PSY 456; Unit 1 Study Guide
PSY 456; Unit 1 Study Guide PSY 456
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This 21 page Study Guide was uploaded by Brianna on Thursday February 11, 2016. The Study Guide belongs to PSY 456 at Colorado State University taught by Amberg in Spring 2016. Since its upload, it has received 130 views. For similar materials see Sensation & Perception in Psychlogy at Colorado State University.
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Date Created: 02/11/16
S&P Unit 1 Study Guide Sensation & Perception Unit 1 Study Guide Chapter 1 ● Terms: ○ Environmental Stimuli: all objects in environment ○ Attended Stimulus: the object the observer is consciously attending to ○ Transduction: when environmental energy transforms into electrical energy ○ Bottomup Processing: processing based on incoming stimuli from environment ○ Topdown Processing: processing based on perceivers previous knowledge ○ Absolute Threshold: smallest amount of energy needed to detect stimulus 50% of time ○ Difference Threshold: smallest detectable difference between 2 stimuli ■ relationship explained by Weber’s Law ○ Response Compression: as intensity increases, perceived magnitude increases slower ○ Response Criterion: a person’s response bias ○ Power Function: relationship between intensity and perceived magnitude ■ relationship explained by Steven’s Power Law ○ Response Expansion: as intensity increases, perceived magnitude increases quicker ○ Signal Detection Theory: a model/data analysis method for decision for problems with uncertainty ○ Phenomenological Method: what is perceived or when the perception occurs ● The Perceptual Process 1. Stimulus a. Environmental Stimulus b. Attended Stimulus c. Stimulus on the Receptors ■ stimulus transforms into internal representation 2. Electricity a. Transduction b. Transmission ■ information from eye travels to brain ■ Receiving Areas (for vision) ● Occipital Lobe ● Temporal Lobe S&P Unit 1 Study Guide ● Parietal Lobe c. Processing ■ Neural Processing ● changes occur as signals and are transmitted through neurons ■ more information = less successful processing 3. Experience and Action a. Perception ■ occurs as a conscious experience ■ stimuli leads to signals that lead to perception b. Recognition ■ occurs when object is categorized and given meaning c. Action ■ occurs when motor activity is initiated in response to recognition ■ you must perceive to act/not act upon ● Perception Approaches 1. Psychophysical Approach ○ stimulusperception relationship ○ uses observer feedback 2. Physiological Approach ○ stimulusphysiology or physiologyperception relationship ○ uses electrical responses, anatomy, chemical processes ● Measuring Perception (Psychophysical Methods) ○ Method of Limits ■ stimuli of different intensities presented in ascending and/or descending order ● subject responds if perceive/lose stimulus ● crossover point is threshold ● calculate a mean to get threshold ○ Method of Adjustment ■ stimulus intensity is adjusted continuously until detected ● observer adjusts intensity ● starts low then increase ● repeated trials averaged for threshold ○ Method of Constant Stimuli ■ five to nine stimuli of different intensities are presented randomly ● multiple trials are done ● threshold is the intensity that results in detection in 50% of trials ○ Difference Threshold (Difference Limit) ■ as magnitude of stimulus increases, so does difference threshold S&P Unit 1 Study Guide ● when difference between standard and comparison weights is small, harder to detect difference ■ Weber’s Law explains the relationship ■ Fecher made mathematical explanation (Weber’s Fraction) ○ Influences ■ Liberal Responder ● responds “yes” if there is the slightest possibility of experiencing stimulus ● high in false alarm rate ■ Conservative Responder ● responds “no” if there is any doubt ● high in miss rate ■ Neutral Responder: in the middle ● Magnitude Estimation ○ above threshold stimuli presented ○ subject given standard stimuli and value of its intensity ○ subject compares standard value to test stimuli by assigning number in comparison to standard ■ ex: 2 lbs heavier, 1 lbs lighter ○ Response Compression ■ report minimal change ■ ex: bright to more bright ○ Response Expansion ■ report big change ■ ex: subtle electric shock to increased intensity ● Signal Detection Theory ○ Design ■ in some trials a stimulus is presented, in other no stimulus ■ subject reports if perceived stimulus or not ○ Calculations ■ Hit Rate ● detected stimulus is present ■ Miss Rate ● did not detect stimulus when present ■ False Alarm Rate ● detected stimulus when not present ■ Correct Rejection ● did not detect stimulus when not present ■ Confusion Matrix → ● contains all the information about the observers performance S&P Unit 1 Study Guide ■ No Detection ● always reports seen/not seen/random response ■ Receiver Operating Characteristic (ROC) ● false alarm rate on Xaxis, hit rate on Yaxis ● data along diagonal line is no detection ■ Discriminability ● how well the observer can separate the signal from its absence with some overlap Chapter 2 ● Terms: ○ Accommodation: when ciliary muscles are tightened which causes lens to thicken and focus better ○ Near Point: the distance where your lens can no longer focus on close objects ○ Far Point: distance when light becomes focused ○ Presbyopia: “old eye” ○ Myopia: nearsightedness ○ Hyperopia: farsightedness ○ Opsin: large protein ○ Retinal: light sensitive molecule ○ Visual Transduction: the retinal absorbs one photon ○ Convergence: the synapsing of more than one neuron onto a single neuron ○ Blind Spot: where the optic nerve leaves the eye ○ Dark Adaptation: process of increasing sensitivity to darkness. ○ Isomerization: a photon of light hits retinal, changes shape, so it is sticking out from the opsin ○ Visual Pigment Regeneration: when the retinal and opsin rejoin after isomerization ○ Purkinje Shift: enhances sensitivity to short wavelengths during dark adaptation when the shift from cones to rods occurs ○ Sensory Receptors; specialized neurons that respond to specific kinds of energy ○ Excitatory Transmitters: causes depolarization ○ Inhibitory Transmitters: causes hyperpolarization S&P Unit 1 Study Guide ○ Propagated Response: response is triggered and travels all the way down the axon without decreasing in size ○ SodiumPotassium Pump: moves sodium out of axon and potassium in ○ Selective Permeability: membrane is highly permeable to one specific type of molecule ○ Visual Acuity: ability to see details ● Electromagnetic Spectrum ○ energy = wavelength ○ short gamma rays to long radio waves ○ visible spectrum for humans; 400700 nm ○ most perceived light is reflected light ● The Eye ○ light enters through pupil and is focused by the cornea and lens to a sharp image on the retina ○ rods and cones are the visual receptors in the retina ○ optic nerve carries information from the retina toward the brain ○ Focusing ■ cornea does 80% of focusing ■ lens does the other 20% ● accommodation ● light rays pass through lens sharper and focus on objects near retina ■ Demonstration ● focus on one close object and one further away ● change focus back and forth between two items ○ Loss of Accommodation with Increasing Age ■ Presbyopia; ● hardening of lens and weakening of ciliary muscles ● corrective lenses needed for close activities ■ Myopia; ● focus point is in front of retina ● Cause: ○ Refractive Myopia; cornea or lens bends too much light ○ Axial Myopia; eyeball is too long ● Solutions: ○ move stimulus closer ○ corrective lenses ○ LASIK surgery ■ Hyperopia; ● focus point is behind retina ● constant accommodation can lead to eyestrain and headaches ● Cause: ○ eyeball is too short S&P Unit 1 Study Guide ● Transforming Light Energy into Electrical Energy ○ receptors have outer segment, contains the pigment molecules... ■ Opsin ■ Retinal ○ Visual Transduction ■ retinal changes shape in isomerization ■ Physiologic Evidence ● isomerization triggers enzyme cascade ○ how isomerizing one pigment leads to the activation of a rod receptors ● enzymes facilitate chemical reactions ■ Psychophysical Evidence ● a person can see a light as 7 rods are activated at same time ● a rod can be activated by isomerization of 1 pigment molecule ● Rods and Cones ○ Differences ■ Shape ● Rods; large and cylindrical ● Cones; small and tapered ■ Distribution on Retina ● Fovea; consists solely of cones ● Peripheral Retina; both rods and cones ● Periphery; more rods than cones ■ Amount ● Rods; 120 million ● Cones; 6 million ○ Macular Degeneration ■ fovea and small surrounding area are destroyed ■ creates a blind spot on retina ■ most common in older individuals ○ Retinitis Pigmentosa ■ genetic disease ■ rods are destroyed first ■ foveal cones can also be attacked ■ severe cases result in complete blindness ○ Blind Spot ■ Why we don't notice; ● one eye covers the blind spot of the other S&P Unit 1 Study Guide ● located at edge of visual field ● brain "fills in" the spot ● Dark Adaptation ○ Dark Adaptation Curve → ■ Experiment ● observer looks at fixation point but pays attention to a test light on side ○ Stage One ■ takes place for 34 minutes ○ RodCone Break ■ sensitivity levels off for 710 minutes ○ Stage Two ■ increased sensitivity for another 2030 minutes ● Cone Adaptation ○ test light only stimulates cones ○ Results; ■ sensitivity increases for 34 minutes and then levels off ● Rod Adaptation ○ must use rod monochromat (person with no cones) ○ Results; ■ sensitivity increases for 25 minutes then levels off ○ Visual Pigment Regeneration ■ Process Needed for Transduction ● retinal molecule changes shape and opsin molecule separates ● the retina shows pigment bleaching ● retinal and opsin must recombine to respond to light ● cone pigment regeneration in 6 minutes ● rod pigment regeneration in 30 minutes ○ Spectral Sensitivity ■ Spectral Sensitivity Curve → ■ Rod Spectral Sensitivity ● more sensitive to short wavelength light ● most sensitive at 500 nm S&P Unit 1 Study Guide ● less receptive of bright colors ■ Cone Spectral Sensitivity ● 3 different sensitivities (419, 531, 558) ● most sensitive at 560 nm ● less receptive of dark colors ■ Difference due to absorption spectra of visual pigments ● Electrical Signals in Neurons ○ Structure ■ Cell Body ■ Dendrites ■ Axon/Nerve Fiber ■ Sensory Receptors ○ How Does it Travel ■ stimulus from environment, triggers receptor, travels through synapse to cell body, through dendrites and axon, then keeps going ○ Recording Electrical Signals ■ Small electrodes are used to record from single neurons ● recording electrode is inside the nerve fiber ● reference electrode is outside the fiber ● difference in charge between them is 70 mV ● this negative charge of the neuron relative to its surrounding is the resting potential ○ Neurotransmitters are... ■ released by the presynaptic neuron from vesicles ■ received by the postsynaptic neuron on receptor sites ■ used as triggers for voltage change in the postsynaptic neurons ○ Excitatory Transmitters ■ neuron becomes more positive ■ increases the likelihood of an action potential (neuron firing) ○ Inhibitory Transmitters ■ neuron becomes more negative ■ decreases the likelihood of an action potential ● Action Potentials ○ Basic Properties ■ show propagated response ■ remain the same size regardless of stimulus intensity ■ increase in rate to increase in stimulus intensity ■ refractory period of 1 ms ■ firing rate is 500 to 811 impulses per second S&P Unit 1 Study Guide ■ spontaneous activity that occurs without stimulation ○ Chemical Basis ■ neurons are surrounded by a solution containing ions ● Sodium Ions (Na+); positive ● Chlorine Ions (Cl); negative ● Potassium Ions (K+); positive ■ electrical signals are generated when ions cross the membranes of neurons ■ membranes have selective permeability ● Neural Convergence and Perception ○ Layers of Retina ■ Receptors ■ Bipolar cells ■ Ganglion cells ○ Rods and Cones send signals... ■ vertically through ● bipolar cells ● ganglion cells ● ganglion axons ■ horizontally ● between receptors by horizontal cells ● between bipolar and ganglion cells by amacrine cells ○ Convergence ■ 126 million rods and cones converge to 1 million ganglion cells ■ higher convergence of rods than cones ● average 120 rods to one ganglion cell ● average 6 cones to one ganglion cell ● cones in fovea have one to one to ganglion ■ Rods Become More Sensitive than Cones ● takes less light to respond ● greater convergence increasing likelihood of response ● trade off is that rods cannot distinguish detail ■ Cones Improve Acuity ● 1to1 wiring leads to ability to discriminate details ● trade off is that cones need more light than rods ○ Demonstration ■ foveal acuity superior to peripheral acuity ■ list of letters, focus on one, letters in periphery harder to see ● Infant Visual Acuity ○ Preferential Looking Technique ■ two different stimuli are presented to infant, examiner watches infant's eyes ■ if infant looks at one stimulus more than the other, conclude that they see a difference ■ Why does it work? S&P Unit 1 Study Guide ● Spontaneous Looking Preferences: infants prefer to look at certain types of stimuli ○ Visual Evoked Potential ■ electrodes placed on back of infants head over visual cortex ■ infant looks at stimuli, if detected an electrical response is generated ● response is called visual evoked potential ○ Rod & Cone Development ■ rods almost as good as adults at birth ■ cones spaced out and underdeveloped ● well developed at 6 months Chapter 3 ● Terms: ○ Lateral Inhibition: inhibition that is transmitted across the retina ○ Ommatidia: tiny structures in Limulus eye ○ Neural Plasticity: response properties of neurons can be shaped by perceptual experience ○ Simple Cortical Cells: cells with sidebyside excitatory and inhibitory areas ○ Selective Adaptation: if neurons fire for long enough, they become fatigued, or adapt ○ Selective Rearing: animals are reared in environments that contain only certain types of stimuli ○ Lateral Geniculate Nucleus (LGN): where signals from retina travel to after leaving the eye ○ The Striate Cortex/Area V1: primary visual receiving area in the occipital lobe ○ Sensory Code: representation for perceived objects through neural firing ○ Specificity Coding: specific neurons responding to specific stimuli ○ Distributed Coding: pattern of firing across many neurons codes specific object ○ Sparse Coding: only a relatively small number of neurons are necessary ○ Neural Correlate of Consciousness (NCC): how physiological responses correlate with experience ○ Center Surround Antagonism: the interaction between center/surround regions of receptive fields ● Lateral Inhibition and Perception S&P Unit 1 Study Guide ○ Experiments with Eye of Limulus (horseshoe crab) ■ ommatidia allow recording from a single receptor ■ light shown into a single receptor leads to rapid firing rate of nerve fiber ■ Results: ● adding light into neighboring receptors leads to reduced firing rate of initial nerve fiber ○ Lightness Perception Explained by Lateral Inhibition ■ Hermann Grid ● people see an illusion of gray images in intersections of white areas ● signals from bipolar cells cause it ○ receptors responding to white corridors send inhibiting signals to receptor at the intersection ○ the lateral inhibition causes a reduced response which leads to the perception of gray ■ Mach Bands ● see illusion of enhanced lightness and darkness at borders of light and dark areas ● receptors responding to low intensity (dark) area have smaller output ○ additional inhibition resulting in dark band ● receptors responding to high intensity (light) area have largest output ○ less inhibition resulting in light band ● all receptors are receiving lateral inhibition from neighbor ● amount of inhibition is equal for all receptors ● receptors on the border receive differential (disproportionate) inhibition ■ Simultaneous Contrast ● see illusion of changed brightness of color due to effect of adjacent area ● bright surrounding area sends large amount of inhibition to center ○ darker perception when surrounded by a light area ● dark surrounding area sends a small amount of inhibition to center ○ lighter perception when surrounded by dark area ○ Lightness Perception NOT Explained by Lateral Inhibition ■ White's Illusion S&P Unit 1 Study Guide ● see illusion of lighter and darker rectangles ● lateral inhibition would result in opposite effect ○ rectangle with dark surrounding should appear lighter ○ rectangle with white surrounding should appear darker ● Explanation ○ Belongingness ■ an area's appearance is affected by where we perceive it belongs ■ effect probably occurs in cortex rather than retina ■ exact physiological mechanism is unknown ● Processing from Retina to Visual Cortex and Beyond ○ area of receptors that affects firing rate of a given neuron in the circuit ■ receptors influence what kind of firing happens ○ receptive fields are determined by monitoring single cell responses ■ how many cells respond to what is in field ○ Center Surround Antagonism ■ output of center surround receptive field changes depending on area stimulated ● highest response when only the excitatory area is stimulated ● lowest response when only the inhibitory area is stimulated ● intermediate (quickest) response when both areas stimulated ○ Hubel and Wiesel's Rationale for Studying Receptive Fields ■ Lateral Geniculate Nucleus (LGN) ● Major Functions ○ regulate neural information from the retina to the visual cortex ○ signals are received from retina, cortex, brain stem, thalamus ○ signals are organized by eye, receptor type, and type of environmental information ● have centersurround receptive fields ○ Excitatory and Inhibitory Effects ■ excitatorycenter inhibitorysurround S&P Unit 1 Study Guide ● lot from excitatory, less from inhibitory ■ inhibitorycenter excitatorysurround ● lot from inhibitory, less from surround ● Receptive Fields of Neurons in The Visual Cortex ○ Simple Cortical Cells ■ responds to bars of a particular orientation ○ Complex Cortical Cells ■ responds to movement of a correctly oriented bar across the receptive ﬁeld ○ EndStopped Cortical Cells ■ responds to corners, angles, or bars of a particular length moving in a particular direction ○ Cells as “Feature Detectors” ■ cells respond to specific features of the stimulus, such as orientation or direction ● Feature Detectors and Perception ○ Selective Rearing ■ neurons that respond to these stimuli become more predominate due to neural plasticity ■ Blakemore and Cooper ● reared kittens in tubes with either horizontal or vertical lines ○ both behavioral and neural responses showed the development of neurons for the environmental stimuli ○ heighted the response to horizontal/vertical stimuli ○ Selective Adaptation ■ Physiological Effects ● neuron’s firing rate decreases ● neuron fires less when that stimulus is immediately presented again ● Sensory Code ○ Specificity Coding ■ leads to "grandmother cell" hypothesis ■ Problems; ● too many different stimuli to assign to specific neurons ● most neurons respond to a number of different stimuli ○ Distributed Coding ■ large number of stimuli can be coded by a few neurons ■ doesn’t require specialized neurons for every object ○ Sparse Coding ■ midpoint between specificity and distributed coding S&P Unit 1 Study Guide ● The MindBody Problem ○ Easy Problem ■ Neural Correlate of Consciousness ○ Hard Problem ■ How do physiological responses cause experience? ■ How do physiological responses transform into experience? Chapter 4 ● Terms: ○ Cortical Magnification: a small area of the fovea is represented by a large area on the visual cortex ○ Retinotopic Map: a map where each point on the LGN corresponds to a point on the retina ○ PET: uses a radioactive substance called a tracer to look for disease in the body ○ fMRI: uses MRI technology to measure brain activity by detecting changes in blood flow ○ Tiling: columns working together to cover the entire visual field ○ Double Dissociations; two function involve different mechanism and operate independently ○ Module; a brain structure that processes information about specific type of stimuli ○ Fusiform Face Area (FFA): responds best to faces ○ Parahippocampal Place Area (PPA): responds best to general spatial layout ○ Extrastriate Body Area (EBA): responds best to pictures of full bodies and body parts ● Exploration of Spatial Organization ● Electronic Map on V1 ○ retinotopic map ○ cortical magnification ■ brain imaging (fMRI) proves this ■ stimulated small area of fovea, showed activity in larger area of brain ■ stimulated small area of periphery, smaller area of brain activated ● Cortex Columns ○ Visual Cortex ■ Location columns ● receptive fields at same location on retina are in a column ● similar abilities next to each other ● contains orientation columns ■ Orientation columns ● neurons within columns fire maximally to the same orientation of stimuli ● adjacent columns change preference in an orderly fashion S&P Unit 1 Study Guide ● 1 mm across the cortex represents entire range of orientation ■ Ocular Dominance Columns ● neurons in the cortex respond preferentially to one eye ■ Hypercolumns ● all three columns combined ● processing module ● Contains ○ one location column ○ left and right ocular columns ○ a set of orientation columns ● How do Feature Detectors Respond to a Scene? ○ Tiling ■ there are still gaps in vision that brain fills in ● Streams for Information ○ Lesioning or Ablation Experiments ■ animal trained to indicate perceptual capacities, part of brain is removed/destroyed, retrained ■ Results ● reveal which portions of the brain are responsible for specific behaviors ■ Ungerleider and Mishkin ● Object Discrimination Problem ○ monkey shown object, presented 2 objects. reward for detecting target object ● Landmark Discrimination Problem ○ monkey trained to pick the food well next to cylinder ● ablated part of the parietal lobe or part of temporal lobe ● Results ○ removal of temporal lobe resulted in problems with object discrimination (what/ventral pathway) ○ removal of parietal lobe resulted in problems with landmark discrimination (where/dorsal pathway) ○ Both Pathways ■ originate in retina and continue through 2 types of ganglion cells in LGN ■ have some interconnections ■ receive feedback from higher brain areas ○ Where May be How Pathway ■ dorsal stream shows function for both location and for appropriate action ■ evidence from Neuropsychology S&P Unit 1 Study Guide ● double dissociations ○ Milner and Goodale ■ Patient D.F. ● damage to ventral pathway ● not able to match orientation, but able to orient card in slot ● other patients show opposite ● evidence shows double dissociation between ventral and dorsal pathways ● Behavior of People Without Brain Damage ○ Ganel ■ demonstrate a separation of perception and action in nonbrain damage subjects ■ thought one line was larger than other but fingers showed same ● Modularity ○ Rolls ■ measured the response neurons in the Inferotemporal Cortex of monkeys ● responds best to faces ● little response to nonface stimuli ○ Evidence from fMRI shows ■ fusiform face area ■ parahippocampal place area ■ extrastriate body area ● Where Vision Meets Memory ○ Medial Temporal Lobe (MTL) structures are extremely important in memory ■ H.M. ● damaged hippocampus ● somewhat intact LTM, no STM capacity ■ Quiroga et al. ● recorded neurons in hippocampus and MTL of patients with epilepsy ● some neurons only responded to specific stimuli, but probably do not only respond to that stimuli ● Experience and Neural Responding ○ ExperienceDependent Plasticity in Humans ■ brain imaging experiments show areas that respond best to letters and words ■ fMRI experiments show that training results in areas of the FFA responding best to: ● Greeble stimuli S&P Unit 1 Study Guide ○ don’t resemble faces, upon training able to identify and FFA responds ● Expertise ○ FFA responds when viewing thing of expertise Practice Test Questions Chapter 1 ● 4 reasons why it is important to study perception ● Define “topdown” and “bottomup” processing. Give example ● Compare and contrast the five categories of the perceptual process S&P Unit 1 Study Guide ● Name and describe three classical psychophysical methods Chapter 2 ● Name, define, and discuss the treatment for 3 kinds of focusing problems ● Compare and contrast rods and cones ● Identify and describe two retinal disorders that affect rods and cones ● Describe the blind spot and why we are usually not aware of it S&P Unit 1 Study Guide ● Draw a graph of the dark adaptation curve. Then describe the methodology used to isolate the rod component of the curve, and the cone component Chapter 3 ● Describe and give example of lateral inhibition. Then describe white’s illusion and describe possible explanation ● Discuss research that shows that selective rearing result in neural plasticity S&P Unit 1 Study Guide ● Describe how information would be represented under each of the following representational schemes; specificity, distributed, and sparse coding Chapter 4 ● Describe research that shows cortical magnification occurs in humans ● Describe the functions of the ventral and dorsal stream. Support these with relevant studies ● Compare and contrast FFA, EBA, PPA ● How does the FFA relate to expertise S&P Unit 1 Study Guide
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