Absolute threshold: The smallest amount of something we can sense.

Transduction: Changing something, like light or sound, into a signal our brain understands.

Just noticeable difference: The smallest change in something we can notice.

Sensory adaptation: Getting used to a constant sensation, like a smell or a sound.

Weber’s law: The idea that noticing a change depends on how big it is compared to what’s there.

Synesthesia: When senses blend, like seeing colors when hearing sounds.

Retina: The back part of the eye that detects light.

Blind spot: A part of the eye where we can't see because there are no detectors there.

Visual (optic) nerve: The nerve that sends visual information from the eye to the brain.

Photoreceptors: Cells in the eye that respond to light.

Rods: Photoreceptors that help us see in dim light and detect movement.

Lens: The part of the eye that focuses light to make images clearer.

Accommodation: The lens changing shape to focus on close or far objects.

Nearsightedness: When you can see things up close but not far away.

Farsightedness: When you can see things far away but not close up.

Trichromatic theory: The idea that we see color through three types of color detectors (red, green, and blue).

Opponent-process theory: The idea that we see colors as pairs (like red-green, blue-yellow).

Fovea: The part of the retina where we see most clearly.

Cones: Photoreceptors that help us see color and detail in bright light.

Ganglion cells: Cells in the eye that send visual information to the brain.

Dichromatism: Color blindness where two color detectors work instead of three.

Monochromatism: Total color blindness, seeing only in shades of gray.

Prosopagnosia: Difficulty recognizing faces.

Blindsight: Being able to respond to visual information without consciously seeing it.

Place theory: A theory that we hear pitch based on where sound waves hit in the inner ear.

Volley theory: The idea that groups of nerve cells work together to send sound signals for higher pitches.

Frequency theory: The idea that we hear pitch based on how fast nerves send signals.

Conduction deafness: Hearing loss due to problems with parts that carry sound to the inner ear.

Sensorineural deafness: Hearing loss due to problems in the inner ear or the nerve that connects it to the brain.

Pheromones: Chemicals animals release to communicate with others.

Gustation: The sense of taste.

Olfaction: The sense of smell.

Gate control theory: The idea that our spinal cord can block pain signals or let them through.

Phantom limb syndrome: Feeling sensations in a limb that has been removed.

Vestibular sense: Our sense of balance and body position.

Semicircular canals: Parts of the inner ear that help us balance.

Kinesthesis: Our sense of where our body parts are and how they move.

Top-down processing: Using what we already know to make sense of information.

Bottom-up processing: Starting with details to understand the whole picture.

Perceptual sets: Expectations that shape how we perceive things.

Gestalt psychology: The idea that we see things as whole forms, not just parts.

Figure/ground: Distinguishing a shape from its background.

Selective attention: Focusing on one thing and ignoring others.

Cocktail party effect: Focusing on one voice among many.

Inattentional blindness: Missing something in plain sight because you're focused elsewhere.

Change blindness: Not noticing changes in a scene when you're focused elsewhere.

Binocular depth cues: Clues about depth that require both eyes.

Monocular depth cues: Clues about depth that can be seen with one eye.

Retinal disparity: The slight difference between what each eye sees, which helps us see depth.

Interposition: When one object blocks another, we see it as closer.

Linear perspective: When parallel lines appear to meet in the distance, helping us perceive depth