Sensory Perception Flashcards
Binocular Cues
This gives them retinal disparity. Eyes are ~2.5 inches apart which allows humans to get slightly different views of objects of world around. Gives humans an idea on depth.
Convergence
- Gives humans an idea of depth as well based on how much eyeballs are turned.
- Gives humans a sense of depth.
- Things far away – muscles of eyes relaxed.
- Things close to us – muscles of eyes contract.
Monocular Cues
- These give humans a sense of form of an object.
- Can infer with one eye.
- The closer an object it is perceived as being bigger.
Interposition (overlap)
- Perception that one object is in front of another.
- An object that is in the front is closer.
Relative Height
Things higher are perceived to be farther away than those that are lower.
Shading and Contour
- Using light and shadows to perceive form depth/contours
- Example: crater/mountain.
Motion Parallax
“relative motion” Things farther away move slower, closer moves faster.
Size Constancy
One that appears larger because its closer, we still think it is the same size.
Shape Constancy
- A changing shape still maintains the same shape perception.
- Example: a wall frame that is hanging off the wall still looks like a rectangle.
Color Constancy
Despite changes in lighting which change the image color falling on our retina, we understand (perceive) that the object is the same color.
Sensory Adaptation
Our senses are adaptable and they can change their sensitivity to stimuli.
Hearing Adaptation
- Inner ear muscle: higher noise = muscle contract
- Takes a few seconds to kick in! So does not work for immediate noises like a gun shot.
- Example: rock concert for an entire afternoon
Touch
Temperature receptors desensitized over time.
Smell
Desensitized receptors in your nose to molecule sensory information over time.
Proprioception
Is the sense of the position of the body in space. Example: “sense of balance/where you are in space.”
Sight
Down regulation or up regulation to light intensity.
Down Regulation
- Light adaptation.
- When it is bright out, pupils constrict and the desensitization of rods and cones.
Up Regulation
- Dark regulation.
- Pupils dilate-, rods and cones start synthesizing light sensitive molecules
Weber’s Law
- 2 vs. 2.05 lb weight feel the same.
- 2 vs. 2.2 lb weight difference would be noticeable.
- ΔI (JND)/I (initial intensity) = k (constant)
- Example: 0.2/2 = 0.5/5 = 0.1, change must be 0.1 of initial intensity to be noticeable
Just Noticeable Difference (JND)
The threshold at which you’re able to notice a change in any sensation.
Absolute Threshold of Sensation
The minimum intensity of stimulus needed to detect a particular stimulus 50% of the time. Some will detect it , others won’t.
Difference Threshold
That’s the smallest difference that can be detected 50% of the time.
Factors of the Absolute Threshold
- Expectations – ex. Are you expecting a text.
- Experience (how familiar you are with it) – ex. Are you familiar of the phones text vibration sound.
- Motivation – ex. Are you interested in the response of the text
- Alertness – Are you awake our drowsy. Ex. You will notice text if you are awake
Somatosensation (Types)
- Temperature (thermoception)
- Pressure (mechanoception)
- Pain (nociception)
- Position (proprioception)
Intensity of Somatosensation
How quickly neurons fire for us to notice. Slow = low intensity Fast = high intensity.
Neuron Timing (Types)
- Non-adapting- neuron consistency fires at a constant rate.
- Slow-adapting - neuron fires in beginning of stimulus and calms down after a while.
- Fast-adapting - neuron fires as soon as stimulus start…then stops firing. Starts again when stim stops).
Vestibular System (Inner Ear)
Focus on inner ear - in particular the semicircular canals (posterior, lateral, and anterior; each orthogonal to each other)
Endolymph
When we rotate the fluid shifts in the semicircular canals – allows us to detect what direction our head is moving in, and because we can detect how quickly the endolymph is moving we can determine the strength of rotation.
Otolithic Organs
- Help us to detect linear acceleration and head positioning.
- Example: In these are CaCO3 (Calcium carbonate) crystals attached to hair cells in viscous gel. If we go from lying down to standing up, they move, and pull on hair cells, which triggers AP. These would not work very well w/o gravity! Buoyancy can have effects as well, particularly without visual cues on which way is up/down.
Signal Detection Theory
Looks at how we make decision under conditions of uncertainty – discerning between important stimuli and unimportant “noise”.
Role of Signal Detection Theory in Psychology
- Imagine being given a list.
- Then a second list.
- Now experimenter asks, which words on the second list were on the first.
- Person has to have uncertainty as they are not sure whether a certain word is exact or similar than the one in the first list.
Hit, False Alarm, Correct Rejection & Miss
- Hit: the subject responded affirmative when a signal was present.
- False Alarm: the subject perceived a signal when there was none present.
- Correct Rejection: a correct negative answer for no signal.
- Miss: a negative response to a present signal.
d’: Strength
- Hit > miss (when there is a strong signal)
- Miss > hit (weak signal)
c: Strategy
- Conservative strategy: always say no unless 100% sure signal is present. Bad thing is might get some misses.
- Liberal strategy- always say yes, even if get false alarms.
Strategy B
- Let’s say choose this threshold = 2.
- So anything > 2 will say YES
- Anything < 2 will say NO.
- So probability of hit is shaded yellow, and false alarm is purple.
D Strategy
- D = (d’- B)
- So, let’s say d’ in this example is 1
- 2-1=-1.
- Anything above -1 = YES
- Anything below -1 = NO.
C Strategy
Is an ideal observer. Minimizes miss and false alarm. C = B – d’/2 In our example: it’s 2- 1/2 = 1.5. Anything above a 1.5 is YES Anything below 1.5 is NO.
Bottom-Up Processing
- Begins with stimulus.
- Stimulus influences what we perceive.
- Data Driven.
- No preconceived cognitive constructs of the stimulus (never seen it before).
- Inductive Reasoning.
- Always correct.
Top-Down Processing
- Uses background knowledge influences perception.
- Example: Where’s Waldo?
- Theory driven.
- Perception influenced by our expectation.
- Deductive Reasoning.
- Example: Creating a cube when it’s not there!
- Not always correct.
Gestalt Principle
- Tries to explain how we perceive things the way we do.
- Imagine watching a basketball game on TV.
- Why don’t we tell ourselves that we’re looking at bunch of still pictures rather influence ourselves that it’s some fluid realistic representation of basketball game?
Gestalt Principle: Similarity
- Items similar to one another grouped together by brain.
- Example: The brain automatically organizes these squares and circles in columns, and not in rows.
Gestalt Principle: Pragnanz
- Reality organized reduced to simplest form possible.
- Example: Olympic rings, where the brain automatically organizes these into 5 circles, instead of more complex shapes.
Gestalt Principle: Proximity
- Objects that are close are grouped together, we naturally group the closer things together rather than things that are farther apart.
- Example: We group things close to one another together.
Gestalt Principle: Continuity
- Lines are seen as following the smoothest path.
- Example: You group the line together!
Gestalt Principle: Closure
- Objects grouped together are seen as a whole. Mind fills in missing information.
- Example: You fill in the triangle even though there is none.
Gestalt Principle: Symmetry
The mind perceives objects as being symmetrical and forming around a center point.
Law of Common Fate
Example: if there are an array of dots and half the dots are moving upward while the other half are moving downward, we would perceive the upward moving dots and the downward moving dots as two distinct units.
Law of Past Experiences
- Implies that under some circumstances visual stimuli are categorized according to past experience.
- Example: the English language contains 26 letters that are grouped to form words using a set of rules. If an individual reads an English word they have never seen, they use the law of past experience to interpret the letters “L” and “I” as two letters beside each other, rather than using the law of closure to combine the letters and interpret the object as an uppercase U
Structure of the Eye: Conjunctiva
Thin layer of cells that lines the inside of your eyelids from the eye.
Structure of the Eye: Cornea
Transparent thick sheet of fibrous tissue, anterior 1/6th; starts to bends light, first part of eye light hits.
Structure of the Eye: Anterior Chamber
Space filled with aqueous humour, which provides pressure to maintain shape of eyeball; allows nutrients and minerals to supply cells of cornea/iris.
Structure of the Eye: Pupil
- The opening in the middle of the iris.
- The size of the pupil can get bigger/smaller based on the iris relaxing/contracting respectively.
- The pupil modulates the amount of light able to enter the eyeball.
Structure of the Eye: Iris
- Gives the eye color.
- The muscle that constricts/relaxes to change the size of the pupil.
Structure of the Eye: Lens
- Bends the light so it goes to back of eyeball – focuses light specifically on the fovea of the retina.
- Adjust how much it bends the light by changing its shape, using thesuspensory ligaments.
Structure of the Eye: Suspensory Ligaments
- Attached to a ciliary muscle.
- These two things together form the ciliary body, what secrets the aqueous humor.
Structure of the Eye: Posterior Chamber
Area behind the iris to the back of lens; also filled with aqueous humor.
Structure of the Eye: Vitreous Chamber
Filled with vitreous humour, a jelly-like substance to provide pressure to eyeball and gives nutrients to inside of eyeball.
Structure of the Eye: Retina
- Inside, back area filled with photoreceptors.
- Where the ray of light is converted from a physical waveform to an electrochemical impulse that the brain can interpret.
Structure of the Eye: Macula
Special part of retina rich in cones, but there are also rods.
Structure of the Eye: Fovea
- Special part of macula.
- Completely covered in cones, no rods.
Structure of the Eye: Cones
- Detect color and discern high level of detail in what you are observing.
- Cone shaped.
- Cones are concentrated in the fovea.
Structure of the Eye: Rods
- Detect light.
- Rod shaped.
- MORE RODS THAN CONES (each eye has 120M rods vs. 6M cones or 20x more rods than cones.)
- More important to see light than detail initially! Rods are 1000x more sensitive to light than cones.
Structure of the Eye: Choroid
Pigmented black in humans, is a network of blood vessels that helps nourish the retina.
Structure of the Eye: Sclera
- Usually absorbs by the time the light gets to this.
- The whites of the eye, thick fibrous tissue.
- Attachment point for muscles.
- Extra layer of protection and structure of eyeball.
- Lined with the conjunctiva.
Visual Sensory Information: Transmission
Is the electrical activation of one neuron by another neuron.
Light
- Is an electromagnetic wave.
- Electromagnetic Waves: Violet (400nm) – Red (700nm).
- Highest to lowest wavelength: ROYGBV
Phototransduction Cascade
- What happens when light hits rod/cone.
- Light hits rods (which causes rod turns off) -> bipolar cell (turns on) -> retinal ganglion cell (turns on) -> optic nerve -> BRAIN.
Photoreceptors
Is a specialized nerve that can take light and convert to neural impulse.
Rhodopsin
- Rods contain rhodopsin; cones have similar protein photopsin.
- If light hits a rhodopsin, will trigger the phototransduction cascade.
- Same process happens in a cone.
Visual Field Processing
- How our brain makes sense of what we’re looking at.
- Right side of body controlled by left side, vice versa.
- All right visual field goes to left side of brain; all left visual field goes to right side of brain.
Optic Nerves
From each eye networks the electrical signal to the brain and converge from each eye at the optic chiasm and then break off and dig deeper into the brain
Feature Detection
When looking at an object, you need to break it down into its component features to make sense of what you are looking at:
- Color
- Form
- Motion.
Feature Detection: Color
- Cones Trichromatic theory of color vision: three types of cones. RED (60%), GREEN (30%) BLUE (10%)
- Remember:
- Red objects reflect red
- Green objects reflect green
- Blue objects reflect blue
- Example: If object reflects red -> red light hits red cone -> fire axon potential -> brain is like OH RED!! ),
Feature Detection: Form
- We need to figure out boundaries of the object and shape of the object.
- Parvocellular Pathway: good at spatial resolution, and color. Can’t detect motion, only stationary.
- It’s cones responsible.
- Acronym: Pink Pyramid (a type of “form”/”shape”) = Parvocellular pathway
Feature Detection: Motion
- Magnocellular pathway: has high temporal resolution (think time, motion) resolution [encodes motion].
- But has poor spatial resolution; no color).
- It’s rods responsible.
- Acronym: Motion = Magnocellular pathway
Parallel Processing
Detect/focus all information (color, form, motion) at same time.
Audition
- Our sense of sound.
- For us to hear sound we need two things:
- Pressurized sound wave (a stimuli):
* Example: In between your hands are a bunch of air molecules, and when hands move towards each other, there is less space so the molecules compress and there is a higher pressure. The air molecules are becoming pressurized. - Hair cell (a receptor, located in the cochlea)
Sound Path Steps
- Enters outer part of ear knows as pinna.
- Goes from Pinna to the auditory canal knows as external auditory meatus.
- From auditory canal hits the tympanic membrane known as eardrum. *As pressurized wave hits eardrum, it vibrates back and forth, causing 3 bones to vibrate in this order:
- i. malleus (hammer)
- ii. incus (anvil)
- iii. stapes (stirrup) *[acronym: MIS]*
- Stapes attach to oval Window and vibrates back and fourth.
- As it gets vibrated, it pushes fluid and causes it to go in/around cochlea.
- At tip of cochlea (inner most part of circle), where can the fluid now go? It can only go back, but goes back to the round window (circular window) and pushes it out.
- As hair cells (cilia) move back and forth in the cochlea – electric impulse is transported by auditory nerve to the brain.
Cochlear Implants
- A surgical procedure that attempts to restore some degree of hearing to individuals with sensorineural narrow hearing loss – aka
nerve deafness. - Sound -> microphone -> transmitter (outside the skull) sends info to the receiver (inside skull). Then it sends info to the stimulator, into the cochlea, and cochlea converts electrical impulse into neural impulse that goes to brain. Restores some degree of hearing.
Amplification
- Is up-regulation.
- Opposite of sensory adaptation.
- Example: Light hits photoreceptor in eye and can cause cell to fire. When cell fires AP, can be connected to 2 cells, which also fire AP and so on. By the time gets to the brain, it is amplified.
Kinaesthesia
- Is talking about movement of the body.
- Kinaesthesia is more behavioral.
- You teach yourself how to move to successfully complete the task at hand.
- Example: “If I move in this direction, I will hit the baseball.
Nocireceptor
- Ability to sense Pain.
- Nociception is SLOW.
- We rely on the TrypV1 receptor to sense pain.
Thermoreception
- Ability to sense temperature.
- Thermoreception is SLOW.
- We rely on the TrypV1 receptor to sense temperature.
- There are thousands of these in membranes.
- Heat causes a conformational change (change in physical structure) in the protein.
A-beta Fibres (Nerve)
Fast ones are thick and covered in myelin.
A-delta Fibres (Nerve)
Smaller diameter, less myelin.
C Fibres (Nerve)
Small diameter, unmyelinated (lingering sense of pain).
Gate Control Theory
- Of pain asserts that asserts that non-painful input closes the “gates” to painful input, which prevents pain sensation from traveling to the central nervous system.
- Therefore, stimulation by non-noxious input is able to suppress pain.
Trichromatic Theory of Color
- This theory says that we have cones receptive to three colors:
- Red
- Green
- Blue
- These colors are mixed together and we percieve colors.
Opponent Process Theory of Color
- This theory states that we have cones that percieves four colors:
- Red
- Green
- Blue
- Yellow
- Red and Green oppose each other
- Blue and Yellow oppose each other
- Black and White oppose each other
Pheromones
- Why do dogs pee on fire hydrant? There are molecules released in the urine, which can be sensed by other animals through the nose – pheromones.
- Pheromone is a chemical signal released by 1 member of the species and sensed by another species to trigger an innate response.
Lateral Geniculate Nucleus
- is a visual information relay center in the thalamus.
- Detects and interprets information from the retina and passes it on to the primary visual cortex in the occipal lobe.
