Introductory Psychology: Sensation
Ap psychology: Unit v Sensation Vision, hearing, smell, taste, touch, pain & body position
Similarities? Transduce stimulus energy into neural impulses More sensitive to change than to constant stimulation Provide us with information regarding our environment Differences? Each requires a different form of stimulus energy Each sends information to a different region of the brain for processing Sensation:Vision Part one Vision: The Stimulus Input
Light energy (electromagnetic energy) Two physical characteristics help to determine our sensory experience of light Wavelength The distance from one peak to another Determines HUE (color) Amplitude Height of each waves peak Determines INTENSITY (brightness) Shorter wavelength bluish colors Longer wavelength reddish colors
Great amplitude bright colors Small amplitude dull colors Vision: The Structure of the Eye
Cornea Location/Structure The clear bulge on thefront of the eyeball Function Protects the eye Bends light towards acentral focal point inorder to provide focus Vision: The Structure of the Eye
Pupil/Iris Location/Structure Adjustable opening in thecenter of the eye Surrounded by the iris (smallring of muscle tissue; color) Function Controls the amount of light that is able to enter the eye In bright conditions the iris expands, making the pupil smaller In dark conditions the iris contracts, making the pupil larger Vision: The Structure of the Eye
Lens Location/Structure A transparent structurethat is located behind thepupil Function Focuses image on the backof the eye (retina) Accommodation The process by which the eyes lens changes shape to help focus near or far objects on the retina Vision: The Structure of the Eye
Lens Problems Nearsightedness Also known as myopia Eyeball may be too long Image focused in front ofthe retina Farsightedness Also known as hyperopia Eyeball may be too short Image focused behind theretina Vision: The Structure of the Eye
Retina Location/Structure A multilayered, light-sensitive surface located at the back of the eyeball Function Contains cells that convert light energy into nerve impulses Includes three layers of cells Receptor cells (photoreceptors cones & rods) Bipolar cells Ganglion cells Vision: The Structure of the Eye
Cones Rods Number 6 million 120 million Location(in the retina) Center(fovea) Edge (periphery) Color sensitive Yes No Sensitivity in dim light? Low High Ability to detect sharp detail (acuity)? Photoreceptor Cells Vision: The Structure of the Eye
Bipolar Cells Receives message from the photoreceptors Transmits message to the ganglion cells, whichare then considered activated Ganglion Cells The axons of the ganglion cells converge to form theoptic nerve Light energy Rods & Cones Bipolar cells Ganglion cells Vision: The Structure of the Eye
Optic Nerve Location/Structure Nerve located at the backof the eyeball Function Sends visual information to the thalamus and thento the occipital lobes Where the optic nerve leaves the eye, there are no rods or cones, creating a blind spot Vision: Visual Processing
Feature Detectors Located in the visual cortex Nerve cells in the brain that respond to specific features Shape Angle Movement Vision: Visual Processing
Parallel Processing The processing of several aspects of a stimulus simultaneously The brain divides a visual scene into color, depth, form and movement Visual Information Processing
Feature Detection + Parallel Processing Color Motion Form Depth All processed separately but simultaneously Vision: Color Vision Young-Helmholtz Trichromatic Theory
(Hermann von Helmholtz & Thomas Young) The theory that the retina contains three different color receptors red, green and blue When stimulated in combination, these receptors can produce the perception of any color Color Blindness? Dichromatic Color Vision Individuals lack one of three receptors; usually the red or green receptor Vision: Color Vision Opponent-Process Theory of Color (Ewald Hering)
The theory that opposing retinal processes enable color vision Red-Green Yellow-Blue Black-White Light that stimulates one half of the pair inhibits the other half For example, some cells are stimulated by green and inhibited by red, while others are stimulated by red and inhibited by green Here's another example of creating an afterimage
Here's another example of creating an afterimage. Can you put the fish in the bowl? Try this. Stare at the yellow stripe in the middle of the fish in the picture below for about sec. Then move your gaze to the fish bowl. You should see a fish of a different color in the bowl. It helps if you keep your head still and blink once or twice after you move your eyes to the bowl. The afterimage will last about five seconds. Stare at the eye of the red parrot while you slowly count to 20, then immediately look at one spot in the empty birdcage. The faint, ghostly image of a blue-green bird should appear in the cage. Try the same thing with the green cardinal, and a faint magenta bird should appear. Sensation:Hearing Part two Hearing: The Stimulus Input
Sound energy Two physical characteristics help to determine our sensory experience of sound Wavelength/Frequency The distance from one peak to another Determines PITCH Amplitude Height of each waves peak Determines LOUDNESS Shorter wavelength high-pitch Longer wavelength low-pitch
Great amplitude loud sounds Small amplitude soft sounds Hearing: The Structure of the Ear
Outer Ear Relevant Structures Pinna Function Channels sound wavesthrough the auditory canal tothe eardrum (tympanicmembrane) Hearing: The Structure of the Ear
Middle Ear Relevant Structures (Eardrum) Hammer, Anvil, Stirrup Function Transmits the vibrations ofthe eardrum through apiston made of 3 tiny bones Hammer, anvil, stirrup These bones then transmitthe message to the cochlea Hearing: The Structure of the Ear
Inner Ear Relevant Structures Cochlea Basilar Membrane Function The incoming vibrations cause movement in the cochleas oval window, which then creates motion in the cochleas fluid This motion causes movement in the basilar membrane and its hair cells Eventually, the hair cells trigger an impulse in adjacent nerve fibers; converge to form the auditory nerve Hearing: The Structure of the Ear Hearing: Pitch Perception
Place Theory In hearing, the theory that links the pitch we hear with the place wherethe cochleas membrane is stimulated We hear different pitchesbecause different sound waves trigger activity at different places along the cochleas basilar membrane Best explains our perception of high-pitched sounds Hearing: Pitch Perception
Frequency Theory In hearing, the theorythat the rate of nerveimpulses traveling upthe auditory nerve matchesthe frequency of a tone, thus enabling us to sense its pitch Best explains our perception of low-pitched sounds Hearing: Sound Localization Hearing: Hearing Problems
Conduction Hearing Loss Caused by damage to the mechanical system that conducts sound waves to the cochlea Sound vibrations cannot be passed from the eardrum to the cochlea Example Punctured eardrum Sensorineural Hearing Loss Caused by damage to the cochleas receptor cells or to the auditory nerves Also called nerve deafness NERVE DEAFNESS CONDUCTION DEAFNESS Sensation: The Other Senses
Partthree Sensation: Olfaction (Chemical Sense)
TO DISCUSS General structure Chemical sense Gender differences Connection to limbic system Sensation: Gustation (Chemical Sense)
TO DISCUSS Crudest sense General structure Chemical sense Average adult? Lifespan? Supertasters Gender differences Instructions: Jelly Belly Activity
In partners, you will take turns eating Jelly Bellies Instructions for the EATER The eating partner MUST keep his or her eyes closed The eating partner MUST keep his or her nose plugged for the first few chews After 4-5 good chews, the eating partner should release his or her nose Instructions for the NON-EATER The non-eating partner should provide the eating partner with a Jelly Belly & silently note its flavor Sensation: Skin (Somesthetic Sense)
TO DISCUSS General structure Pressure? Other sensations? Sensation of pain Gate Control Theory Fast v. Slow Fibers Sensation: Kinesthetic (Somesthetic)
TO DISCUSS General structure Position & motion sensors Sensation: Vestibular (Somesthetic)
TO DISCUSS General structure Semicircular canals Otolith organs Planes of movement