Sensation & Perception - Page 1 Notes

Sensation

Definition: The process of gathering information from the environment through sensory organs (nose, eyes, etc.) and transmitting it to the brain.
Sensation is the initial input from the outside world that travels inward via sensory structures to the brain.

Perception

Definition: How the brain interprets sensory input.
They work together and commingle as a team; you can't have one without the other.

Sensory Receptors and Neurons

Neurons are stimulated by the outside world rather than by other neurons.
Example: Sensory receptors in the eyes take in information from light and convert that into neural signals.
Touch receptors are activated by pressure.

Thresholds

Thresholds refer to the limits at which sensory systems detect or discriminate stimuli.

Just Noticeable Difference (JND)

The smallest difference between two stimuli detectable 50% of the time.
Example: How much of a water temperature change in a shower does it take for your skin receptors to realize something has changed?
Formal representation: \Delta S \text{ is the smallest difference such that } P(\text{detect}) = 0.5.

Absolute Threshold

The lowest level of stimulation a person can perceive 50% of the time (the bare minimum to activation).
Formal representation: S_0 \text{ such that } P(\text{detect}) = 0.5.

Dealing with Constancy

Habituation: Tendency for your brain to stop responding to constant changes within the environment, tuning out other background details.
Sensory Adaptation: Tendency of sensory receptor cells to become less responsive to stimuli; they may signal the same exact information over and over again, but your brain may stop noticing it.

Transduction:

The ability for the brain to actual convert (the conversion) between external energy to an actual signal in your brain.

Perception:

An important part of perception is being able ti recognize in context what something is to think and analyze it.

How are these two elements, sensation and perception, related to survival of the fittest?

Being able to pick up on certain things (such as being able to spot a banana, or hearing sounds of a truck coming) have been ale to protect us and keep us alive as we've evolved.
Certain species may have evolved to have different traits that are able to detect unique things that increase their chance of survival (ex: elephant ears have adapted to pick up on low frequency noises that may indicate predators are on the loose)

Extrasensory perception (ESP):

The false recollection that one can have a perception without having any sort of sensory sensations beforehand (aka mind reading, telepathy, ect)
Falls into the category of parapsychology, which is the study of topics that fall outside of mainstream psych. (Often to be affiliated with psuedopsychology)

Absolute threshold:

The minimum amount of stimuli for it to be detected at least half of the time.
Ex: You can hear your dog bark in the room next to you, but can you hear it breathe?
Diversity is a factor: For hearing especially, the average threshold is around 20 hz but there are certain factors such as gender, ethnicity, age, and occupation.

The difference threshold:

How much stimuli in a change does it take for you to notice at least half of the time?
Weber-Fencher law states that the bigger the original amount, the bigger the new difference will have to be before you notice (ex: Bench pressing. If you already can bench a hundred pounds, it usually takes you a good couple of extra pounds to notice the weight is off)

Sensory adpaptation:

When your external stimuli has remained the same for a good while, you may eventually become accustomed to the stimuli therefore you do not pick up on it as much.
Ex: You've lived in your house your entire life so you do not think there is a particular smell too it but when your friends come over, they say that it smells like vanilla and you've just become accustomed to it overtime that you didn't even know/ remember!

Perceptual constancy:

Being able to recognize the fact that although there are slight changes in stimuli or something you've known, your brain has the ability to detect that that still has the same properties.
Ex: Kicking a ball that comes closer to you. Although it looks like it changes size asset's coming closer and closer to you appearing "bigger" your brain automatically knows that it remained a consistent size.

Cocktail party effect:

In selective attention, your brain has the ability to tune out stimuli of a sense to focus on a specific stimuli within that same sense.
That means if you're listening to a professor speak, your mind is able to concentrate on what she's saying while there may be other hearing stimuli such as chit chat, YouTube videos, and sounds of students shuffling in their seats and walking in the hallways.
Studies show that humans tend to respond better using the cocktail party effect when they pick up on stimuli that either resonates with them or applies to them. For example, a group did a study on this with patients just coming off of anesthesia and used two different methods to wake their patients up: In one method they called "Patient" and in the other they called their name. It showed that the patients who were called by their true name responded quicker to the stimuli.

Sensory blending:

Your brain uses a combination of different stimuli from all different senses and conjoins them to influence what you think (and/or feel from it).
Ex: When you are sitting in a movie theater, your eyes watch as the characters speak on the screen but the reality is that the words you are hearing are coming from speakers off to the side. Your brain combines them to believe that the actual characters are speaking in realtime.

McGurk effect:

Sometimes sensory stimuli do not "add up"
One study had a child mumble the words "ta ta" with a T while the audio playing over the video sounded like "ma ma" with the M
Another study dyed drinks different colors to see how sight perception can outwit other senses: For instance if a real cherry flavored drink was dyed orange, some participants were tricked into believing the drink was orange flavored.
Your sight often overpowers all other stimuli.

Sensory conflict theory:

When one stimuli suggests one thing while other stimuli suggest the opposite or a different sense.
Best example is motion sickness: When you're in a car, your sensors indicate that you are sitting still but when you look with your vision out the window or hear the sounds of your car passing by objects on the highway, you know you're moving.

Bottom-down processing:

When a new situation arises and there is stimuli that is less familiar to you, you tend to take in stimuli in a foreign way, learning as you go.
For instance, when you first arrive at college, you've never been here before so walking to classes and experiencing dining halls for the first time was bottom-up.

Top-down processing:

By stimuli, you can almost "guess" what comes next
From memory or past situations, you may be able to infer what happens when the sensation kicks in.
An example would be when you are listening to your favorite song and the music is paused: You continue to keep signing the lyrics without having to hear the song because by memory, you already know what comes next.
Bias: When you have a perceptual set, our past experiences may set the stage for how we take the info.
Your basic understandings oh what the world can be may have influence on what you see (I.E. people who believe in big foot and that kind of stuff may look at some submitted photo of supposedly "Nessie and think its reallyhim”
Contextual effect: Using context when it’s not sure what to interpret, will look for speciic clues.

Gestalt (Organized hole):

We are trying to interpret the world in an organized hole rather than fragments.
Figure-ground princple: Organizes sensory input into.a figure

Perceptual set:

Going off of top-bottom sensations, your brain has a built in "toolkit" based on prior knowledge and experiences that have built up overtime to handle or respond to certain situations.
For example- people who have been the victim of past trauma such as rape or abuse may flinch when they hear a noise due to what had happened to them in their past.
Change blindness- When you fail to realize something has changed although it is clear.
Innattention blindess: Failing to realize a change or pick up on something within your field of vision because you were focused on something else.

Vision:

Humans and primates have two different "neural pathways" in determining visual stimuli.
Ventral identifies what the object is.
Dorsal defines where it is coming from.

Cornea:

Thin "clear" layer of lens on top of the eye
Cannot "bend" its lens in order to manipulate images, but it does a little bit of refracting (bending) to make images clearer.
Serves mainly for protection from scratches.

Iris:

Circular muscle with the color
Pulls at the pupil, which can change sizes allowing light to get through the eye.
Pupil extends in darker scenes while it dilates in very bright atmospheres.

Lens:

Internal; eye, is allowed to change its shape of curvature in order to decipher images at differing distances.
Cataracts puts a cloudy film over the lens, similar to how it feels to drive with foggy spots on a windshield.

Retina:

"Screen" in the back of your eye that receives external sight stimuli and sends it to your brain via the optic nerve.
Path begins at retina, to the optic nerve, thalamus and finally the optic nerve.
Transduction: The process of translating visual signals from outside into internal brain messages.

Rods vs. Cones:

Rods are specialized cells in the retina that allow us to see light in darker situations. (More abundant)
Cones are specialized cells in the retina that allow us to see bright colors in higher situations. (Less abundant)

Fovea:

Area in the eye where there are only cones: No rods
Cones are all densely packed in structures, and the more dense thy are the more your brain can pick up on detail and visual sensations.

Different types of eye jumps:

Scaddic: Jumping from one sight of vision to another. In between "jumps" are called fixations.
Compensary: Keep your eyes focused on a chosen image (even if you move your head or field of vision, your eyes remained locked on it)
Vergence: Eyes move in unison

Depth perception:

Your ability to determine how far or large an object is or both through perpetiv.

Monocular depth cues:

Indicate depth perception only when using one eye
Ex: 2-dimesnional linear perspective in art, converging lines.

Binocular depth cues:

Indicate depth when you use both of your eyes
Necessary for analyzing 3-dimesional images
Retinal despariy: A comparison of the messages sent from each eye of the difference between two images.\

Hue:

Measure of the wavelength of that specific shade you are measuring with your eye.
Your human eye can detect 400 - 700 nm in length, outside of that are infrared and ultraviolet.
Sometimes the objects you are looking at surrounding the hue have influence on what hue you pick up from it.

Three types of cones:

Short-wavelength sensitive (S) cones- pick up bluish hues.
Middle-wavelength cones (M) - Greenish colors
Long-wavelength sensitive (L) cones

Figure-ground organization:

Ability to identify which objects are part of groups and serpeate
Distinguishing object from bacgkround
Usually determined with depth- object in front.
Gestalt: Organized hole that you consider to be different than its individual parts.

Proximity: How close objects are together (further they are away the less likely iy is to form a gestalt)

Similarity: If objects have features that are universal, the more likely they are to be associated together.

Changing fate: If objects change together rather than their own,

Connectedness: Objects are touching, meaning they are more likely to be closely related,

Closure: UIf one part is missing an otherwise assumed shaped, your mind can make up the missing "puzzle piece"

Hearing

This is called audition:

What you hear

Hearing is an essential survival instinct.

You can only see so much with your eyes, most times just directly what’s in front of you. However, with your ears, you may pick up on peripheral stimuli from all around your body making it easier to detect certain things without literally having eyes everywhere.

Structures of the outer ear:
Pinna: The word for basically the enitre outer ear structure (that you can touch with your hands). It is responsible for collecting vibrations and literally “funneling” them towards the inner ear where they are interpreted.
Typanic memberane: More commonly known as the eardrum. Takes in soind waves from the pinnacle and amplifies them (to nearly 17 times the sound of their original intensity). It is held together by small “connective” bones called osicles.
Cochlea: A fluid-filled organ in the inner ear that relays sound vibratiosn to the auditory nerve to be sent to the brain. The fluid fillled sacs of the cochlea create official vibrations to be sent out from the ear.

Looking at different forms of “noise”:

Pitch: Pitch is decsribed by the frequency of vibrations. More vibrations »higher frequencies»higher pitches.
Your ability to interpet a pitch depends on some factors. For example: age. The older you get, the more the ear loses it’s ability to interpret pitches of higher frequencies.
Place theory: Explains that you have tiny hair cells in the cochlea placed at different locations that are made to pick up on pitches.
Frequency theory: Neural impulses sent via the auditory nerve are sent at different frequencies, resulting in a pitch that you hear. (This theory however explaisn that the frequency remains unprocessed through the inner ear and are only translated in the midbrain).

Sound localization:

your brain has the ability to deterime the absolute location or direction that a sound is coming from.
It will synthesize a discrepancy that interprets the difference between the amount of time it took to reach each ear. (For ex: If the sound is directly in front of you, discrepancy = 0 but if it is anywhere remotely left or right of you there will be some difference).
Not only does localization include a sound hitting one ear before the other, the ear that is closer to the source of the noise will indicate localization too.

Diversity in music:

Certain culutures tend to incorport=ate differentials in the scake of their music.
Studies show that when you become accustomed to one scale within your culutre, you are more prone to favor melodies that align with thats acle.

What is olfaction?

Olfaction is your sense of smell
Your nose has over 400 million different kinds of receptors, making any smell that even seems simple to be very complex.

Aqueous humor: When you blink, your eye is kept nice and lubricated rather than sandpapery.

Iris: Colored part of eye, job is a muscle that contracts an extends to allow light into the eye.

Lens: Behind pupil and iris, focusing light in direction it should go. Takes light info and shines it back to the back of the eye.

Vitrious humor: Jelly-like substance that provides eye with fluid but most importantly keeps its structure

Structure of the retina:

Where key sensory receptor cells interpret light and turn them into a neural signal.
Rods & cones
Rods are sensitive to brightness (Taking message and telling how bright something is around you)
Cones: Sensitive to co,or
Rods arr located pretty much all around the retina, disperesed
Bipolar cells: They receive signal from the rods and cones of the eye, pretty much just relaying the information
Ganglion cells: Axons form optic nerve
Blind spot: Wahrere the optic nerve leaves the eye without any rods or cones, your brain can kind of fill that space in for you.

2 Theories of Color Perception
* Three types of cones sensitive to a particular type of color: Blue, red, green

After-image: zOne of the greatest problems with the trichromatic theory.

Opponent proceeds theory:

There are fur primary colors paired up between red-green and blue-yellow
Stimulate one color and the other is inhibited
When one is overstimulated, once it its given a break it inhibits the other golor

Hearing structure:

Pinna - "Fleshy part" that sticks out to side of the head, looks like a funnel because it catches sound waves and brings them into the ear
Auditory canal: Channel where sound waves travel before hitting eardrum
Erdrum: Works very similar to an actual drum
Smallest bones in body (Hammer anvil stirrup) work as a chain of vibration to the inner part of the ear.
Cochlea: Feels the vibrations and that translate them into detectable vibrations
Cochlear implant: Captures sound waves by going straight to the auditor nerve.

3 theories of perceiving pitch:

We don't cater;;y know
Pitch depends on where stimulated hair cells are places on organ of Corti
Frequency theory: Faster vibrations mean high pitch, slower vibration means low putch
Volley principle: Groups of auditory neurons take turns firing/

Taste:

Taste buds: taste receptor cells
Taste buds are not just on your tongue, they are all over your mouth
there aren't specific taste buds for a certain taste
Each "bump" has hundreds of little tastebuds
Taste buds hace receptor sites that take the chemical from our food and they kick in ti the receptor site is a signal.

Smell (Olfation):

Sensory receptor cells ar sin the sinus cavity and dangle like hair waiting for air to pass by holding chemicals
Smell is the only sense that does not send to the thalamus'Smell sends information straight to olfactory bulbs.
internostril comparison is similar to that of sound localization in hearing except nostrils can detect the location of a certain scent in relation to their nose by using deduction to determine which nostril it hit first.

Cilia:

Each scent receptor has about 20
They are tiny “hair” like particles that pick up certain chemicals unique to scents and pass them onto the olfactory bulbs - 2 brain structures located on the underside of the brain bridging the nose.
Those bulbs then carry that information off to the olfactory cortex which is located in parts of the cerebrum and amygdala

Scent recall:

When scent is detected in the amygdala it may respond with a strong signal.
A smell that has some sort of emotional or physical connection to you will repsond very strongly to the signals, whereas something that has little importance or meaning will have a more mild undertone.

There are two kinds of smell:

Odors that you can detect
Pheromones which are the chemical substances linked to the scent, but you don’t necessarily “smell” them. (Sometimes these chemicals can subconsciously influence your behaviors - esepcially when it comes to sexual attraction)
Male sweat hormones contain a pheromone which studies have shown can trigger women attraction.

Hyposmia: Often temporary limitied ability to detect odors.

Amnosia: Often temporary inability to detect odor at all.

Studies show and indicate that loss in sense of smell is more prevalent among older adults, especially populations with life-altering illnesses like Alzheimer’s.
Results of a study indicate that women are much stronger at indetifying certain smells.

Gustation:

The sense of taste (Comes from latin word “pleasurable”)
Your taste buds are the receptors and there are four indefintie qualitis on each receptor: One that analyzes sweet, ne that analyzes sour, one that analyzes salty, and one that analyzes bitter. The fitfth in question is called “umami”, which is basically savory.
Everyone has the same taste buds, but sometimes, depenidng on the person, each indiviudal quality may have varying degrees. (For ex, someone may not be as sensitive to sweet but may be really sensitive to sour receptors)
Studies indicate that a majority of supertasters (people with ehanced sense of smell, often very strong) respond more extremely.

Somatosensory: Your skin has three different types of receptors in the dermis!

Mechanoreceptors: Allow you to analyze touch
Thermoreceptors: In analyzing temperatures
Nociceptors: detects pain
Your touch receptors can determine not only when something is touching you but also pressure and if it is moving against your skin.

Touch tests:

Grating orientation - You run your hand against a surface of varying ridges and bumps.
Two Point Threshold Set- Places two points on your skin (placed at some distance) and determines in different spots of the body how long or dtsant these have to be in order for you to detect they are two different points.

Temp receptors:

Thermoreceptors cannot detect both hot and cold temperatures simultanoesuly. They are orgsnized into groups - hots and colds.
We have overall plenty more cold receptors than hots
Typically cold receptors tend to get the message to the brain much faster.

Touch:

Skin senses, pressure, temperature, pain
You have different receptor sites in your skin to sense these
Kinesetic sense: Location of body parts in relation to each other, you have receptors in your brain that can tell you where your muscles are and how they move so you can "move your body in space"
Vestibular sense: movement and body position, uses cochlea to determine where your body is in space

Kinestetic and vestibular senses:

Come together to tell you where your body is, what it is doing in relaiton to speed, and movement, and influences balance.
Oftentimes if you are moved and your eyes are closed, you’ll still be able to tell something is off with your two senses.