Sensory Processing/Perception Flashcards
What allows us to perceive depth?
Binocular cues: Retinal Disparity and Convergence
What allows us to perceive form?
Monocular cues: Relative size, Interposition, Relative height, Shading and contour
What allows us to perceive motion?
Monocular cues: Motion paralax (relative motion)
What allows us to perceive constancy?
Size constancy
Shape constancy
Color constancy
Perceptual organization
Describes how we see and experience different perceptual phenomena in the world around us
Depth
Form
Motion
Constancy
Describe the process of sensory adaptation regarding hearing
Inner ear muscle contracts when there’s a loud noise, which dampens the noise and protects ear drum from being damaged. This takes a few seconds to kick in –> doesn’t work for immediate loud noises, i.e. gunshot
Describe the process of sensory adaptation regarding touch
Sensory receptors become saturated and stop firing as much –> desensitization
Describe the process of sensory adaptation regarding smell
Sensory receptors in nose become desensitized to particular odors
Describe the process of sensory adaptation with proprioception
Mechanism not stated in video, but if someone puts on goggles that distort image of world, ie flips images upside down, over time the brain adapts and flips the image rightside up
Describe the process of sensory adaptation regarding sight. How does this differ from sensory adaptation in other modalities?
While most other modalities get some kind of down regulation, with sight you can get up or down regulation.
Lots of light: Pupils constrict, rods/cones become desensitized –> down regulation in ability to sense light
Dark: Pupils dilate, rods/cones synthesize more light sensitive molecules –> upregulation in sensitivity
What is Weber’s Law and what kind of relationship does it predict between the JND (incremental threshold) and the background intensity?
dI/I = k
Linear relationship
T/F: The absolute threshold of stimulation is a fixed, unchanging number
False
Can be influenced by: expectations, experiences, motivation, altertness
What are the different types of somatosensation? What determines the intensity for each modality?
- Thermoception (temperature)
- Mechanoception (pressure)
- Nociception (pain)
- Propioception (position)
For each modality, intensity correlates to neuronal firing rate (low intensity = low rate of firing, high intensity = high rate of firing)
How do somatosensory neurons encode information about timing?
Neuron firing may or may not adapt to the stimulus, which provides information regarding stimulus timing.
Non-adapting: The entire time a stimulus is being applied, there is no change in firing rate; each spike is spaced evenly
Slow-adapting: Neurons start off with high firing rate, then slows down over time; slow to adapt to change in stimulus
Fast-adapting: Neurons fires really quickly as soon as stimulus starts, then it will stop firing, then it will start firing again as soon as the stimulus stops
What structures located in the inner ear are particularly important parts of the vestibular system?
Semicircular canals: Anterior, lateral, and posterior
Otolith organs: utricle and saccule
What is the fluid located in the semicircular canals? How does it contribute to our vestibular sense?
Endolymph
When we rotate along a certain plane → causes endolymph to shift within that particular canal → allows us to sense what plane our head is rotating along
We are also sensitive to how much of fluid is moving and how quickly → we can also get information about the strength of rotation
How do the otolith organs contribute to our vestibular system?
They help us detect linear acceleration and head position
Within these structures are calcium carbonate crystals that are attached to hair cells within a viscous gel substance
If we accelerate in a direction or, for example, move from standing up to lying down, this causes the crystals to move because they are heavier than the surrounding gel environment
When they move, they physically pull on the hair cells they’re attached to → triggers an action potential that carries this information to the brain
Describe the physiological process in the semicircular canals that causes dizziness/vertigo
As we spin, the endolymph moves along the direction we’re turning, but this liquid doesn’t always stop spinning when we do (especially true if spinning vigorously or for a long period of time)
Continued movement of endolymph → signals sent to brain indicating you’re still moving even after you have stopped → causes dizziness
When fluid finally stops, dizziness subsides
→ Rotating in the opposite direction of how you were originally spinning encourages the movement of the endolymph in that opposite direction → can help stop the original motion of the endolymph by “canceling it out”
Describe the physiological process in the otolith organs that causes dizziness/vertigo
If you were in a situation without gravity (ie Astronaut), your otolithic organs probably wouldn’t work very well because gravity won’t pull down on them in the same way → concepts of up/down kind of become meaningless → can be really disorienting
Also a danger of scuba diving, because buoyancy can have the same effect as gravity → sometimes results in divers becoming disoriented in water
Especially true when they don’t have visual cues about which way is up and which way is down
Signal Detection Theory
Looks at how we make decisions under conditions of uncertainty.
Tries to figure out, at what point is a signal strong enough that we are able to notice it in the first place; at what point are we able to detect a signal?
Describe the 4 possible outcomes of signal detection theory
Signal Present, Response “Yes” = Hit
Signal Present, Response “No” = Miss
Signal Absent, Reponse “Yes” = False Alarm
Signal Absent, Response “No” = Correct Rejection
How does the strength of the signal (d’) affect the relative amount of hits/misses/false alarms/correct rejections?
If the signal is really strong, you might always get it right (either hit or correct rejection)
Hit>miss
If signal is weak, might get some false alarms and/or misses
Hit
*Note: d’ represents the difference between the means of the noise distribution and signal distribution
What is the difference between top-down and bottom-up processing?
Bottom-up Processing: Stimulus influences our perception; No preconceived cognitive constructs about what it is you’re looking at; Data driven; perception of what you’re looking at directs your cognitive awareness of that object
Top-down Processing: Uses your background knowledge/information/expectation to influence perception; Theory driven; our perception/behavior is influenced by our expectation
If you were looking at a ‘where’s waldo?’ image, what kind of processing (top-down or bottom-up) would you be using?
Top-down
This allows us to be goal-driven and we’re able to look through the picture and find Waldo.
In contrast, if we were using bottom-up processing, we would just be seeing a bunch of little people and we wouldn’t really be goal driven/trying to do anything
What are the laws outlined by the Gestalt Principles?
Similarity: Items that are similar to one another are grouped together by your brain
Pragnanz: Reality os often organized/reduced to the simplest form possible
Proximity: Objects that are close to one another are grouped together
Continuity: Lines are seen as following the smoothest path
Closure: Objects grouped together are seen as a whole
Label the parts of the eye:
Conjunctiva
Helps protect/moisturize the eyeball; protection from dust
If inflamed → pink eye
Cornea
Transparent, thick, fibrous tissue
Anterior ⅙ of the eyeball
Helps bend light; starts to focus the light
Protects front of eyeball
Anterior Chamber
From back of cornea to front of lens
Filled with aqueous humor
Helps provide internal pressure to maintain the shape of the eyeball
Allows nutrients/minerals to flow through this space to supply the cells of the cornea, iris, etc.
Aqueous Humor
Fluid that fills the anterior chamber
Helps provide internal pressure to maintain the shape of the eyeball
Allows nutrients/minerals to flow through this space to supply the cells of the cornea, iris, etc.
All light that hits the temporal side of each eye (does/does not) cross the optic chiasm, while all light that hits the nasal side (does/does not) cross the optic chiasm.
This allows information from the _____ visual field to go to the _____ side of the brain, and vice versa.
Does not; does
Right; Left (or left; right)
*Note: light that hits the temporal part of the eyeball does not come from the temporal visual field, but rather comes from the nasal visual field
Label the parts of the ear
Describe the auditory pathway in the brain starting from the auditory nerve
First, auditory information goes from the auditory nerve to the cochlear nuclei in the medulla. Axons of the cochlear nuclei synapse with neurons in the inferior colliculus (on the way to the inferior colliculus, some crossing occurs such that auditory information from each ear is sent to the opposite hemisphere).
From there, electrical signals are passed on to the medial geniculate nucleus of the thalamus, which sends information to the auditory cortex in the temporal lobe.
