stimulus or too brief)
A stimulus below the threshold of conscious perception arrives at the central nervous system but does not reach the higher-order brain regions that control attention and consciousness.
discrimination testing
what is the synonym of limina
threshold
what is the synonym for subliminal perception
threshold of conscious perception
discrimination testing
participant is shown one stimulus and then asked to identify if there is a difference in the second stimulus. Repeat until the participant reports noticing a change.
difference threshold
just noticeable difference (jnd)
the minimum difference in magnitude between two stimuli before one can perceive this difference.
Ex: sound frequency: the jnd is 3 hz, between sound waves at 440 Hz and 443 Hz.
Can also look at the jnd as a %, which would be 3/440 = 0.68%
• Weber’s law: there is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus.
o Thus, for higher magnitude stimuli, the actual difference must be larger to produce a jnd.
o Holds for all sensory modalities except for at the extremely high or low ends of each range.
Weber’s Law
there is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus.
o Thus, for higher magnitude stimuli, the actual difference must be larger to produce a jnd.
o Holds for all sensory modalities except for at the extremely high or low ends of each range.
signal detection theory
Perception of stimuli can be affected by nonsensory factors, such as experiences (memory), motives, and expectations. Focuses on the changes in our perception of the same stimuli depending on both internal (psychological) and external (environmental) context.
o Ex: hearing your name in a crowd: introvert or extrovert and size of the crowd matter
response bias
the tendency of subjects to systematically respond to a stimulus in a particular way due to nonsensory factors.
response bias is indicated by a significant proportion of misses or false alarms in a signal detection experiment
Describe a signal detection experiment
o During each trial, a stimulus (signal) may or may not be presented
Catch trials: trials in which stimulus is presented
Noise trials: trials in which stimulus is not presented
o After each trial, the participant must indicate whether or not a signal was given.
o 4 possible outcomes:
Hits: the subject correctly perceives the signal
False alarms: subject seems to perceive a signal but there is actually no signal
Miss: subject fails to perceive a given signal
Correct negative: the subject correctly identifies that there was no signal given
o Response bias in the subject is indicated by a significant portion of misses or false alarms.
Signal detection: catch trial
trials in which stimulus is presented
Signal detection: noise trial
trials in which stimulus is not presented
Signal detection: hits
the subject correctly perceives the signal
Signal detection: false alarms
subject seems to perceive a signal but there is actually no signal
Signal detection: miss
subject fails to perceive a given signal
Signal detection: correct negative
the subject correctly identifies that there was no signal given
_______ in the subject during a signal detection experiment is indicated by a significant portion of _____ or _______
response bias
misses or false alarms
adaptation
when our detection of a stimulus changes over time. We like to pay attention to the changing stimulus in our environment.
- Can have both a physiological (sensory) and psychological (perceptual) component
- Ex: pupils dilate or get smaller in dark and light physiological
- Ex: stop feeling the clothes on our body after we put them on psychological
what is the pathway for a stimulus to reach the brain
sensory receptor afferent neuron sensory ganglion spinal cord brain (projection areas)
which lobe is devoted to vision
occipital lobe
what form of stimulus do the eyes detect
photons
sclera
the white of the eye, thick structural layer that covers the exposed portion of the eye.
does not protect the cornea
provides structural support
what two blood vessels supply nutrients to the eye?
o Choroidal vessels: complex of intermingling blood vessels between the sclera and retina.
o Retinal vessels: spread more inside the eye
choroidal vessels
complex of intermingling blood vessels between the sclera and retina.
retinal vessels
spread more inside the eye
retina
the innermost layer of the eye, contains the actual photoreceptors that transduce light into electrical information the brain can process.
The back of the eye and is like a screen consisting of neural elements and blood vessels.
o Converts photons to electrical signals.
Duplexity or duplicity theory of vision
the retina contains two kinds of photoreceptors: those specialized for light-and-dark detection and those specialized for color detection.
cones: color
rods: light and dark
cones
color vision and fine details, best for bright light
• The cones are named for the wavelengths at which they have highest light absorption: short (S, blue), medium (M, green), and long (L, red)
rods
good for reduced illumination, sensation of light and dark, night vision, not involved in color and low sensitivity to detail
• Contain rhodopsin: pigment
• Way more rods than cones in the human body
what wavelengths do short, medium, and long cones aborb?
short: blue
medium: green
long: red
there are way more _____ than ______ in humans (eye photoreceptors)
way more rods than cones
cornea
not covered by the sclera. A clear, domelike window in the front of the eye which gathers and focuses the incoming light. it is the first place that light passes through.
draw the structures of the front of the eye
anterior chamber posterior chamber iris: dilator pupillae and constrictor pupillae choroid cornea retina ciliary body canal of Schlemm ciliary muscle suspensory ligaments lens fovea optic disc vitreous humor
anterior chamber
lies in front of the iris
posterior chamber
between the iris and lens
iris
colored part of the eye, composed of two muscles
Dilator pupillae: opens the pupil under sympathetic stimulation
2. Constrictor pupillae: constricts the pupil under parasympathetic stimulation.
Dilator pupillae: Iris
opens the pupil under sympathetic stimulation
Constrictor pupillae: Iris
constricts the pupil under parasympathetic stimulation
the iris and ciliary body are continuous with the _______
choroid
ciliary body
produces the aqueous humor, which bathes the front part of the eye
• The aqueous humor then drains into the canal of Schlemm
• Contraction of the ciliary muscle (part of the ciliary body) is under parasympathetic control.
• Accommodation: As the ciliary muscle contracts, it pulls on the suspensory ligaments and changes the shape of the lens.
the aqueous humor drains into the _____
canal of Schlemm
contraction of the ciliary muscle is under _______ control
parasympathetic
accomodation
As the ciliary muscle contracts, it pulls on the suspensory ligaments and changes the shape of the lens.
lens
lies right behind the iris and helps control the refraction of incoming light
vitreous
a transparent gel that supports the retina.
macula
central secretion of the retina, has a high concentration of cones
o Center-most point is the fovea which contains only cones.
Move further away from the fovea, more rods, less cones.
there is a blind spot where the _____ leaves the eye
optic nerve
what is the path from rods/cones to the optic nerve
o Rods/cones bipolar cells (amacrine and horizontal cells) ganglion cells
Bipolar cells: highlight gradients between adjacent rods or cones
Ganglion cells: group together to form the optic nerve
• A lot of rods and cones project to one ganglion cell, losing resolution
Projection happens from the back of the eye to the front of the eye.
Amacrine and horizontal cells: accentuate slight differences between the visual info in each bipolar cell. Important for edge detection and perception of contrasts.
• Intermediate and lateral processing of info
• Not really a steps but can mediate info.
bipolar cells
highlight gradients between adjacent rods or cones
ganglion cells
group together to form the optic nerve
• A lot of rods and cones project to one ganglion cell, losing resolution
projection happens from the ______ of the eye to the ___ of the eye
back to front
moving from the receptors to the ganglion cells.
amacrine and horizontal cells
accentuate slight differences between the visual info in each bipolar cell. Important for edge detection and perception of contrasts.
• Intermediate and lateral processing of info
• Not really a steps but can mediate info.
visual pathways
refer to both the physical and anatomical connections between the eyes and the brain and the flow of visual information along these connections.
describe the visual pathway
o 1. Left visual field to right retina and vice versa
o 2. Optic nerves
o 3. Optic chiasm: fibers from the nasal half (close to the nose) of each retina cross paths (Left visual field project to right side of the brain)
o 4. Optic tracts: pathway once it leaves the optic chiasm.
o 5. Lateral geniculate nucleus (LGN) of the thalamus
o 6. Visual cortex in the occipital lobe + superior colliculus