Chapter 6 Sensation Perception Sensing the World Some Basic Principles Thresholds o Psychophysics o Absolute threshold study of relationship between physical characteristics of stimuli e g intensity and our psychological experiences of them stimulus 50 of the time motivation fatigue o Subliminal Stimulation signal vs background noise experience expectation minimum stimulation needed to detect particular o Signal detection Priming below threshold or conscious awareness Subliminal predisposing one s perception memory or response activation often unconscious of certain associations o Weber s Law o Difference thresholds A K A Just Noticeable Difference or JND to be detectable the stimuli must vary by constant minimum difference a person can detect between 2 stimuli half the time proportion not constant amount it s not the amount of difference that matters it s the proportion of difference that matters if a stimulus in your environment remains constant you stop noticing it diminishing sensitivity to unchanging stimulus o Sensory Adaptation Vision Tranduction Properties of the stimulus Stimulus Input Light Energy transforming one form of energy to another o Wavelength the distance from the peak of one wave to the peak of o Wavelengths give you a hue o Shorter wavelengths are blue in color while longer wave lengths are another wave reddish o High amp bright low amp low or dim The Eye o Pupil hole in your eye the whole purpose is to let light energy enter o Iris the muscle that surrounds the pupil main function is to regulate the amount of light that s allowed to enter o Cornea clear coating on the eye one function of the cornea is to focus the light to some extent serves as a protective mechanism o Lens focuses light sits behind the pupil o Retna located all along the back of the eye where photo receptors are the things that actually detect the light energy o Fovea point of central focus The Retna Visual Information Processing o Cone help you see light in color help you see things in detail highest concentration is right at the phobia o Rods help you see black and white active during night time conditions you use rods when there s not a lot of light more numerous in the periphery of the retna sparsest at the fovea o Feature Detectors nerve cells neurons that respond to specific o Information comes in through each of our eyes crosses at the optic chiasm and carries information to the thalamus and then the info is processed in the opsipital lobe features of the stimulus e g shape angle movement more complex patterns different supercell clusters are responsible for processing faces houses chairs or houses chairs simultaneously vs serial processing processing many aspects of a problem receive info from feature detectors and respond to o Parallel Processing o Supercell clusters Color Vision o The wavelengths of the light waves that an object reflects determine the color that we see o Young Helmholtz trichromatic theory color receptors red green blue vision red green yellow blue white black o Opponent process theory retina contains 3 different opposing retinal processes allow for color Hearing Sound Waves stimulus for hearing perception Audition technical term that we use for our sense of hearing o Amplitude loudness height of wave gives us info about volume taller the amp louder the sound o Frequency pitch frequency is how many waves in a unit of time Short waves high pitch piccolo Long waves low pitch tuba The Ear o Pinna to act like a funnel ear trumpet o Auditory Canal where the sound waves travel through o Middle Ear Eardrum a piece of tissue that s pulled tight as the sound vibrations enter the ear they hit the eardrum and cause it to start to vibrate Vibrations in eardrum cause the hammer anvil and stirrup to vibrate o Inner Ear Cochlea main structure filled essentially with water Movement of the stirrup causes movement in the fluid of the cochlea movement in the fluid in the cochlea causes movement in the cilia hair cells that line the movement in the hair cells sends info out to the brain o Volume is measured in decibel s the arbitrary threshold of human hearing is 0 decibel s lack of human ability to perceive vibrations in the air Decibels above 82 84 could cause permanent damage to your hearing o Perceiving Loudness Number of activated hair cells Place theory Frequency theory o Perceiving Pitch places along basilar membrane auditory nerve is monitored frequency is that required o Hearing Loss the Deaf Culture Volley principle different sound waves trigger activity at different frequency of neural impulses traveling up neural cells alternate firing so combined Conduction hearing loss caused by damage to the structures in the ear that conduct sound waves to the cochlea Sensorineural hearing loss receptors or associate nerves aging exposures to loud sounds then stimulate auditory nerve through electrodes threaded into the cochlea caused by damage to hair cell converts sounds to electrical signals which Cochlear implant o A school of thought emphasizing that the whole is different than the organization of visual field into its objects figures tendency to organize stimuli into coherent groups Proximity things that are organized together in a space are perceived as being members of the same group Similarity things that are alike tend to get grouped together Continuity we like to view things as a continuous segment rather then being broken up Connectedness things that are physically connected are perceived as being members of the same group Closure the tendency to psychologically fill in lines edges that aren t physically there Perceptual Organization Gestalt an organized whole sum of its parts o Figure ground Form Perception and surroundings ground o Grouping Depth Perception images that fall on the retina are in 2 D ability to perceive the world in 3 D even though the