PSY 1001 1nd Edition Exam 2 Study Guide Lectures 10 18 Lecture 10 3 3 14 Sensory Input and Vision Sensation Detection of physical energy by our sense organs which then send that info to the brain Perception Brain s interpretation of raw sensory data one step further than sensation Transduction External stimulus is converted by a sense receptor into neural activity Sensory adaptation Activation is highest when the stimulus is first detected Psychophysics Study of how we perceive sensory stimuli based on their physical characteristics Absolute threshold Lowest level of a stimulus we can detect 50 of the time i e a single candle 30 miles away or 50 odorant molecules the just noticeable difference is the smallest amount of stimulus change we can detect Weber s Law The stronger the stimulus the greater the change necessary for the detection of a difference Signal Detection Theory How can you detect a signal Light Human visible spectrum is only a narrow band of light that we respond too Parts of the eye Lens focuses photons onto back of eye so does cornea Image is turned upside down and right to left on the back of the eye Cones focused in fovea sensing color sees green red and blue Rod focused in retina good at sensing light Optic nerve meets with brain thalamus then into cortex creates a blind spot Trichromatic theory Color vision is based on our sensitivity to 3 primary colors consistent with 3 types of cones in eyes and explains color blindness Opponent Process Theory Sees color vision as a function of complementary opposing colors i e red vs green or blue vs yellow Visual pathways Right visual field hits left part of eye then goes into left brain opposite for left visual field One pathway leads to parietal lobe which processes visual form position and motion Another pathway leads to the temporal lobe which processes visual form and color Simple cells Detect orientation specific slits of light in a particular location Complex cell Also orientation specific but less dependent on location than simple cells Lecture 11 3 5 14 More Vision and Hearing Gnostic cell Neurons like groups of features which describe an object Each cell absorbs info about one part of an object then come together to identify the whole object Blindness Results in heightened touch reorganization of visual cortex Blindsight Above chance visual performace of cortically blind indivisual with damage to area V1 Cortex part of brain damaged Visual agnosia Object recognition deficit damage to higher visual cortical areas Can t identify very specific things but after touching can identify it Bottom up Top down processing Perception depends on sensory data and beliefs expectations Perceptual sets Occur when expectations influence our perceptions Perceptual constancy Allows us to perceive stimuli consistently across conditions Gestalt Principles Rules that govern how we perceive objects as wholes within their overall context Whole is more than sum of its parts i e a square is more than 4 lines How we determine motion Brain compares visual frames of what is to what was Motion blindness Inability to perceive seamless motion Monocular depth Using only one eye Can determine relative size texture gradient interposition linear perspective height in plane light and shadow Binocular depth Requires both eyes Disparity and convergence Perception deceives us often Illusions Sound Vibration traveling through a medium usually air Pitch Wave frequency Hz Loudness Amplitude of sound waves dB Timbre Complexity of sound i e different notes playing the same pitch Parts of ear Pinna outer ear channels sound into ear canal Ear canal conducts sound waves to ear drum Ear drum vibrates in response to sound waves Cochlea converts vibration into neural activity Transduction occurs in inner hair cell Place theory Different tones excite different areas of the basilar membrane cochlea and primary auditory cortex Frequency theory 20 100 Hz and Volley theory 100 5000 Hz Neurons rate of firing reproduces the frequency of the sound explains perception of low and middle pitches Cochlear implant Put electrode wires up spiral put a auditory sensory outside of ear takes place of hair cells allows person to hear Lecture 12 3 10 14 More Sound and Taste Sound Localization Rely on binaural cues absorbing info in 2 places to tell us where sounds are coming from cues include differences between the 2 ears in the timing and intensity of sound waves Auditory pathways Info goes from auditory nerve to the opposite side s auditory cortex Somatosensory system responds to Pressure temperature and injury We sense these with Specialized nerve endings in the skin and with free nerve endings around 500 000 sensory receptors that detect pressure are located in skin Pacinian corpuscle Specialized for deep pressure Meissner s corpuscle Specialized for light touch Ruffini ending Specialized for skin stretching help determine where limb is in space Free nerve ending Pain receptor Somatosensory pathway Somatic nerves carry info to spinal cord spinal reflexes may be activated connects in brain stem thalamus touch somatosensory cortex and association cortices OR pain somatosensory cortex and limbic areas Can pain perception be influenced Yes by experience context and expectation Taste Chemicals dissolved in saliva 5 elementary tastes Sweet Sucrose salty Salt Sour Ascorbic acid Bitter Umami savory Taste map FALSE suggests that tastes are better perceived in some areas of the tongue Instead bud is split up into different portions which each perceive a specific taste Role of serotonin in eating Less serotonin not transducing tastes as well Flavor Taste smell our senses of smell and taste enter the brain by different routes but converge in the orbitofrontal cortex Supertasters Have more preceptors really sensitive to bitter don t like sweets very picky eaters Perception of taste Not all about taste buds differ by culture hotter climate usually means more spices individual histories differ food you prefer partially determined by exposure from parents Olfactory system Sense of smell Pheromones Odorless airborne molecules Crucial role in behavior of many animals Role in synchronizing menstrual cycles Can affect moods Summary of sense Taste chemicals dissolved in saliva Vision photons of light Audition sound waves compressions of air Somatosensory pressure temperature pain Olfaction chemicals in air Lecture 13 3 12 14 Sleep and Dreaming Restorative theory We sleep to conserve energy and to