Module 1.6b Sensation: Vision

Vocabulary and Key Concepts

• Wavelength: Distance between peaks of light waves, affecting color (hue).

• Hue: Dimension of color determined by wavelength.

• Intensity: Amount of energy in a light wave, related to brightness, determined by amplitude.

• Cornea: Protective outer layer of the eye.

• Pupil: Adjustable opening for light entry.

• Iris: Muscle controlling pupil size and color of the eye.

Learning Targets

• Characteristics of visible light and eye structures that focus it.

• Processing with rods and cones, pathway to the brain.

• Perception of color and function of feature detectors.

• Parallel processing in visual perception.

Light Energy and Eye Structures

• Visible light is part of electromagnetic spectrum.

• Cone receptors enable color detection under daylight, while rods enable peripheral and twilit vision.

Components of the Eye

• Lens: Focuses light on the retina.

• Retina: Contains rods and cones for light reception.

• Optic Nerve: Carries impulses to the brain.

• Blind Spot: Area without receptor cells where the optic nerve exits.

• Accommodation: Lens changes shape to focus on objects at varied distances.

Processing Visual Information

1. Light triggers chemical reactions in rods & cones.

2. Bipolar cells activate ganglion cells, forming optic nerve.

3. Information travels to thalamus, then to visual cortex.

Color Processing

• Trichromatic Theory: Three types of cones sensitive to red, green, blue.

• Opponent-Process Theory: Opposing cells process color perception (e.g., red-green).

• Phenomena like afterimages demonstrate color theory functions.

Feature Detectors

• Specialized nerve cells in the visual cortex respond to specific visual features.

• Supercell Clusters: Process complex patterns from basic feature detection.

Parallel Processing

• Brain processes multiple aspects of stimuli simultaneously, enabling quick recognition and integration.

• Key for strong visual experiences by relying on memory and visual information.