Final Exam Review Notes

Final Exam Details

Final exam will be online through Canvas.
Duration: Two hours.
Availability: From Tuesday, May 13 at 12:30 PM to Wednesday at 12:30 PM (24-hour period).
Format: Approximately 45 multiple-choice questions and a section of short answer questions.
Total points: 100.

Sensation and Perception

Distal Stimulus: The actual object in the world. We cannot experience this directly.
Proximal Stimulus: The information we collect from the world (e.g., light image on the back of the eye).
Sensation: How we collect proximal information from the world.
- Example: How light hitting the back of our eye is turned into neuron firing.
- Can be studied by examining sensory organs (e.g., eyeball, inner ear).
Perception: How we interpret the information collected, adding guesses and assumptions to get a conscious experience.
- Requires the brain to study.

Measuring Perception

Difficult to measure directly.
Thresholds:
- Absolute Threshold: Minimum amount of stimulus needed to notice it.
- Difference Threshold: Minimum difference between two stimuli needed to notice a difference.
Methods to Measure Thresholds:
- Method of Limits: Gradually increasing or decreasing intensity.
  - Example: Eye doctor using a chart to make it gradually harder to read (descending limits).
  - Bias: Expectations or habits can influence responses.
- Method of Adjustment: Allowing people to adjust the stimulus themselves.
  - Quick but imprecise.
- Method of Constant Stimuli: Randomly presenting different intensities many times.
  - Time-consuming and expensive but very precise.
  - Example: Hearing tests.

Weber's Law

Thresholds can change based on the initial intensity of the stimulus.
As intensity increases, a bigger change is needed to notice a difference.
Example: Easier to tell the difference between 1 and 2 pounds than 50 and 51 pounds.
$\frac{\Delta I}{I} = k$ , where $\Delta I$ is the just noticeable difference (JND), $I$ is the intensity of the stimulus and $k$ is a constant.
Related to the decibel scale for loudness.
- Larger changes in sound are needed to notice a change as things get louder.
- There's a bigger difference between 100 and 120 decibels than between 20 and 40 decibels.

Magnitude Estimation

Estimates how intense something feels rather than measuring threshold.
Example: Judging the brightness of candles relative to each other.
Brightness: As intensity increases in the real world, it doesn't feel as much brighter.
Electric shock: Small changes in the real world can feel like larger changes due to pain.
Length: Two feet feels twice as long as one foot.

Cornea and Lens

Focusing light onto the back of the eye.
Cornea: Starts bringing scattered light back together.
Lens: Helps with accommodation (focusing light more or less depending on distance).
- Far away: Less focusing needed.
- Close-up: More focusing needed, leading to headaches and eye strain.

Related Issues

Presbyopia: Lens doesn't work as well with age, making it hard to focus on close-up objects.
Myopia (Nearsightedness): Can see things close-up but not far away; focusing light too much.
Hyperopia (Farsightedness): Can see things far away but not close-up; not focusing light enough.
Astigmatism: Focusing light differently in different dimensions (vertically vs. horizontally), leading to blurry images.

Foveal Region vs. Periphery

Fovea (Center): Mainly cones.
Periphery (Surrounding Area): Rods.
Rods: Sensitive to light; used when trying to see in low light.
Cones: Midget bipolar cells with small receptive fields.
Small Receptive Fields:
- Better acuity (precision).
- Low light sensitivity.
Large Receptive Fields:
- More sensitive to light.
- Lower acuity.
Cannot read out of the edges of your vision.

Photoreceptors

Photoreceptors contain discs with pigment made of retinal and opsin.
Photons of light hit retinal, changing its shape and causing a photoreceptor to fire.
Different cone types and rods have different types of opsin.
- Makes them sensitive to different wavelengths of light.
- Results in short, medium, and long wavelength photoreceptors.

Pigment Leeching and Regeneration

After detecting light, it takes time for photoreceptors to regenerate.
Leads to dark adaptation: Initially hard to see in the dark, but it gets easier with time.

Receptive Fields

Larger ones: More sensitive to light but less precision.
Smaller ones: More precision but less sensitivity to light.
If light hits the center of the receptive field, it makes the bipolar cell fire more.
If it hits the surrounding area, it fires less (lateral inhibition).
Bipolar cells detect edges where there's a different amount of light in one area versus the area next to it.

Visual Experiences

Scotopic: Black and white vision at nighttime (rods only).
Photopic: Normal lighting conditions using cones.
Mesotopic: Twilight conditions using both rods and cones.
- Blues appear brighter because rods see short wavelengths, and cones see short as blue.

Light Adaptation

Under normal lighting conditions, most cones and all rods are bleached.
In the dark, they regenerate over time, improving vision.

Brain Pathways

Everything in the right visual field gets caught by the left side of both eyes and vice versa.
Lateral Geniculate Nucleus (LGN): First stop in the brain for organizing information.
Visual Cortex: Receives information from LGN.

Visual Cortex Feature Detectors

Simple cortical cells: detect lines of certain orientation.
Complex cortical cells: detect lines of certain orientation moving.
End-stopped cortical cells: detect lines of certain orientation moving of a certain length.
Hypercolumn: Different locations in the visual cortex for different locations on your retina (retinotopic map).

Evidence on How we know These Exist

Cell Recording: Measure the feature detectors themselves to see how active they are while looking at stuff
Selective Adaptation: Stare at a feature for a little while, you will tire it out. When you try to detect it again, you'll be worse at it
Selective Rearing: If you've never experienced a feature, you won't develop feature detectors for it, so you won't be able to detect it

Object Perception

Making sense of lines and edges to perceive objects.
Inverse Projection Problem: Three-dimensional world being projected into a two-dimensional image on the back of the eye.
- Leads to loss of depth information.

Gestalt Principles

Simplicity: See things as simply as possible.
Similarity: Group similar features together.
Continuation: Group things to form nice straight lines or smoothly curved lines.
Proximity: Group features that are close together in space.
Common Region: Group features together that are in the same shared border.
Meaningfulness: Group things into meaningful objects like faces.
Uniform Connectedness: Group features that are physically connected together.
Synchrony: Group things that are changing at the same time together.
Common Fate: Group things that are moving in the same direction.

Recognition by Components Theory

Identifying objects from different viewpoints by recognizing their basic three-dimensional parts (geons).
Objects are filled out of Lego parts.
Each geon has unique features from many different viewpoints (e.g., cylinder has two parallel lines).

Attention

Inattentional Blindness: If you're not paying attention to something, it's like you're blind to it.
Change Blindness: If you're not paying attention to something, you won't notice the change.
We process different features from the world in different areas of our brain (color, shape movement distance and so on all in different locations)
How do you know what goes and what?
- Bind features together based on attention.

Motion

Real Motion: Real things moving in the world.
Motion Aftereffects: Staring at motion for a while, then seeing motion in the opposite direction when looking away (related to selective adaptation).

Illusory Motion

Apparent Motion: Motion between two stationary objects where one appears and disappears, and then the same thing appears somewhere else.
- Also called the phi phenomenon.
- Example: TV and movies using still frames.
Another Type Of That: Motion within a single stationary object (e.g., snakes twisting).
- Seems to happen if there's areas of high contrast, very bright areas next to very dark areas.
Induced Motion: Motion in one thing causes you to see motion in another.
- Example: Background moving in Super Mario making the character feel like they're moving forward.
Implied Motion: Still picture showing something in action, activating motion areas of the brain.

Corollary Discharge Theory

When trying to figure out whether something's moving or not, consider whether something moved on your eye and whether you move your eye.
The brains tells/compares both these things to see if you should see motion.
Everything moves on your eyes just because your eyes moved.

Aperture Problem

If you're looking through a hole at part of an object, you can't tell how it's actually moving.
Solve the aperture problem by seeing the edges of things; use end-stopped cortical cells to detect edges moving.

Color Mixing

Additive Color Mixing:
- Colors seen based on light being shined into your eye.
- Start with no light, then add short, medium, or long wavelengths.
Subtractive Color Mixing:
- Color of objects based on what they absorb or take away from the world.
- Start with all wavelengths of light.
- Objects subtract out or keep some wavelengths, and the rest bounce off. When doing this you will be adding a color into the enviornment.

Trichromatic Theory

Color seen is based on the pattern across all three types of photoreceptors (short, medium, and long cones).
Can make different patterns across your three cones by differing the intensity, and get different color.
If all three cones are active at the same time, you see white.

Color Constancy

Objects look the same under different types of lighting conditions.
Mechanisms:
- Chromatic Adaptation: Become less sensitive to a particular wavelength of light.
- Effect of Surroundings: Brain looks at the surrounding area to calculate what type of lighting is hitting an object and adjusts for that.
- Effect of Memory: Remembering the color of an object (e.g., knowing you're wearing a white T-shirt).

Depth Perception

Ocular Motor Cues:
- Rely on the muscles of your eye.
- Convergence: How much your eyes turn inward to focus on an object.
- Accommodation: How much you're squeezing your lens to focus light.
Pictorial Cues:
- What we see that relies on pictures or images
- Occlusion: If one thing's blocking another, the blocking thing must be closer.
- Relative Height: Things touching the ground higher up in an image are farther away.
- Relative Size: Things that should be the same size appear smaller when farther away.
- Perspective Convergence: Lines converge in the distance.
- Familiar Size: If you know something is big and it looks small, it must be far away.
- Atmospheric Perspective: Things look blue and fuzzy when they're far away.
- Texture Gradient: Things close to you are evenly spaced out; things farther away are more packed together.
- Shadows can tell you something about where something is. Motion Parallax:
  - Where how things cross your eye tells you how far something is
  - Someone moves accross you eye fast it's close. If it's far away it slower. Gives you sense of depth

Binocular Depth Information

Binocular Disparity: The image for an object with not be on the same location in both eye
The Haropter: Imaginary line of dots.
- This is how you measure binocular disparity
It tells you if thing's closer or further away

Absolute Disparity

How much does it not match in front of both eyes?
For The Brain
You're looking at something. Anything that is at the same location to you is the distance you are looking. Anything that's too far out is closer, anything too far in is further distance.

Relative Disparity

Compares absolute disparity from one thing to another.
Allows you to see the same distances between things regardless of what you're looking at.

Size Perception

Based on how big something is on your eye and how far away it is from you.
Size Distance Scaling Equation: $s = r \times d$ (Size equals retinal size times distance).
Example:
*Ames Room, person looks big bc far side closer

Sound

Pressure waves in the air (alternating areas of high and low pressure).
Frequency: How many cycles of pressure changes happen per second (Hertz).
- Range of hearing: 20 to 20,000 Hz.
- Related to pitch (high frequency = high pitch, low frequency = low pitch).
Amplitude: How big of a difference there is between the high and low pressure areas.
The bigger the amount larger the amplitude the more quite. Bigger smaller big.
Measured in decibels (every 20 decibels is 10 times bigger in amplitude).

Decibels Math

You can't see AI

Use a blank sheet!

Every 20 decibles 10x

Ex: How many decibals is a thershoild amount. So it will be zero!
Then it's 60 decible what amount would that be, go up 20 incrmenets will be 1000x total!

Also known is tambor which is a grab bag on how we actually here things
Remember to only have how the frq and then amp afffects. Other way around.
*One last time frequency high pitch. Frq.

Harmonics

All sound in the real world is made out of many frequencies combined together.
Combined wave frequency is determined by the lowest frequency.
Multiples of that lowest and higher up frequencies will result to be its multiples.
*What's the 10th harmonic= take frequency * the amount you want for harmonic