bio psych: seeing, perceiving, and sensing the world

What is sensation?

The registration of physical stimuli from the environment by sensory organs.

What is perception?

The brain’s subjective interpretation of sensory information.

What are sensory receptors?

Specialized cells that transduce physical energy into neural activity.

What is a receptive field?

The region of sensory space where a stimulus changes a receptor’s activity.

Why does receptor density matter?

Higher receptor density increases sensitivity in that area.

What are neural relays?

Sequences of neurons that transmit and modify sensory information to the cortex.

What is a topographic map?

A spatial neural representation of the body or sensory world in the brain.

What range of light can humans see?

About 400 nm (violet) to 700 nm (red).

What is the retina?

The light-sensitive surface at the back of the eye that converts light into neural signals.

What is the fovea?

A central retinal region with dense photoreceptors responsible for highest visual acuity.

What causes the blind spot?

The optic disc where the optic nerve exits the eye and no photoreceptors exist.

What are rods?

Photoreceptors sensitive to low light used for night vision.

What are cones?

Photoreceptors responsible for color vision and high visual acuity in bright light.

What are the three cone pigment sensitivities?

Blue (~419 nm), green (~531 nm), and red (~559 nm).

What retinal cells form the optic nerve?

Retinal ganglion cells.

What is the optic chiasm?

The point where optic nerves partially cross before entering the brain.

What happens at the optic chiasm?

Nasal retinal fibers cross so left visual field goes to the right brain and vice versa.

What is the dorsal visual stream?

The “how” pathway from occipital to parietal cortex guiding actions toward objects.

What is the ventral visual stream?

The “what” pathway from occipital to temporal cortex identifying objects.

What do retinal ganglion cells detect?

The presence or absence of light, not shape.

What is luminance contrast?

The difference in light intensity between an object and its surroundings.

What do neurons in V1 detect?

Orientation of lines or bars of light.

What is trichromatic theory?

Color vision based on three cone types detecting red, green, and blue wavelengths.

What is opponent-process theory?

Color perception based on opposing pairs such as red–green and blue–yellow.