Sensation 2 4 Sensation the activation of receptors in the various sense organs eyes ears nose skin and taste buds Sensory receptor specialized form of neurons the cells that make up the nervous system Transduction conversion of outside stimuli into a neural signal in the brain Sensory Thresholds Subliminal Sensation Just noticeable differences jnd or the difference threshold the smallest difference between 2 stimuli that is detectable 50 of the time Absolute Threshold the smallest amount of energy needed for a person to consciously detect a stimulus 50 of the time Subliminal Stimuli stimuli that are below the level of conscious awareness Just strong enough to activate the sensory receptors but not strong enough for people to be consciously aware of them Subliminal Stimuli in Advertising Research suggests that subliminal perception does not work in advertising Supraliminal Stimuli things you can be consciously aware of but because your attention is elsewhere you are not Habitution and Sensory Adaptation Habituation the tendency of the brain to stop attending constant unchanging information Sensory Adaptation the tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging cid 127 Microsaccades constant movement in the eyes even when staring at something your eyes are never actually still Sight Eyes contain the sense receptors for sight The energy these receptors respond to is light Light contains the properties of both wave and particles Three things that are key to our perceptions of light determined by the amplitude of the wave how high or how low the actul wave is Brightness Hue Saturation Brightness Hue color determined by the length of the wave found at the blue end Saturation refers to the purity of the color people see mixing in black or gray would lessen the saturation long wavelengths are found at the red end of the visible spectrum portion of the spectrum visible to the human eye whereas shorter wavelengths are How light works in relation to the eye light enters eye throuh cornea and pupil iris controls the size of pupil from the pupil liht passes through the lens to the retina in the retina liht is transformed into nerve impulses nerve impulses travel to brain Structure of the Eye Retina final stop for light in the eye Contains three layers ganglion cells bipolar cells Photoreceptors photoreceptors that respond to various light waves cones travel to the brain Visual Disorders Rods adapted for vision in dim life cannot see color This is why color is not visible at night Cones adapted for color vision daytime vision and detailed vision Requires a lot of light Give very precise and very clear vision Fovea helps you to be able to see whats in a certin spot because it has a lot of cones Light passes through ganglion and bipolar cells until it reaches and stimulates the rods and cones Nerve impulses from rods and cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 Presbyobia develops as we age decreased flexibility of the lens and therefore inability to focus on nearby objects Deficits within the lens Cataract the lens becomes completely cloudy Deficits due to the shape of the eye cid 127 Myopia can focus well on nearby objects but not on distant objects Eyeballs are elongated Hyperopia can focus on distant objects but not on nearby objects Eyeballs are flattened Astigmatism means your eye isnt round Not flat or elongated just irregulary curved A lot harder to correct than near or far sightedness cid 127 Glaucoma increased pressure in the eyeball which can lead to optic nerve damage and the loss of peripheral vision tunnel vision Trichromatic vision theory of color vision that proposes three types of cones red blue and green Afterimages when a visual sensation persists for a brief period of time even after the original stimulus is removed cid 127 Opponent process theory we percieve color not in terms of independent colors but in terms of a system of paired opposites cid 127 Monochrome colorblindness a person s eyes either have no Red green colorblindness either the red or green cones are not working Protanopia red cones Deuteranopis green cones Tritnopia blue cones are not working Sex linked inheritance females have to have colorblindness on both genes where males only have to have it on one gene making colorblindness more common in males Sound waves vibrations of molecules in the air or another medium this is why there is no sound in space or vacuums Purity interpreted as timbre a richness in the tone of the sound what allows us to distinguish our mothers voice from our sisters Humans have limited range 20Hz 20 000Hz with the greatest sensitivity from about 2 000Hz 4 000Hz cid 127 Wavelength interpreted as frequency or pitch high medium or low Amplitude interpreted as volume how soft or loud a sound is Measuring Sound Waves Hertz Hz cycles or waves per second measurement of frequency Decibels dB unit of measurement for loudness 15dB normal person preathing 30dB library 70dB vacuum cleaner 85 90dB prolonged exposure to this sound can damage hearing 100dB chainsaw 135dB headphones turned to highest volume Color Vision red versus green yellow versus blue white versus black Color Blindness Sensation of Hearing Sound Structure of the Ear cid 127 Outer Ear Pinna Auditory canal cid 127 Middle Ear Stapes Inner Ear Cochlea snail shaped structure of the inner ear Basilar membrane cid 127 Organ of Corti contains receptor cells for sense of hearing Theories of Pitch Pitch corresponds to the frequency of the sound waves Place theory the stimulation of hair cells in different locations on the organ of Corti Frequency theory related to the speed of vibrations in the Basilar membrane Basilar membrane vibrates unevenly when frequency is above 1000Hz place theory Neurons associated with hair cells fire as fast as the Basiliar membrane vibrates up to 1000Hz frequency theory Hearing Impairments Conduction hearing impairment can result from damaged eardrum or damaged stapes cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid 127 cid
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