Sensation and Perception

Sensation

When your senses (eyes, ears, skin, nose, tongue) take in information from the world.

Perception

How your brain interprets the sensory info.

Bottom Up Processing

When you start with the sensory input and build up to understanding.

Top down Processing

When you use your knowledge, expectations, or experience to interpret what you sense.

Prosopagnosia

“Face blindness” — when someone can see faces but can’t recognize who they belong to.

Selective Attention

You can only fully focus on one thing at a time — your brain picks what to pay attention to.

Cocktail Party

You’re at a noisy party, tons of voices around… but if someone says your name, you suddenly hear it.

In-attentional Blindness  

When you don’t see something obvious because you’re focused on something else.

Change Blindess

When you don’t notice a change because it happens slowly or your focus shifts.

Sensory Threshold

The minimum level of a stimulus (sound, smell, light, etc.) needed for you to notice it.

Absloute Threshold

The smallest amount of something you can detect 50% of the time.

Priming

When you’re unconsciously prepared to think or react a certain way because of something you saw or heard before.

Difference Threshold

The smallest change you can notice between two things.

Weber’s Law

Says that the change you can notice depends on the percentage, not the amount.

Sensory Adaption

When you get used to a constant stimulus and stop noticing it.

Transduction

When your senses change energy into brain signals.

Electromagnetic Spectrum

All the types of light waves (energy waves).

Cornea

The clear outer layer of your eye that bends light to help focus it.

Pupil

The black hole in the middle of your eye — it lets light in.

iris 

• The colored part of your eye (blue, green, brown).

• It controls the pupil — makes it bigger or smaller.

lens

The clear part behind the pupil that focuses light onto the retina.

Accomodation

When the lens changes shape to focus on things at different distances.

Retina

• The back of your eye where light hits and gets turned into neural signals.

• Contains rods (for dim light) and cones (for color and detail).

Acuity 

How sharp or clear your vision is.

Nearsighted (Myopia)

You can see close objects clearly but far objects are blurry.

Farsighted (Hyperopia)

You can see far objects clearly but close ones are blurry.

Rods

• Help you see in the dark (dim light).

• Only see black, white, and gray — no color.

• Located around the edges of your retina.

Cones 

• Help you see color and detail in bright light.

• Mostly in the fovea (center of your retina).

Bipolar Cells

They are the middle messengers — they take signals from rods and cones and pass them on to the ganglion cells.

Ganglion Cells

• Get information from bipolar cells and send it to the brain through their axons.

• All their axons bundle together to make the optic nerve.

Optic Nerve 

• The pathway that carries visual messages from your eye to your brain.

• There’s a blind spot where the optic nerve leaves the eye — no rods or cones there.
  👉 Think: “Cable from eye → brain.”

Foeva

• The center of the retina, where cones are packed tightly.

• Gives you your clearest, sharpest vision.

Trichromatic (Three-Color) Theory

• Says we have 3 types of cones that see:

  • 🔴 Red

  • 🟢 Green

  • 🔵 Blue

• All the colors we see are made by combining these three.

Color-Deficient Vision (Color Blindness)

When someone lacks one or more cone types (red, green, or blue).

• They can still see color, just not all of them clearly.

Opponent-Process Theory

• Says color vision works in opposite pairs:

  • 🔴 Red ↔ Green

  • 🔵 Blue ↔ Yellow

  • ⚫ Black ↔ White

• When one color in a pair is active, t

Afterimage Effect

When you stare at one color for a while, then look away and see its opposite color.

Sound Waves

• Vibrations that travel through air (or another medium) to your ears.

Amplitude 

• How tall the sound wave is = loudness.

Frequency

How fast the sound waves vibrate.

Pitch

How high or low a sound is.

Outer/External Ear

The part you can see — collects sound and sends it into the ear.

Eardrum 

A thin skin that vibrates when sound hits it.

Middle Ear

Has three tiny bones (hammer, anvil, stirrup) that make the vibrations stronger.

Cochlea

A snail-shaped part filled with fluid that turns sound vibrations into signals.

Inner Ear

The deep part of your ear that helps with hearing and balance.

Basilar Membrane 

Inside the cochlea — moves tiny hair cells that change sound into brain signals.

Audoitry Nerve

The wire that carries sound messages from your ear to your brain.

Audiotory Cortex

The part of your brain that understands sounds (like words or music).

Place Theory

Different pitches (high or low sounds) are heard because different spots on the cochlea’s basilar membrane vibrate.

Volley Theory 

For medium pitches, groups of hair cells take turns firing so your brain hears higher frequencies.

Audiotory Locaization

Your brain figures out where a sound comes from by comparing which ear hears it first and loudest.

Conduction Hearing Loss

When sound can’t get through the outer or middle ear (like earwax or damaged bones).

Sensorineirl Hearing Loss

When hair cells or the auditory nerve in the inner ear are damaged.

Cutaneous Receptor 

The skin sensors that detect touch, pressure, pain, and temperature.

Kinestheisis

Your sense of body position and movement — helps you know where your limbs are without looking.

Vestibular Senses

Your sense of balance and body movement — helps you know if you’re upright, spinning, or tilting.

Semiciruclar Canals

Three fluid-filled loops in your inner ear that help with balance and sensing movement.

Pain

Your body’s warning signal that something is wrong or being damaged.

Gate Control Theory

Says there’s a “gate” in your spinal cord that either blocks or lets pain signals through to the brain.

Phantom Limb

When people who lost a limb still feel sensations or pain where it used to be.

Sensory Interaction

When your senses work together and affect each other.

Gustaotry System 

Your sense of taste — includes your tongue, taste buds, and parts of your brain that process flavor.

Taste Receptors

The taste buds on your tongue that detect sweet, sour, salty, bitter, and umami (savory).

Unami

A savory or meaty taste (like in soy sauce, cheese, or meat).

Olfaction

Your sense of smell.

Odor Molecules 

Tiny chemical particles in the air that your nose picks up to smell things.

Papiale

The tiny bumps on your tongue that hold your taste buds.

taste Buds

The receptors for taste inside your papillae — they send signals to your brain.

McGurks Effect

When what you see affects what you hear.

Supertasters 

People with extra taste buds — flavors feel very strong (they might hate bitter foods).

Nontasters

People with fewer taste buds — flavors seem weaker or bland to them.

Cillia

Tiny hair-like cells in your nose that detect smell molecules and send signals to your brain.

Ofacotry Bulb

The brain part that receives smell info from the nose and helps you recognize different scents.

Gesalt 

Means “whole.” Your brain likes to see patterns and complete pictures, not just random parts.

Figure Ground

You focus on one part (the figure) and everything else becomes the background (ground).

Clsoure

Your brain fills in missing pieces to make a complete image.

Depth Percetion

Your ability to see things in 3D and know how far away they are.

Bionoular Cues

Depth cues that need both eyes.

Retinal Disparoty

Each eye sees a slightly different image, and your brain combines them to tell how far something is.

Convergence

Your eyes turn inward when looking at something close.

Monocular Cues

Depth cues that work with one eye — help you judge farther distances.

Reative Size 

If two objects are the same size, the one that looks smaller is farther away.

Interposotion

If one object blocks another, the one doing the blocking looks closer.

Linear Persecptive

Parallel lines (like train tracks) seem to meet as they go into the distance — shows depth and distance.

Apparent Movement

When something looks like it’s moving but it’s not.

Stroop Effect 

When your brain gets confused because words and colors don’t match.

Pereptual Adaption

Your brain’s ability to adjust to changed visual input.

Percetual Set

Your expectations affect what you see or notice.

Context Effects

The situation or surroundings change how you interpret something.