Sensation and Perception – Vision Focus

Vocabulary flashcards covering key terms from the lecture on sensation, perception, and the visual system.

Sensation

The process of detecting a stimulus in the environment; basic reception or detection.

Perception

The brain’s process of organizing and interpreting sensory input to give it meaning.

Mach Bands

Perceptual illusion in which adjacent shades appear lighter or darker at their borders, illustrating context effects in perception.

The Dress (2015)

Viral image demonstrating individual differences in color perception due to contextual and lighting cues.

Distal Stimulus

The physical object or energy in the environment that gives rise to sensory input.

Proximal Stimulus

The stimulus energy impinging on sensory receptors (e.g., retinal image).

Transduction

Conversion of physical energy (light, pressure, etc.) into neural impulses.

Neural Processing

Transmission and manipulation of electrical signals within the nervous system.

Recognition

Identifying a perceived stimulus and assigning it meaning.

Action (in perception)

Behavioral response driven by perception, such as moving or grasping.

Electromagnetic Energy

Form of energy light belongs to, characterized by varying wavelengths.

Wavelength

Distance between successive peaks of a wave; determines perceived color in vision.

Visible Light Range

Portion of the electromagnetic spectrum from roughly 380–760 nanometers.

Cornea

Transparent front surface of the eye that begins focusing light.

Pupil

Adjustable opening through which light enters the eye.

Lens

Transparent structure that further focuses light onto the retina.

Retina

Light-sensitive layer at the back of the eye containing photoreceptors.

Fovea

Central retinal region with highest cone density and visual acuity.

Optic Nerve

Bundle of ganglion-cell axons that carries visual information to the brain.

Rods

Photoreceptors sensitive to light intensity; enable vision in dim light, not color.

Cones

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

Foveal Vision

Vision mediated by cones in the fovea—high acuity and color detail.

Peripheral Vision

Vision outside the fovea, dominated by rods—high sensitivity, low detail.

Convergence (Retina)

Ratio of photoreceptors to ganglion cells; high convergence → more sensitivity, less resolution.

Sensitivity (Vision)

Ability to detect faint stimuli; enhanced by rod convergence.

Resolution (Vision)

Ability to discern fine spatial detail; greatest in low-convergence cone pathways.

Typical Visual Pathway

Retina → Bipolar cells → Ganglion cells → Optic nerve → LGN (thalamus) → Primary visual cortex → Secondary areas.

Ventral Stream (Temporal Pathway)

"What" pathway for object identification; projects to inferior temporal cortex.

Dorsal Stream (Parietal Pathway)

"Where" or "How" pathway for spatial location and motion; projects to posterior parietal cortex.

Prosopagnosia

Face blindness caused by damage to the fusiform gyrus in the ventral stream.

Akinetopsia

Motion blindness resulting from damage to area V5/MT in the dorsal stream.