Sensation and Perception Chapter 4 PDF

 Sensation and Perception Sensation detection of physical stimulus in the environment it's encoding neural...

 Sensation and Perception Sensation detection of physical stimulus in the environment it's encoding neural and as Signals - a Perception Selection, of organization and interpretation sensory - , Bottom-up processing analysis that begins with the sense receptors - Top-down processing - analysis that integrates sensory input with experience and exception Psychophysics The study of how stimuli are translated into psychological expierence Threshold - detectable or not absolute threshold - detectable 50 % of the time Just noticable difference (JND) - smallest difference in detect Webers law - Size of JND is proportional to size of initial Stimilus ; it is a constant proportion Initial Stimilus↑ and the JNDY Example : lifting weight , the constant proportion is 102/3002 or 1130 , so for every 3002 , in order to detect a change , 102 will be required therefore , if initial stimilus is 6002 , a 202 change will be required to detect a difference If we start with 9002 , 302 will be required ; 12002 , 402 etc. subliminal perception registering sensory input without conscious awareness detectable but weak effects no evidence of coercive effect - , sensory adaption - decline in sensitivity over time vision : The stimilus Light = electromagnetic radiation  Amplitude : Perception of brightness wavelength : Perception of color (300 - 750 perception of human Vision which is measured in nanometers ( Eye converting : light into neural Impulses The eye : housing and channeling The light back to retina - components : Cornea -where light enters the eye Pupil-regulates amount of light Iris-colored of dilates of ring muscle , constricts or via amount light Lens-Focuses the light rays on the refina. (Adjusts curvature , hardens with age) Dilate in that better means it letting more light , so you can see The retina : An extension of the CNS Retina : Absorbs light , processes Images optic disk : optic neve connection/blind Spot Receptor cells Rods - - cones (sensitive to red blue ( , green , Quantity = Cones : 6. 4M Rods : 125 M Location Cones = : Center Rods : Periphery Low light = Cones : no Rods : Yes Colour = Cones : Yes Rods : Yes Detail = Cones : Yes Rod : No Adaption needed becoming more less sensitive to light - or as Information processing Receptive fields : various shapes circular - many are , from the environment light and Lateral antagonism Comparing light : general to the , allows us to see a Contrast Puck out edges The retina and the brain Light- rods and cones > neural signals - bipolar cells -> ganglion cells -> optic nerve Optic chasm opposite half of brain Major pathway - lateral geniculate nucleus (LGN) in thalmus - Primary Visual cortex (occipital lobe Magnocellular : brightness - - Parvocellular : Colour second pathway superior Collicula thalamus > Primary Visual Cortex Feal > > - - - - Hubel and wie - are detectors Early 1960s : Hubel and Wiesel - microelectrode recording of axons in primary visual cortex of animals discovered feature detectors : Neurons that respond selectively to lines edges etc. - , , Basics of color vision wavelength determines color Longer = red/shorter = Violet Amplitude determines brightness Purity determines saturation Therois of color Vision Trichromatic (young and helmholtz) red blue color receptors green - , , opponent process (Hering) pairs of color receptors make antagonistic responses - Percevieng forms , Patterns , and objects Reversible figures Perceptual Sets Inattentional blindness Feature detection theroy : bottom up processing  Form perception Top down contours : processing , eg ; subjective Principles of perception Gestalt Psychologists : The whole is more than the Sum of Its parts - Reversible figures and perceptual Sets demonstrate that the same visual stimulus can result in very different perceptions Recent research Distal (Stimuli outside the body) vs. Proximal (Stimulis Sensory receptors ( Stimuli energies impinging on Perceptual hypotheses - Context The by which interpret the aspects of environment that provide with information how process we our us concerning far near or objects are Depth = distance visual cues Binocular The difference the formed between retinal image both eyes - on - Based on the principles of retinal disparity - convergence Monocular retinal image either eye or alone - - motion pparalax Monocular Cues : Pictorial Static cues or pictorial cues - Typically found on a two-dimensional plane in shadow linear perspective texture gradient interposition relative size height plane and light and - , , , , Stability in the perceptual world : Perceptual constancies Perceptual constancies Stable perceptions amid changing stimuli - - Size - Shape - Brightness - Hue - Location in Space Hearing : The auditory system Stimulus = sound waves (viparations of molecules travelling in air - Amplitude (loudness (Pitch Wavelength - - Purity (timbre) : Purest would be a single frequency of vibration These properties (amplitude , wavelength and purity) interact in a complex way to produce the perception of sound : meaured in cacies second a -" per - Frequency increase = Pitch increase - Perceived loudness doubles about every 6-10dB ; geater than 120cB = pain and possible damage The r ee divisions External & ear (Pinnal : Collets sound ; funnels it along auditory Canal to eardrum stirrup L - Mid c Ile e i ar 1 n 2 ossicles (hammer , anvil , These bones translate large movemen-with little force into small movements with force ; sound are moveable and greater - enters the Cochela of the inner ear via the oval window Inner ear : The Cochela (Greek for "Spiraled-shell Snail" - a fluid-filled , coiled tunnel hair the lined the - contains the cells , auditory receptors , which are up on basilar membrane waves in the fluid of the inner ear stimulate the hair cells ; these hair cells convert the physical stimulation to impulses then sent the through the thalamus (located neural which are via auditory nerve and to the auditory cortex Predominantly in the temporal lubes The auditory pathway sound waves vibrate bones of the middle ear The Stirrup the of Cochela , the fluid Inside in hits against oval window setting motion - - Hair cells are stimulated with the movement of the baslir membrane - The physical Stimulation is converted into neural Impulses which are sent through the thalamus to the lobes auditory cortex (temporal Theories Place ? of hearing : or frequenc Herman von Helmholtz (1863) : Place theroy - specific sound frequencies (Pitch) vibrate Specific portions of the baslir membrane (Places) therefor the hair cells respond independantly Rutherford , 1886 Frequency theroy - Pitch perfection corresponds to the rate or frequency at which the entire baslin membrane vibrates (therefor all of the hair cells vibrate together - Hemholtz (place theroy) is correct except hair cells don't move independantly but vibrate together as suggested by frequence theroy. Georg (1947) : von Bekesy Traveling wave theroy - moves along the baslir membrane peaking at a particular place depending on the frequency of the sound wave Traveling wave theroy - sounds less than 1000H2 : movement of the hair cells on the baslir membrane (Frequency Coding ; frequency theroy between sounds 1000 and 5000H2 : Combination of frequency coding (through volly of firing) and place coding only - , that is. Peaking of pitches over 5000H2 Auditory Localization Intensity (loudness Timing of sounds arriving at each ear - head acts as a "shadow" or partial sound barrier - Timing differences as small as 1/100 , 000 of a second (timing of the arrival of sound in each earl Localizing low-frequency sounds seem to be determined primarily by timing differences. to Localizing high-frequency sounds seem be determined primarily by intensity differences The chemical Senses : Taste Taste (gustation ) - Physical Stimulus : soluble chemical substances - Taste receptor cells found in taste buds Pathway : Taste buds neural impulse thalamus ( Cortex - four primary tastes : sweet sour bitter, salty - , , Taste : learned social and processes The chemical senses : smell Smell (olfaction ( Physical Stimuli : Substances carried in the air - - dissolved in fluid : the mucus in the nose - olfactory receptors = Olfactory Cilia - Pathway : Olfactory Cilial neural impulsed olfactory nerve olfactory bulb ) cortex does thalamus. go through - not skin senses : Touch - Physical Stimuli = mechanical , thermal , and chemical energy impining on the skin - Pathway : Sensory receptors) Spinal column) brainstems cross to opposite side of brain thalamus ( lobe Somatosensory cortex (parietal - Temperature : free nerve endings in the skin Pain receptors : free nerve endings - - Two pain pathways : fast (a-delta fibres) vS. Slow (C fibres TherSeekinestheticadvestible a t Cm of the body same pathways as touch but the two types of information are kept separate - Vestibular system : - equilibrum/balance - hair cells in semicircular canals in the inner ear