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Wilfrid Laurier University
Elizabeth Olds

PS 262 Exam Review Chapter 1: Introduction  Perceptual Process o Sequence that works together to determine our experience of and reaction to stimuli in the environment o Stimulus  What is out there in the environment, what we actually pay attention to and what stimulates our receptors  Impinges on your sense  Environmental  All of the things in our surroundings that we can potentially see  On the Receptors  Look directly at an object and it creates an image on the receptors of the retina ( line back of the eye) o Sensory Cue  Signal that can be extracted from sensory input  State of some property in the world o Integrating information  Actively interpret the environment  Work with senses and knowledge o Electricity  Electrical signals that are created by the receptors and transmitted to the brain  Transduction  Transformation of one form of energy into another form of energy  Receptors create electrical energy in response to light  Transmission  Signal activates other neurons which activate more, eventually activate the brain  One neuron actives others  Processing  Neural processing o Interaction between neurons o Brain turns signal into perception of image o Experience and Action  Perceive, recognize and react to stimuli  Perception  Conscious sensory experience  Experience of seeing the image  Recognition  Ability to place an object in a category that gives it meaning  Visual Form Agnosia o Inability to recognize whole objects  Action  Motor activities such as moving the head or eyes and locomoting through the environment  Perception often leads to action o Knowledge  What we bring to the perceptual process  Categorization of objects  Data-based processing (bottom-up)  Based on incoming data  Knowledge based process (top-down)  Sensory Ques o Taking aspects of the environment to figure out what something is  Psychophysical Approach o How we use info from the environment to create perceptions o Gustav Fechner  Psychophysics  Use of quantitative methods to measure relationships between stimuli and perception  Any measurement of the relationship between stimuli and perception  Physiological Method o How are properties of objects in the environment represented by activity in the nervous system  Relationship between stimulus and physiology o Activity in the brain  Neurons  Units of processing o Relationship between nerve impulses and specific perceptions  Synapse o Gap between two neurons o Presynaptic neuron communicates with post synaptic neurons by sending information o Spontaneous activity level  Resting rate of firing without stimulation  Activation increase fire rate about spontaneous rate  Inhibition decrease firing rate o Localization of function  Where in the brain particular info is processed  Sensory coding  How features of environment are represented o Specific  Neurons codes for certain features o Pattern  Firing codes for a feature distributed over many neurons o Techniques  Lesion  If a part of the brain is removed, and a particular ability disappears , then that part of the brain is normally involved in this ability  Single-cell recording  Specify response properties of singles neurons  Present stimuli and measure  Neuroimaging  Able to give functions for broader areas of the brain  Activity in brain = perceptual tasks  MRI, CAT, PET o Measuring the relationship between stimuli and physiological processes and between physiological processes and perception o Measure electrical responses in the nervous system o How are properties of objects in the environment represented by activity in the nervous system? o Which neurons are fired and when?  Cognitive Approach o Neisser  2 directions of info processing  Bottom-up o Construct perception by analysing info falling on receptors  Top-down o Starts with analysis of high-level info o How the knowledge, memories, and expectations that people bring to the situation influence their perception o Looking at the brain similarly how info processing is in computers  Phenomenological method o Asks person to describe what he or she is perceiving or to indicate when a particular perception occurs September 20  Perceiving things that aren’t there o Perception is not direct  Perception can be different from physical stimulus o Tables both same size o Face perception  Good for right side up but not upside down Chapter 1B  Psychophysics o Determining quantitative relationships between the external (physical ) stimulus and internal experience ( perception?)  Gustav Fechner  Psychometric Function o Present different stimulus intensities  Task = detection o % detection vs stimulus intensity o Detection increases as light intensity increases o S shape graph  Absolute Threshold o Smallest amount of stimulus energy necessary for the observer to detect a stimulus o Amount of stimulus needed for 50% = o Method of Limits  Descending order  100 yes, then 90 yes, 80 no  Crossover point, average of 80 and 90 = 85 units  Ascending order  70 no, 80 no , 90 no, 100 yes  Crossover 75  Average between 2 = 90 units o Method of Constant Stimuli  Similar but present in a random order o Method of Adjustment  Observers will say can just barely detect  Use knob/dial to change intensity  Difference Threshold o Smallest difference between two stimuli a person can detect o JND  Just Noticeable Difference  Magnitude Estimation o Shows relationship between intensity of a stimulus and perception of magnitude o Electric shock shows the opposite effect  Response expansion  As intensity increased perceptual magnitude increases more than intensity  Response compression  Double intensity not double perceived brightness o Power functions n  Steven’s power law: P=KS  Perceived magnitude , equals and constant , K, times the stimulus intensity, S, raised to a power of n . o First present standard stimulus with value 10, ask to assign numbers to other light intensities o Double intensity=/ not double perceived brightness o Response compression  As intensity is increased the magnitude increases but not as rapidly as the intensity  Search o Respond as quickly as possible o Visual search task o Reations time  The time between presentation of the stimulus and the observer’s response to the stimulus Appendix o Response Criterion o Amount of sensory info observer requires for saying “yes” o Low criterion  Say yes even if don’t perceive much evidence  Liberal responder o High criterion  Less willing to say yes  Conservative o Response is effected by sensitivity and observer’s response criterion o Catch trials o No target o Method of constant stimuli has none o Can Ricky tell the difference between tone and no tone o Payoffs o Always say yes to stimulus, pay off causes change in bias o ROC curve o Receiver operating characteristic o Performance on detection task o X axis - % False Alarms o Y axis =% hits o Neutral point o Data will fall on ROC curve, different people with different points = different sensitivity Chapter 2: Intro to the Physiology of Perception  Neural Processing o Info is analysed, interpreted so that the signal is easy for our perceptual system to comprehend o Aristotle o The heart was the seat of the mind and the soul saw human health, thoughts, and emotions, as being determined by four different “spirits” flowing from the ventricles o Ventricles o Cavities in the center of the brain o Rene Descartes o Pineal gland  Located over the ventricles  Seat of the soul o Thomas Willis o Brain is responsible for mental functioning o Different function are located in different regions of the brain o Disorders of the brain involve disorders of chemistry o Reticular Theory o The nervous system consisted of a large network of fused nerve cells o Neuron Theory o Stated that the nervous system consisted of distinct elements or cells o Staining  Chemical technique that caused nerve cells to become coloured so they stood out from surrounding tissue o Doctrine of specific nerve energies  Johannes Mueller  Our perceptions depend on “nerve energies” reaching the brain and that the specific quality we experience depends on which nerves are stimulated o Measuring individual neurons o Determine how and which neurons respond to stimuli in the environment and how neurons work together in neural networks o Basic Structure of the Brain o Cerebral cortex  Covers the surface of the brain  Holds processes for perception, and other functions  Language, memory, thinking  Modular organization  Specific functions are served by specific areas of the cortex  Senses are organized in primary receiving areas o Occipital lobe  Vision o Temporal lobe  Hearing o Parietal  Skin senses o Frontal  Signals from all senses  Coordinate perception from multiple sense o Structure of Neurons o Body  Keep cell alive o Dendrites  Branch to receive signals o Axon/ nerve fibre  Filled with fluid that conducts electrical signals o Receptors  Specialized neurons that respond to enviro stimuli such as pressure for touch o Recording Electrical Signals in Neurons o Nerve  Consists of axons of many neurons o Microelectrodes  Small shafts of glass or metal with very fine tips are used to record signals form single neurons  Measure the difference in charge between two electrodes o Resting Potential  Difference -70 millivolts  No signals in the neuron o Action Potential  Charge rises to +40 inside becomes negative until back to rest  Ions  Surr
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