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