Gen Psy 200 Summer 2013 Sensation and Perception Part 1 (revised student)

Sensory Receptors and Transduction
Photoreceptors convert the light into neural activity by way of the Photopigments which break apart in the presence of light and change the membrane potential
Various forms of energy
Accessory structures Part of the sense organ that
modify the stimulus
Neural or sensory Physical structures or specialized cells receptors which detect and converts certain
Sensation and Perception Part 1 PSY 200 Summer 2013 Gary C. Forde
SENSATION AND PERCEPTION
Sensation: The process by which we receive , transform, and process sensory information into neural impulses (electrical impulse). • The brain uses these impulses to create experiences of vision, touch, hearing, taste, smell etc.
VISION
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Electro-magnetic radiation light waves - intensity and wavelength
Cornea, Pupil, Iris, Lens focus the light rays into Accessory a sharp image which is then projected onto the structures Retina
SENSATION
THE MAJOR SENSES
What is a sense?--- a system that translates outside information into neural activity
The basic process for all senses
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Conversion of light energy into a neural message takes place in the retina in specialized cells called photoreceptors. Two types of visual receptors 1. The rods are visual receptors that respond to brightness they are important for seeing in dim light. They are highly sensitive and covers our peripheral vision. 2. Cones- are visual receptors that allows detection of color as well as fine details of objects in bright light.
• Vision occurs when visual information is processed in the retina then travels through the bipolar neurons to the ganglion cells, to the optic nerve and on to the brain.
Perception: The process by which the brain interprets these sensations and turns them into meaningful representations of the world.
•
This involves cognitive processes, such as memory and thinkinl color televisions are based on the fact that normal human color vision is trichromatic Although we perceive the whole range of colors from a TV screen, it only has three colored phosphors (red, green, and blue) By varying the relative intensity of the three phosphors, we can fool the visual system into thinking it is seeing many different colors
Signal Detection: The theory that the threshold for detecting a signal
depends on: • The intensity of the stimulus • The level of background stimulation • The biological and psychological characteristics of the perceiver
FEATURE DETECTORS: GETTING DOWN TO BASICS
Neurons that respond to specific features of the visual stimulus such as horizontal or vertical lines Visual cortex compiles information from various cells to form meaningful patterns

Theories of Color Vision

Two primary theories of color vision
Trichromatic
theory Opponent-process theory
Trichromatic Theory of Color Vision
Trichromatic
BASIC PRINCIPLES OF SENSATION
What starts the process? a. The stimulation of specialized cells (sensory receptors) by some form of energy. b. Converting this energy into a neural signal so that it can be processed by the nervous system (transduction)
FIGURE 3.1: THE ELECTROMAGNETIC SPECTRUM
VISION Basic Component • Light : a form of energy (light waves or light rays) or Light: a form of energy known as electromagnetic rays which is undetected by the human eye. • What do we see or call vision? The visual stimulus we experience in vision are light waves. Light is a particle and a wave on the visual spectrum. Our eyes are only able to interpret a portion of the light spectrum.
IS SOMETHING ELSE THERE? IS THERE A DIFFERENCE BETWEEN STIMULI?
PRINCIPLES OF SENSATION
Sensory Adaptation: The process by which sensory receptors
become less sensitive to constant or unchanging stimuli. • May not occur when repeatedly exposed to certain strong stimuli.
Transduction

Light hits retina

Rods/cones generate neural signals Bipolar cells activated Ganglion cells activated



axons form optic nerve, takes message to brain
The Eye

Cornea


bends light protects

Pupil Iris

adjusts light

Lens

focuses images

Retina

receives info processes info
Converting Light into Images
OPPONENT-PROCESS THEORY