Unit 3: Sensation and Perception

Bottom-up processing

-Involves identifying a stimulus by analyzing the information available in the external stimulus -Start looking at little pieces, then bring those pieces together to look at the big picture

Great amplitude means:

Bright colors, loud sounds

Example of sensory interaction

Different colored ketchups might not taste the same to you even though they're the same thing

Small amplitude means:

Dull colors, soft sounds

Short wavelength means:

High frequency, bluish colors, high-pitched sounds

Example of an afterimage

If you stare at an American flag that's teal, yellow, and black, then look at a white wall, you will see the flag as red, white, and blue

Explain the visual cliff experiment and the findings of Richard Walk and Eleanor Gibson

It involved a glass table with a division in the middle. On one side was a checkered pattern, and on the other side the pattern was on the ground so even if the baby was safe on the glass, it looked like they would fall to the ground. They determined that human and animal infants will avoid crossing over an apparent drop-off and thought babies learned to be afraid of heights.

Simplicity

People tend to organize forms in the simplest way possible (a venn diagram is 2 circles overlapping, not 2 fat crescents with an oval in between)

Figure ground

Perceptions have 2 parts: an object that stands out in good contour and an indistinct homogenous background (ex. you can't see the tree and the lion/gorilla at the same time - one is always in either the foreground or background)

Where does Trichromatic theory take place in the process of vision?

Photoreceptor level (cones)

Gate control theory

Pressure is able to travel faster to the brain than the stimulus of pain

What did the work of David Hubel and Torsten Wiesel contribute to our understanding of feature detectors?

They studied them and helped us determine that different parts of the visual cortex allow us to see different things

Supertaster

-25% of population -Abundance of taste receptors - better at sensing taste

Embodied cognition

-Bodily sensation influences cognitive processes -If you're on a date and someone's holding their hands around a cold drink, their personality is received as cold

Kinesthetic sense (proprioception)

-Position of body (knowing the orientation of your body without looking) -Control - coordinate movement -Cerebellum

How does subliminal relate to the absolute threshold?

Always below the absolute threshold

Example of context effects

Ba vs. Va video - same sound both times, but the way the person visually enunciates changes what you hear

Long wavelength means:

Low frequency, reddish colors, low-pitched sounds

Relative height

Near objects are low in the visual field, more distant objects are higher up

Explain touch's route to the brain

Nociceptors to the somatosensory cortex

How does the gate control theory work?

Non-painful sensory input can dampen or block painful sensations from reaching the brain

What are some examples of difference threshold/just noticeable difference?

Noticing the difference in brightness between 2 lightbulbs

Blindsight

People who are blind but have some sort of ability to perceive visual information

What are the types of touch we experience?

Pressure, pain, cold, warmth

What flavors do we experience?

Sweet, salty, sour, bitter, umami

Touch

Tactile sense

Phantom limb

The perception of feeling in an appendage even after it has been removed from the body

Linear perspective

The principle that the size of an object's visual image is a function of its distance from the eye. Thus, two objects appear closer together as the distance from them increases and appears to converge on the horizon

Example of vestibular sense

Walking across a balance beam

Explain the rubber hand illusion

When a rubber hand is stroked at the same time as someone's real hand, the brain thinks that the rubber hand it sees is its actual hand and it can experience sensation

Monocular depth cues

-A depth perception cue using only one eye -Helps us understand how far away an object is -Linear perspective, texture gradient, interposition, motion parallax, relative height, relative size, light and shadow

How does the sense of smell change with age?

-As we age our sense of smell gets worse -Also the reason why as you get older you like foods you didn't like as a child

Synesthesia

-Cross-wiring of senses -When they experience one sensation they simultaneously experience another -Often it's color associated with letters/numbers

Binocular depth cues

-Depth cues provided by both eyes -Takes visual fields from both eyes and blends them together -Because your eyes are in two different locations on your face, there is a discrepancy between the images each eye sees -The only binocular depth cue we have is retinal disparity

Vestibular sense

-Detect motions of the head -Balance - coordination -Semicircular canals

What are some examples of Weber's Law?

-Dim lights - you don't have to change the brightness much to notice a difference -If lights are already bright, you have to change the brightness a lot more to notice a difference

Rods

-Higher concentration in periphery -Register information in low light -Only allows us to see in black/white

Explain scent's route to the brain

-Inhale molecules, reach sense receptors through nasal cavity -Goes through olfactory bulb in brain instead of thalamus like all other senses

Top-down processing

-Involves identifying a stimulus by using the knowledge we already possess about a situation -This knowledge is based on past experience and allows us to form expectations about what we should perceive -Connects to stereotyping

Cones

-Located mostly in the center -Only work well in well-lit areas -Allows us to see in color

What are some examples of signal detection theory?

-Noticing if a cell phone is vibrating -You're baking cookies and waiting for the timer to go off while watching Grey's Anatomy. You're able to tell the difference between the timer and the heart monitor on the show

How does Trichromatic theory explain how we see color?

-One responds best to short wavelengths (blue), one to a medium wavelength (green), and one to a long wavelength (red) -Any other color is perceived by the mixing of signals from the cones

Opponent Process theory

-Opposing retinal processes enable color vision -Developed because we had no explanation for afterimages -Doesn't refute Trichromatic theory but builds on its weaknesses

How does Opponent Process theory explain how we see color?

-Opposite colors work simultaneously at the ganglion cell level after the cones are excited -After staring at one color, we often see the oppposite color appear (ex. ganglion cells get excited seeing blue, then when looking away they balance out by seeing yellow)

Signal detection theory

-Our ability to detect the presence of a stimulus -Predicts how and when we detect the presence of a faint stimulus amid background stimulation

Perceptual set

-Readiness to perceive a stimulus in a particular way -Creates a bias that somehow causes a person to interpret their sensory input in a particular way

What are some examples of absolute threshold?

-Taste __tsp of sugar in a gallon of water -Detect the scent of perfume throughout 6 rooms

Selective attention

-The ability to focus on one stimulus while excluding other stimuli that are present -Ex. murder mystery video where you miss the 21 changes

Depth perception

-The ability to perceive the relative distance of objects in one's visual field -When judging depth perception, we can use both (binocular) or even just one eye (monocular) to help us make sense of what we see

Cocktail party effect

-The ability to tune our attention to just one voice from a multitude of others -In a crowded room you'll get distracted by someone saying your name even if you weren't paying attention to them before

Absolute threshold

-The minimum amount of a stimulus you're able to detect 50% of the time

Retinal disparity

-The slight difference between the right and left visual images -In the retina the two images are automatically compared and, if sufficiently similar, fused

How does color blindness highlight an issue with Trichromatic theory?

-Trichromatic theory says that color blindness is a deficiency in one or more of our 3 types of cones. The most common deficiency (red/green) occurs when people have a problem with either long or medium wavelength cones -Fails to account for people who have a red/green deficiency and can still see the color yellow when red+green=yellow

How does top-down processing make us vulnerable to illusion?

-We can read words with the letters in any order as long as the first and last letter are in the right place -The picture where you see a white triangle even though it's not clearly outlined -You hear audio and it sounds like gibberish, but if you're looking at words, you can suddenly hear those words

Trichromatic theory

-We have 3 types of color receptors (cones) that help us see -Red, blue, and green each respond best to a particular wavelength of light

Inattentional blindness

-When people focus on a task that demands their attention, they often fail to notice unexpected objects and events that occur in full view -People think they would notice these changes but in reality they don't

Example of perceptual set

-When you're home alone every noise you hear is a serial killer -Depending on the story you read you will see different pictures when shown an image

Transduction process

1. Stimulus energy (light, sound, etc.) 2. Sensory receptors 3. Neural impulses 4. Brain Sensation --> perception

How does smell influence our sense of taste?

A lot of our sense of taste is based on our sense of smell

Afterimages

A visual sensation that occurs after a visual stimulus is removed

Phi phenomenon

Apparent motion resulting from an orderly sequence of stimuli (ex. a gif, christmas lights that look like they're moving but really it's just lights switching on and off)

Stroboscopic movement

Appearance of motion when the stimulus is not viewed continuously but in separate distinct stages (ex. a flip book)

Motion parallax

As we move, objects close to us appear to be moving in the opposite direction at a fast pace creating a blurry image

Example of bottom-up processing

Bottom = peach emoji MRI of a peach that is built layer by layer

Example of change blindness

Continuity errors in movies: someone's hair is behind their shoulder in one scene and in front in the next scene, but it's hard to notice because our attention has reset

Stroop effect

Disconnect between 2 stimuli (ex. if there is a list of color words and each word is written in a color that doesn't match the word, it's very difficult to just say the color and not the word)

Connectedness

Elements connected to one another by uniform visual properties are perceived as a single group and interpreted as being more related than elements that aren't connected (basically if you see a shape like O-O you will see glasses or a barbell instead of circle-line-circle)

Example of kinesthetic sense

Field sobriety test: officer asks you to close your eyes and alternate touching your nose with each hand

Change blindness

Form of inattentional blindness in which one fails to notice obvious changes in the environment

Where does Opponent Process theory take place in the process of vision?

Ganglion level

Relative size

If separate objects are expected to be of the same size, the larger ones are seen as closer

What is the optic chiasm and what happens there?

It's the eye's version of the corpus collosum. The left visual field goes to the right visual cortex and vice versa. If someone's corpus collosum was severed, it wouldn't affect their sight because of the optic chiasm

Why do we have a blind spot?

It's where the optic nerve is leaving the eye so no photoreceptors are there

Subliminal

Low to absolute threshold - things you kind of notice but not really

Photoreceptors

Made up of rods and cones

Interposition

One item blocks the view of items behind it, therefore allowing us to view the unobstructed object as closer to us

Sensory interaction

One sense influences our perception of another

Proximity

People tend to organize objects close to each other into a perceptual group and interpret them as a single entity OO OO OO OO OO OO OO OO OO

Similarity

People tend to organize objects with similar qualities into a perceptual group and interpret them as a whole OO II OO OO II OO OO II OO OO II OO OO II OO

Continuity

People tend to perceive objects in alignment as forming smooth, unbroken contours

Weber's Law

Proportion a stimulus needs to change in order for it to be detectable

Explain taste's route to the brain

Receptor cells on tongue (reproduce every 2 weeks)

After an image hits the retina? In what order does the information travel to get to the brain?

Retina --> rods/cones --> bipolar cells --> gangrion cells --> join to form the optic nerve

Prosopagnosia

Same as face blindness: you can see features of a face, but you can't understand/recognize the entire face (you struggle understanding the whole picture)

Light and shadow

Shadows often appear on the parts of objects that are more distant

Examples of perceptual constancy

Size: in a picture where pigeons look the same size as cars, we know they aren't actually the same size Color: We perceive colors of objects as being constant despite a range of changes (ex. you know what color your house is even when it's dark) Shape: Perceived shape of an object remains constant despite changes we see (ex. as a door opens and appears to be getting thinner, we know it's still a large rectangle)

Feature detectors

Specialized neurons that reside within the visual cortex and allow us to see tiny specific aspects of things (ex. right angles, curves, etc.). Combined, this forms the whole picture

What are supertasters sensitive to?

Spicy things

How does our brain compensate for the missing information within the blind spot?

The brain fills in missing information because it combines both eye pictures

Frequency theory

The brain hears pitch by monitoring the frequency of neural impulses. The whole basilar membrane vibrates with the sound wave, triggering neural impulses to the brain at the same rate as the sound waves - best explains how we hear low pitches

Context effects

The context in which something appears guides peoples perceptual hypotheses

Difference threshold/just noticeable difference

The minimal change in stimulation that can be reliably detected 50% of the time

Sensation

The process by which we receive information from our environment. Happens in the sense organs

Perception

The process of selecting and identifying information from the environment (interpretation of our experience). Happens in the brain

Transduction

The process of selecting and identifying information from the environment (interpretation of our experience). Happens in the brain

Gestalt

The tendency to create a perception that is more than simply the sum of the available sensory input

Closure

The tendency to perceive an incomplete figure as a whole

Texture gradient

The texture of a surface receding in the distance changes in clarity, blurring at further distances

Example of inattentional blindness

Video where you're supposed to count the number of times a basketball is passed but you don't notice a gorilla walking through

Place theory

We hear different pitches because different sound waves trigger activity at different places along the basilar membrane - best explains how we hear high pitches

Perceptual constancy

We understand there are aspects of items that don't change even if our perception of it changes

Who are the two psychologists credited for the ideas of difference threshold and Weber's Law?

Weber and Fechner

How do we utilize gate control theory when we experience pain?

When you hit your elbow you rub it to try to alleviate the pain

Example of top-down processing

When you see that painting made up of fruit you see a face

How can the definition of gestalt be stated in a simpler way?

Your perception of something is different than just piecing together the stimuli you're experiencing

How can culture and experience influence what we perceive?

Zulu culture - not a lot of straight lines/right angles, so the people aren't as affected by optical illusions involving those shapes