PSYC 4140_Class 11_Vision

Types of Neurons

• Sensory Neurons

  • Bring in incoming information from the Peripheral Nervous System (PNS)

  • Responsible for input signals to the Central Nervous System (CNS)

• Interneurons

  • Connect and process information within the CNS

  • Responsible for integration of signals

• Motor Neurons

  • Attach to muscle fibers in the PNS

  • Responsible for output signals

Structure of the Visual System

• Components of the visual pathway:

  • Optic Nerve

  • Optic Chiasm

  • Optic Radiation

  • Lateral Geniculate Nucleus

  • Optic Tract

  • Primary Visual Cortex

Vision and Visual Perception

• Outline of Vision

  • Vision as a stimulus

  • Vision as a receiver

  • Visual perception

• Mistake Identification Activity

  • Visual details:

    1. 1 2 3 4 5 6 7 8 9

    2. IT'S LIT

Sensory Processes

• General Sensory Process

  • Matter or Energy influencing the body

  • Chemical/Electrical Activity within the body

  • Subjective sensation as a psychological experience

  • Physical stimulus leading to physiological response

  • Resulting sensory experience

Light and Photoreception

• Light

  • Small portion of the electromagnetic spectrum

  • Eyes as LED screens in reverse that receive light energy

  • Photoreceptors receive light, creating environmental awareness

  • Importance of light for developing detection systems

Properties of Light

• Electromagnetic Spectrum

  • Includes Radio Waves, Infrared, Visible Spectrum, X-rays, and Gamma Rays

  • Wavelengths define light properties and range from 0.01 nm to 700 nm

Specific Properties of Light

• Light is perceived through various wavelengths as different colors

  • Emit or reflect light to become visible to humans

• Other Species' Experiences with Light

  • Sensitivity to wavelengths invisible to humans influences their environmental experience, e.g. bees seeing UV light

• Light as Particles

  • Photons are light particles affecting brightness perception

  • Interaction of photons leads to absorption, reflection, and refraction creating visual perception

Optic Array

• The concept of the optic array:

  • Comprises all light interactions with the environment, influencing perception

  • Changes constantly both spatially and temporally

Human Visual Adaptation

• Humans are sensitive to a small portion of the electromagnetic spectrum

• Adaptations exist for various environments (e.g., low-light for cats)

Eye Structure for Light Focus

• Key Structures:

  • Iris, lens, cornea, ciliary body, vitreous body, pupil, conjunctiva, anterior chamber, choroid, retina, macula, optic nerve

• Focusing Light

  • Light waves enter through the cornea, passing through the lens adjusted by ciliary muscles

Photoreceptors in the Eye

• Two types:

  • Rods

    • Night vision (scotopic)

    • Approximately 120 million per eye

    • Sensitive to low light; not color sensitive; located primarily in periphery

  • Cones

    • Day vision (photopic)

    • Approximately 6 million per eye

    • Sensitive to color and function best in bright light

Pathways of Visual Information

• Through Pathway:

  • Involves photoreceptors, bipolar cells, and ganglion cells in signal transmission

• Lateral Pathway:

  • Involves horizontal and amacrine cells sharing information across the retina

Visual Field and Color Perception

• Color Vision Theories:

  • Trichromatic Theory: Based on three primary colors

  • Opponent Process Theory: Excitation and inhibition of certain wavelengths creating color perceived oppositions

Contrast Detection

• Receptive fields allow group information from multiple rectangles, enhancing local contrast perception to promote visual detail

Final Thoughts on Visual Processing

• Visual information processing involves complex pathways and structures in the eye leading to interpretations at the brain level.