Sensation and Perception

Question 1

Sensation

Answer 1

-Stimulation of sensory organs
-what our senses do
-an external stimulus hits our sensory organ

Question 2

Transduction

Answer 2

Translation of physical energy from the environment to neural signals
-an external stimulus hits our sensory organ
-sensory organ changes for our brain to process this info

Question 3

Perception

Answer 3

-processing, organization, and interpretation of sensory input
-what our brains do - internal representation of world
-experiences can play a role in what we perceive but this is not what is actually true 100% of the time

Question 4

Questions asked about sensation and perception

Answer 4

-do you believe you are in touch with reality right now?
-how do you know where you are and what is happening right now

-examples:
-what we see and what we think
-how do we know what is happening right now
-how do we know we are in a classroom
(our contact with the world is filtered through our sensory system)
-why did I not sit in a chair someone was already sitting in (the brains sensory experiences with what we already know, which is a complex process)
-our brains adapt to knowledge and social norms
-what we think is objective is not actually as objective as we think

Question 5

Are we in touch with reality?

Answer 5

“What is real? How do you define real? If you are talking about what you can feel, what you can smell, what you can taste and see, then real is simply electrical signals interpreted by your brain. This is the world that you know.” - Morpheus’s answer to Neo in The Matrix, 1999

-in the matrix, humans are hooked up to machines, which fool them into having experiences that are not actually happening

Question 6

Are we in touch with reality example:
-plato and the allegory of the cave

Answer 6

-The story of prisoners trapped in a cave, only able to see shadowy images cast against the wall in front of them by unseen people holding up objects behind them, was meant to represent the manner in which most people, relying only on their immediate senses, could understand only a little of the nature of reality.

-appearance of what we see as real are false
-we will never access what is “real”

Question 7

Individual differences in sensing reality:
-taste

Answer 7

-supertaster vs regular taster

-genetic differences of the number of tastebuds
-some people are regular tasters and taste food to a moderate extent
-some people cannot taste anything (extreme)
-a super taster is prone to bitterness and repulsion. For example, hot pepper is unbearable

Question 8

Psychophysics

Answer 8

Psychophysics is the study of the relationship between physical stimuli and psychological experience

-what can we detect? How intense does it have to be? How sensitive are we? At what point can we detect a stimulus?

-Key principle: We do not experience reality directly!

Question 9

Absolute Threshold

Answer 9

Minimum stimulation necessary to detect a stimulus 50% of the time

-can you detect salt in a glass of water? (how much salt did you have to add to be able to tell there was salt about 50% of the time)
-differs across situations and individuals

Example:
-1/2g is detected 20% of the time
-1g is detected 50% of the the time
-2g is detected 85% of the time

-Absolute threshold is not constant/stable (it depends on mood, day, our own absolute threshold, and many other factors)

Question 10

Difference Threshold

Answer 10

The smallest difference between stimuli that can be reliably detected 50% of the time
-just noticable difference
-it depends on the intensity of the original stimulus (if the TV is loud and you turn the volume up by 1 decibel, you won’t be able to tell. But if you had the TV originally at a low volume and increased it by 1 decibel, the change is more obvious)

-e.g. how much did you have to turn the TV volume down before you can tell it is lower?

Question 11

Weber’s Law

Answer 11

-Weber’s Law explains how we notice changes in things like brightness, weight, or sound. It’s not about how much is added or removed, but about the proportion of change.
-It is not about the absolute amount of a stimulus that is added/taken away… it is about the proportion

-In order to notice a difference: the two stimuli must differ by a constant proportion
(To detect a difference, the change must be a certain percentage of the original amount):
-Light needs to change by at least 8% to be noticed.
-Weight needs to change by at least 2% to feel different.
-Sound needs to change by at least 0.3% to be heard as different.

-E.g. this means that if you’re holding a small weight, adding a little more might be noticeable. But if you’re holding a very heavy weight, you’d need to add a lot more to feel the difference!

Question 12

Visual Illusion

Answer 12

-an elephant that appears to have 8 legs

-A visual illusion is when your brain misinterprets what your eyes see, making something appear different from reality. This happens because the brain processes visual information in certain ways, sometimes leading to errors in perception.

-people find this image jarring and hard to look at because it conflicts with our expectations and knowledge about the world

Question 13

THe MHn RHn

-read it as The Man Ran

Answer 13

The “THE MAN RAN” example is a case of perceptual organization—how our brain groups and interprets information. Even if the words are spaced strangely or letters are missing, your brain automatically fills in the gaps to make sense of what you see. This is similar to Gestalt principles, which explain how we organize patterns and incomplete information into meaningful wholes.

-This example shows how our brain actively processes information, not just passively receiving it!

Question 14

Bottom Up vs. Top Down

Answer 14

Bottom-Up Processing:
-Taking individual bits of sensory information and using them to construct a perception

Top-Down Processing:
-Our perceptions that are influenced by our expectation or prior knowledge
-our past experiences, prior knowledge, and expectations

Question 15

McGurk Effect

Answer 15

-The McGurk Effect is a phenomenon where what you see can change what you hear. It happens when the visual and auditory information don’t match, and your brain blends them together into something different. When the auditory component of one sound is paired with the visual component of another sound, it changes our perception of the sound

-E.g. If you watch a video of someone saying “Ga”, but the audio plays “Ba”, your brain might perceive it as “Da”—a mix of the two.
-Even though the actual sound is “Ba,” your brain relies on visual cues from lip movements and creates a new perception! This effect shows how vision and hearing work together in speech perception.

-top down processing and our expectations are overriding

Question 16

The Visual System: Light

Answer 16

-The stimulus: visible light
-Light is a form of electromagnetic energy that our eyes transduce into neural energy, allowing us to see.
-electromagnetic radation (waves of electromagnetic field)
-Light is made up of photons, which have wavelike properties as they travel through space.
-Different wavelengths of electromagnetic radiation classify light into various types (e.g., radio waves, gamma rays).
-Humans can only detect a small portion of the electromagnetic spectrum, known as the visible spectrum (750–390 nm).

Question 17

The Visual System: Light

How our eyes see color:
Wavelength Vs. Amplitude

Answer 17

Amplitude (wave height) → Perceived as intensity (brightness)
Higher amplitude = Brighter light
Lower amplitude = Dimmer light

Wavelength → Perceived as hue (colour)

Longer wavelength = Lower frequency (e.g., red)
Middle wavelength = Middle frequency (e.g. green)
Shorter wavelength = Higher frequency (e.g., blue)

Question 18

The Visual System: The Eye

Cornea

Answer 18

-focus

-where light first hits
-first job is focusing light
-helps bend light

Question 19

The Visual System: The Eye

Pupil

Answer 19

-amount of light

-can expand and contract to allow more light or less light into the eyes
-if we like or love what we see it expands

Question 20

The Visual System: The Eye

Lens

Answer 20

-more focus

-behind the pupil and bends light to hit the right part of the retina
-distance
-adjusts where light hits based on how far light is

Question 21

The Visual System: The Eye

Retina

Answer 21

Transduction

-back of the eye
-sensory receptors
-through optic nerves and out back to the brain

Question 22

The Visual System: The Eye

Brain

Answer 22

-Perception

Question 23

The Visual System: The Eye

First to End

Answer 23

1. Cornea (focus)
2. Pupil (amount of light)
3. Lens (more focus)
4. Retina (transduction)
5. Brain (perception)

Question 24

The Retina and Transduction

Answer 24

Retina contains photorecpetors (rods and cones) at the back of the eye that convert light into neural impulses

Photopigments in the photoreceptors change shape, affects the release of glutamate (sent to bipolar cells and ganglion cells)

Signal sent to adjacent bipolar cells (sensory neurons) and ganglion cells

Signal travels to the brain via optic nerve (blind spot)

Question 25

The Receptors Rods

Answer 25

-120 million cells (more than cones in 20:1 ratio) -high sensitivity -low acuity (sharpness) -primarily in the periphery (side eye) -black and white vision -low light conditions -do not respond to different wavelengths of light -only 1 kind of photopigment

Question 26

The Receptors Cones

Answer 26

-5 million cells -low sensitivity -high acuity (sharpness) -primarily in the fovea (center of retina) -color vision -most of what we perceive is sent to the cones -high light -needs more light to respond -3 types of photopigments (ability to perceive more light)

Question 27

Theories in Color Vision Trichromatic Theory

Answer 27

-3 kinds of cones -long wavelengths (red) -medium wavelengths (green) -short wavelengths (blue) -some people have fewer cones of a certain type -color blindness (dichromacy)

Question 28

Deuteranomaly

Answer 28

-less responsive to green colors -you do not perceive green -shortage of M cones

Question 29

Protanopia

Answer 29

-less responsive to red -you do not perceive red -shortage of L cones

Question 30

Tritanopia

Answer 30

-less responsive to blue -you do not perceive blue -shortage of S cones

Question 31

Theories of Color Vision Opponent Process Theory

Answer 31

-Bipolar cells combine inputs from different cones types and sends to ganglion cells -Ganglion cells respond in an antagonistic way to opposing pairs of wavelengths (activated by red but inhibited by green) -Also affects how we see vivid colors -Also explains why we cannot see some color combinations -Afterimages (due to adaptation)

Question 32

Visual Perception and the Brain left vs right hemisphere and light enters

Answer 32

Information from the left visual field is processed in the right hemisphere, and information from the right visual field is processed in the left hemisphere. This happens because the optic nerves cross at the optic chiasm, where signals from each eye’s visual field are sent to the opposite side of the brain -information from the left visual field goes to the right side of the brain and vice versa -regardless of the eye that sees it -information crosses sides at the optic chiasm -optic nerve first connects with the thalamus, then travels to V1 -primary visual cortex (occipital lobe that processes size, shape, color) -the brain processes features first and then sends information to the rest of the brain -cortical magnification -association cortex (process more complex perceptions of the brain, many locations of the brain)

Question 33

Visual Perception and the Brain Pathway of information through the brain to the Dorsal Visual Stream and Ventral Visual Stream)

Answer 33

-Retina, optic nerve, then to thalamus, then to V1 -then to either to Dorsal Visual Stream or the Ventral Visual Stream

Question 34

Visual Perception and the Brain (Dorsal Visual Stream and Ventral Visual Stream)

Answer 34

Dorsal Visual Stream: -from the occipital lobe to parietal lobe -Locate objects spatially; perform simple actions (head and eye movements, reaching) -identify spatial location of things, where an object is, and then create reflexive motor responses Ventral Visual Stream: -from the occipital lobe to temporal lobe -Recognize objects, conscious perception of details, attach meaning to what we see -meaningful perceptions (recognition, past memories, knowledge, memory)

Question 35

Blindsight

Answer 35

Some visual information bypasses V1 (primary visual cortex) and is processed through alternative pathways, like the superior colliculus, allowing for unconscious visual perception (e.g., in blindsight). Blindsight occurs when individuals with damage to the visual cortex can respond to visual stimuli without conscious awareness of seeing them. For example, a person with blindsight might reach for an object or detect movement even though they report being blind. This happens because other brain pathways, like those in the superior colliculus, still process some visual information outside of conscious awareness.

Question 36

Hollow Face Illusion

Answer 36

The Hollow Face Illusion occurs when a concave (hollow) mask appears as a normal convex (protruding) face due to top-down processing—our brain expects faces to stick out. However, motor actions (dorsal stream) are not tricked by the illusion. Studies show that while people consciously perceive the hollow face as normal, their hands can still accurately interact with it, demonstrating how the visual perception (ventral stream) and visual action (dorsal stream) function separately. Study: people can accurately flick off targets in the hollow face Visual action track (dorsal) isn't flooded by the illusion we experience through the visual perception track (ventral) Our hand knows what we do not consciously perceive!

Question 37

The Case of Dr. P

Answer 37

-Man who mistook his wife for a hat -musician who starts to have difficulty recognizing faces -tried to put wife's head on as a had -does not recognize any problem -he was smart, he could talk, and very talented musically (temporal lobe functions) -his primary visual cortex and temporal lobe works fine because he can see and hear -Diagnosis: Visual Agnosia (impairment in recognition of visually presented objects) -prosopagnosia: inability to recognize human faces -not due to a deficit in vision, language, or intelligence

Question 38

Visual Agonsia

Answer 38

impairment in recognition of visually presented objects

Question 39

prosopagnosia:

Answer 39

inability to recognize human faces

Question 40

The association cortex

Answer 40

-is the part of the cerebral cortex that integrates information from different sensory and motor areas to support higher cognitive functions like thinking, memory, and decision-making. -Unlike primary sensory or motor areas, it helps process complex stimuli, recognize patterns, and plan actions. -It is found in multiple brain regions, including the parietal, temporal, and frontal lobes. -Damage to the association cortex can lead to deficits in perception, attention, or problem-solving.

Question 41

Gastalt Psychology

Answer 41

How we group visual information to form perceptions The whole is greater than the sum of the parts -opposite of structuralism -5 theories account for most of visual illusions (proximity, similarity, continuity, closure, connectedness)

Question 42

Gastalt Psychology 5 theories account for most of visual illusions (describe how we naturally organize visual information) Proximity

Answer 42

Proximity: We group objects that are close together as belonging to the same group. (e.g., dots spaced closely appear as a single unit.)

Question 43

Gastalt Psychology 5 theories account for most of visual illusions (describe how we naturally organize visual information) Similarity

Answer 43

Similarity: We group objects that look alike. (e.g., rows of circles and squares are seen as separate patterns.)

Question 44

Gastalt Psychology 5 theories account for most of visual illusions (describe how we naturally organize visual information) Continuity

Answer 44

Continuity: We perceive smooth, continuous patterns rather than broken or jagged ones. (e.g., a wavy line crossing a straight line is seen as two separate lines, not small segments.)

Question 45

Gastalt Psychology 5 theories account for most of visual illusions (describe how we naturally organize visual information) Closure

Answer 45

Closure: We fill in gaps to perceive a complete, whole object. (e.g., a nearly complete circle with missing parts is still seen as a circle.)

Question 46

Connectedness Gastalt Psychology 5 theories account for most of visual illusions (describe how we naturally organize visual information)

Answer 46

Connectedness: Objects that are linked or touching are perceived as a single unit. (e.g., dots connected by lines are grouped together.)

Question 47

Depth Perception

Answer 47

Ability to see objects in 3 dimensions although the image that strikes the retina is two dimensional develops early in life (visual cliff) -Monocular cues: available to either eye alone -Binocular cues: result from seeing with both eyes

Question 48

Monocular cues vs. Binocular cues

Answer 48

Monocular cues: Depth cues that can be perceived with one eye alone. They help judge distance and depth in 2D images. Examples include relative size, interposition, linear perspective, texture gradient, and light and shadow. Binocular cues: Depth cues that require both eyes to work together. They help with perceiving depth more accurately by comparing the images from both eyes. Examples include retinal disparity (difference in images from each eye) and convergence (how much the eyes turn inward to focus on close objects).

Question 49

Monocular cue: Relative Size

Answer 49

Relative Size (Monocular Cue): When two objects are assumed to be the same size, the one that appears smaller on the retina is perceived as being farther away. This helps us judge distance by comparing the sizes of objects we are familiar with. For example, if two cars are parked on a road and one looks much smaller, we perceive it as being farther away, not actually smaller in size.

Question 50

Molecular Cue: Elevation (relative height)

Answer 50

Height in the Visual Field (Monocular Cue): Objects higher in the visual field appear farther away, while objects lower seem closer. However, above the horizon, the opposite happens—higher objects look closer than lower ones.

Question 51

Monocular cue: Interposition

Answer 51

Interposition: When one object blocks part of another, the blocked object looks farther away, and the one in front looks closer.

Question 52

Linear Perspective

Answer 52

Linear Perspective: Parallel lines appear to get closer together as they go farther away, eventually meeting at a vanishing point. The more they converge, the farther the distance looks.

Question 53

Relative Motion

Answer 53

Direction: Objects in front of the fixation point appear to move backward, while objects behind it seem to move forward. Speed: Closer objects move faster, while farther objects move slower.

Question 54

Binocular Cue: Retinal Disparity

Answer 54

Your eyes are spaced apart, so each one sees a slightly different view of the world. Your brain compares these two images to figure out how far away things are. Close objects → The difference between the two images is big (each eye sees the object from a noticeably different angle). Far objects → The difference is small (both eyes see almost the same image). This difference, or disparity, helps your brain create a sense of depth and perceive 3D space!

Question 55

Ames room

Answer 55

An Ames Room is a specially designed room that creates an optical illusion, making people appear much larger or smaller than they actually are. The room is distorted—one side is much farther away than the other, but it is designed to look like a normal rectangular room from a specific viewpoint. Because our brain assumes the room is regular, it misinterprets size differences, making one person seem tiny and another seem giant.