first exam study guide psychology intro
first exam study guide psychology intro PSY 151
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This 29 page Study Guide was uploaded by Patrece Savino on Sunday February 14, 2016. The Study Guide belongs to PSY 151 at Wake Forest University taught by Dr. Schrillo in Winter 2016. Since its upload, it has received 56 views. For similar materials see Intro to Psychology in Psychlogy at Wake Forest University.
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Exam #1: Topics to Master Outline Chapter 1: The Science of Psychology 1. What is Psychology? Psychology is the science of behavior We examine human behavior because… o Root of many problems in the world o Curiosity about self and world 2. Explaining Behavior Describing behavior: categorizing and measuring Identify the causes of behavior: causal events 3. Fields of Psychological Research Physiological: the branch of psychology that studies the physiological basis of behavior; nervous system Comparative: the branch of psychology that studies the behavior of members of a variety of species in an attempt to explain behavior in terms of evolutionary adaptation to the environment Behavior genetics: the branch of psychology that studies the role of genetics in behavior Cognitive psychology: the branch of psychology that studies mental processes and complex behaviors such as perception, attention, learning and memory, verbal behavior, concept formation, and problem solving Cognitive neuroscience: the branch of psychology that attempts to understand cognitive psychological functions by studying the brain mechanisms that are responsible for them Developmental: the branch of psychology that studies the changes in behavioral, perceptual, cognitive, social, and environmental capacities of organisms as a function of age and experience Social: the branch of psychology devoted to the study of the effects people have on one another’s behavior Personality: the branch of psychology that attempts to categorize and understand the causes of individual differences in temperament and patterns of behavior Evolutionary: the branch of psychology that explains behavior in terms of adaptive advantages that specific behaviors provided during the evolution of a species. Evolutionary psychologists use natural selection as a guiding principle. CrossCultural: the branch of psychology that studies the impact of culture on behavior Clinical: the branch of psychology devoted to the investigation and treatment of abnormal behavior and mental disorders 4. Applied Psychology Type of Psychologist Area of Application Typical Employment Setting Clinical neuropsychologists Identification and treatment Hospitals, in association of behavioral consequences with specialists of nervous system disorders and injuries Clinical psychologists Identification, assessment, Private practice, hospitals and treatment of mental disorders Community psychologists Welfare of individuals in Community organizations the social system, especially those who are disadvantaged Consumer psychologists Motivation, perception, Corporations and learning, and purchasing engineering agencies behavior of individuals in the marketplace Engineering psychologists Perceptual and cognitive Corporations and and ergonomists factors in the use of engineering agencies machinery Forensic psychologists Behavior as it relates to the Private law firms and public legal and justice system agencies in the justice system Health psychologists Behavior that affects health Hospitals, government and lifestyle agencies, and corporations Organizational Behavior in industrial work Corporations and psychologists processes government agencies School psychologists Behavioral issues of Educational agencies and students in the school institutions setting 5. The Rise of Psychology as a Science Rationalism: the philosophical view that all knowledge is obtained through reason Empiricism: the philosophical view that all knowledge is obtained through observation and experience Dualism: the philosophical belief that reality consists of mind and matter Philosophical Roots of Psychology o Rene Descartes: Dualist; rationalist Physiological psychology; reflexes o John Locke: Monist; empiricist o James Mill: Materialist Biological Roots of Psychology o Johannes Muller: doctrine of specific nerve energies: observation that different nerve fibers convey specific information from one part of the body to the brain or from brain to one part of the body o Pierre Flourens: experimental ablation: the removal or destruction of a portion of the brain of an experimental animal for the purpose of studying the functions of that region o Paul Broca: localization of speech production o Hermann von Helmholtz: the mind is within the brain o Ernst Weber: psychophysics Trends in the Development of Psychology Early Years: o Structuralism: the system of experimental psychology that began with Wundt; emphasized introspective analysis of sensation and perception Introspection: looking within in an attempt to describe memories, perceptions, cognitive processes, or motivation Wundt: father of psychology, Introspection o Functionalism: an approach to understanding species’ behaviors and other processes in terms of their biological significance; this approach stresses the usefulness of such processes with respect to survival and reproductive success Darwin, James: biological emphasis o Psychodynamic theory Freud Psychology in transition: o Experimental emphasis Baldwin, Calkins o Behaviorism: a movement in psychology that asserts that the only proper subject matter for scientific study in psychology is observable behavior Thorndike, Pavlov, Watson, Skinner, Washburn The law of effect: Thorndike’s statement that stimuli that occur as a consequence of a response can increase or decrease the likelihood of an organism’s making that response again o Humanistic psychology: an approach to the study of human behavior that emphasizes human experience, choice and creativity, self realization, and positive growth Rogers Reaction against behaviorism and Freud o Cognitive Revolution: Gestalt psychology: a movement in psychology that emphasized that cognitive processes could be understood by studying their organization, not their elements Wertheimer Cognitive psychology Kosslyn o Biological Revolution: emphasis on neurobiology Physiological psychology Hebb Chapter 2: The Ways and Means of Psychology 1. The Scientific Method in Psychology The scientific method allows us to determine the causes of phenomena 3 basic forms of scientific research: o naturalistic or clinical observations o correlational studies: cannot infer causation, just relationship o experiments: determine causal relationships 5 steps in an experiment: o Identify the problem o Design an experiment Independent variables Dependent variables Confounds: unexpected variables introduced during an experiment Experimental Group Control Group Operational Definitions: how we take something and put it into data that we can actually measure Ex. an operational definitions of your knowledge of psychology is your score on the exam Counterbalancing: changing the order of the stimuli to prevent confounding o Perform the experiment Reliability of measurements: Are they repeatable? Subjectivity affects reliability Interrater variability: the degree to which two or more independent observers agree in their ratings of an organisms behavior; often used in more subjective experiments Selecting the participants: Random assignment reduces confounding Expectancy effects: Participant expectations o Singleblind experiments: an experiment in which the researcher knows the value of the independent variable but the participant does not Experimenter expectations o Doubleblind experiments: an experiment in which neither the researcher nor the participants know the value of the independent variable o Examine the data o Communicate the results What does your experiment mean in the real world? (Haddock and Zanna) Generalization: can you apply your results to the population from which you took your sample from? 2. Ethics Research with human participants o Requires compliance with the following principles: Informed consent Confidentiality Minimal risk Debriefing Research on animals o Must respond to following questions: Is the research important and worth doing? Have we minimized harm to the animals? Are the animals getting the best possible care? Are the animals being treated humanely? 3. Understanding Research Results Descriptive statistics: what are the results? o Numerical descriptors Central tendency: mean, median, mode Dispersion: range, variance, and standard deviation o Measurement of relations Correlation coefficients between 0 and 1 Can be +/ depending on direction of the relationship Closer to 1 or 1, stronger the relationship Inferential statistics: distinguishing chance from significance o Calculates the probability that the results are due to chance (statistical significance) Chapter 4: The Brain and its Components 1. The Brain & Its Components The structure of the nervous system o Central nervous system Brain 3 major parts: brain stem, cerebellum, cerebral hemispheres brain stem: the “stem” of the brain; controls physiological functions and automatic behaviors; contains the medulla, pons, and midbrain cerebellum: a pair of hemispheres resembling the cerebral hemispheres but much smaller and lying beneath and in back of them; controls posture and movements, especially rapid ones cerebral hemisphere: the largest part of the brain; covered by the cerebral cortex and containing parts of the brain that evolved most recently Spinal cord: a long, thin collection of neural cells attached to the base of the brain and running the length of the spinal column o Peripheral Nervous System Cranial nerves: a bundle of nerve fibers attached to the base of the brain; conveys sensory information from the face and head and carries messages to muscles and glands Spinal nerves: a bundle of nerve fibers attached to the spinal cord; conveys sensory information from the body and carries messages to muscles and glands Cells of the nervous system o Neurons: elements of the nervous system that bring sensory information to the brain, store memories, reach decisions, and control the activity of muscles o Glia: assist neurons by holding them in place, guide developing neurons from their place of origin to their final resting place, manufacture chemicals that neurons need to perform tasks, absorb chemicals that may impair neuron’s functioning o Dendrites: treelike parts of a neuron on which other neurons form synapses o Soma: a cell body; the largest part of a neuron; controls metabolism/maintenance of a cell o Axon: a long, thin part of a neuron attached to the soma; divides into a few or many branches ending in terminal buttons; carries messages away from the soma toward the cells with which the neuron communicates o Terminal button: the rounded swelling at the end of a neuron that releases a neurotransmitter o Neurotransmitter: a chemical released by the terminal buttons that causes the postsynaptic neuron to be excited or inhibited o Myelin sheath: the insulating material that encases most large axons; produced by glial cells; white matter; part protein part fat The Excitable Axon: Action Potential o Action potential: the message carried by an axon; an electrical current o resting potential: the membrane potential of a neuron when it is not producing an action potential o Ions are positively or negatively charged particles inside the axon and in the fluid that surrounds it Produced when various substances are dissolved in water (ex. table salt) Membrane of axons contain special proteins that control the flow of ions Ion channels: a special protein molecule located in the membrane of a cell; controls the entry or exit of particular ions Ion transporters: a special protein molecule located in the membrane of a cell; actively transports ions into or out of the cell o An action potential is an “allornone” event either it happens or it does not Allornone law: the principle that once an action potential is triggered in an axon, it is propagated, without becoming smaller, to the end of the axon Sensory neurons: receive information from sensory organs such as they eyes Motor neurons: neurons whose axons form synapses with a muscle How can sensory and motor neurons tell the body what to do? QUANTITATIVE INFORMATION FROM THE AXON’S RATE OF FIRING Communication with other cells: Synapses o Synapse: the junction between the terminal button of one neuron and the membrane of a muscle fiber, a gland, or another neuron o Presynaptic neurons and postsynaptic neurons before/after the synapse o Excitatory and inhibitory synapses can be affected by neurotransmitters o Neurotransmitter receptor: a special protein molecule located in the membrane of the postsynaptic neuron that responds to molecules of the neurotransmitter 2. Drugs and Behavior Effects of Drugs on Synaptic Transmission (see diagrams in the book) o Drugs that affect thoughts, perceptions, emotions, and behavior affect the activity of neurons in the brain Communication between neurons involves the release of neurotransmitters either excite or inhibit the activity of the post synaptic cell o Drugs can: Stimulate or inhibit the release of neurotransmitters on postsynaptic receptors Some drugs stimulate certain terminal buttons to release neurotransmitter continuously, even when the axon is not firing Block these effects Neurotransmitters produce their effects by stimulating postsynaptic receptors excites or inhibits the postsynaptic neurons by opening their ion channels & permitting ions to enter or leave the neurons Some drugs mimic the effects of particular neurons by directly stimulating particular kinds of receptors even when the neurotransmitter is not present Other drugs block these receptors, making them inaccessible to the neurotransmitter and thus inhibiting synaptic transmission Or interfere with the reuptake of a neurotransmitter once its released Molecules of the neurotransmitter are released by a terminal button, stimulate the receptors in the postsynaptic membrane, and are then taken back into the terminal button Some drugs inhibit this process so that molecules of the neurotransmitter continue to stimulate the postsynaptic receptors for a long time o INCREASES the effect of the neurotransmitter Neurotransmitters, their actions, and drugs that affect them o Most synaptic activity in the brain is accomplished by two neurotransmitters: glutamate & GABA Glutamate – the most important excitatory neurotransmitter in the brain and spinal cord With the exception of painful stimuli, all sensory organs transmit information to the brain through axons whose terminals release glutamate NMDA receptor (one type of glutamate receptor) plays role in effects of environmental stimulation on the developing brain and is also responsible for many of the changes in synaptic connections that are responsible for learning o Partially deactivated by alcohol blackouts/no memory GABA – the most important inhibitory neurotransmitter in the brain Barbiturates – a drug that causes sedation; one of several derivatives of barbituric acid o in low doses, barbiturates have calming effects o in progressively higher doses, they produce difficulty in walking, talking, unconsciousness, coma, and death Ethyl alcohol – most commonly used depressant drug; active ingredient in alcoholic beverages o Acts on the GABA receptor o Effects of alcohol and barbiturates are additive: moderate dose of alcohol plus moderate dose of barbiturates can be fatal Antianxiety drugs – a “tranquilizer,” which reduces anxiety o Members of a family known as benzodiazepines – a class of drug having anxiolytic (“tranquilizing”) effects, such as diazepam (Valium); much safer than barbiturates o Act on the GABA receptor on neurons in various parts of the brain, including region involved in fear and anxiety Acetylcholine (ACh) – a neurotransmitter found in the brain, spinal cord, and parts of the peripheral nervous system; responsible for muscular contraction three systems have received the most attention from neuroscientists: o one system activates the brain mechanisms responsible for REM sleep – the phase where most dreaming occurs o one is involved in activating neurons in the cerebral cortex and facilitating learning, especially perceptual learning o third system controls the functions of another part of the brain involved in learning: the hippocampus Botulinum toxin – a drug that prevents the release of acetylcholine by terminal buttons o Extremely potent poison o Very dilute solutions are used for botox Black widow spider venom – a drug that stimulates the release of acetylcholine by terminal buttons o much less toxic than botulinum toxin neostigmine – a drug that enhances the effects of acetylcholine by blocking the enzyme that destroys it nicotine – the best known drug that affects acetylcholine receptors; a drug that binds with and stimulates acetylcholine receptors, mimicking the effects of this neurotransmitter curare – a drug that binds with and blocks acetylcholine receptors, mimicking the effects of this neurotransmitter; causes paralysis o fast effects; used to paralyze patients who are to undergo surgery so that their muscles will relax completely Monoamines – a category of neurotransmitters that include dopamine, norepinephrine, and serotonin the monoamines are produced by several systems of neurons in the brain, most of which consist of a small number of cell bodies located in the brain stem, whose axons branch repeatedly and give rise to many terminal buttons distributed throughout many regions of the brain o increases or decreases the activities of particular brain functions Dopamine – a monoamine neurotransmitter involved in control of brain mechanisms of movement and reinforcement o Involved in schizophrenia, parkinson’s o Cocaine mimics dopamine reduces your own production of dopamine and when you stop the cocaine you then have withdrawal Parkinson’s Disease – a neurological disorder characterized by tremors, rigidity of limbs, poor balance, and difficulty initiating movements; caused by degeneration of system of dopaminesecreting neurons o Disorder of the basal ganglia Norepinephrine – a monoamine neurotransmitter involved in alertness and vigilance and control of REM sleep Serotonin – a monoamine neurotransmitter involved in the regulation of mood; in the control of eating, sleep, and arousal; and in the regulation of pain o A deficiency in serotonin in cerebral cortex may be responsible for alcoholism and antisocial behavior o Serotonin drugs used to treat depression, anxiety, and OCD o Prevents reuptake to prolong effects to treat disorders LSD – lysergic acid diethylamide; a hallucinogenic drug that blocks a category of serotonin receptors o Interacts with serotonergic transmission o Extremely small doses stimulate one category of serotonin receptor Peptides Neuromodulator – a substance secreted in the brain that modulates the activity of neurons that contain the appropriate receptors o as they diffuse through the brain they can activate or inhibit circuits of neurons that control a variety of functions/behaviors Peptide – a category of neurotransmitters and neuromodulators that consist of two or more amino acids, linked by peptide bonds Endogenous opioid – a neuromodulator whose action is mimicked by a natural or synthetic opiate, such as opium, morphine, or heroin o one of the best known families of peptides o reduce pain because of direct effects on the brain o decreased sensitivity to pain and persistence in ongoing behavior o people abuse opiates because they cause the release of dopamine in the brain reinforcing effect on behavior (and the effect can lead to addiction) o naloxone – a drug that binds with and blocks opioid receptors, preventing opiate drugs or endogenous opioids from exerting their effects used to help drug addicts Cannabinoids Principal active ingredient = THC which affects perception and behavior by activating receptors located on neurons in the brain THC mimics the effects of endogenous cannabinoids – chemicals produced and released in the brain & disrupts short term memory THC produces analgesia and sedation, stimulates appetite, reduces nausea caused by drugs used to treat cancer, relieves asthma attacks, decreases pressure within the eyes in patients with glaucoma, reduces the symptoms of certain motor disorders Anandamide – the most important endogenous cannabinoid Cannabinoids are found on terminal buttons that secrete glutamate, GABA, acetylcholine, dopamine, neorepinephrine, and serotonin **SEE CHART P. 101 3. The Study of the Brain o Experimental Ablation Pierre Flourens developed the method of experimental ablation and Paul Broca applied it (see Ch. 1) To study effect of experimental brain disruption on animal behavior brain lesion Brain lesion – damage to a particular region of the brain Study with animals and people with brain damage Stereotaxic apparatus – a device used to insert an electrode into a particular part of the brain for the purpose of recording electrical activity, stimulating the brain electrically, or producing localized damage (diagram page 102) Experimenters can produce electrolytic lesions by passing an electrical current through the electrode, which produces heat destroying a small portion of the brain Excitotxic lesions by injecting a chemical through the cannula that overstimulates neurons in that region around the tip and kills the neurons o Visualizing the Structure of the Brain CT Scanner – a device that uses a special xray machine and a computer to produce images of the brain that appear as slices taken parallel to the top of the skull Often called a CAT scanner (A for axial) Magnetic Resonance Imaging (MRI) – a technique with a device that uses the interaction between radio waves and a strong magnetic field to produce images of slices of the interior of the body Because different molecules take different times to recover from the magnetic force, an image can be constructed that distinguishes between different materials (gray matter, white matter, cerebrospinal fluid) Higher resolution that CT scanners Brain is passively doing something o Measuring the Brain’s Activity (waves) Microelectrode – a thin electrode made of wire or glass that can measure the electrical activity of a single neuron can be used to measure the minute electrical charges of individual action potentials Electroencephalogram (EEG) – an electrical brain potential recorded by placing electrodes on the scalp Can be used to diagnose seizure disorders or monitor stages of sleep Measures brain waves through microelectrodes Magnetoencephalography (MEG) – a method of brain study that measures the changes in magnetic fields that accompany action potentials in the cerebral cortex can be used to find brain abnormalities that produce seizures so they can be removed surgically Positron emission tomography (PET) – the use of a device that reveals the localization of a radioactive tracer in a living brain when radioactive molecules decay emit positrons (subatomic particles) inject radioactive chemical that accumulates in the brain put head under PET scanner detect positrons reveals brain regions that are most actie Functional MRI (fMRI) – a modification of the MRI procedure that permits the measurement of regional metabolism in the brain by detecting levels of oxygen in the brain’s blood vessels Brain is actively doing something o Stimulating the Brain’s Activity Transcranial magnetic stimulation (TMS) – direct stimulation of the cerebral cortex induced by magnetic fields generated outside the skull Induces electrical current in the brain tissue uses a coil of wires arranged in the shape of number 8 to stimulate neurons in the human cerebral cortex disrupts a person’s ability to detect movements in visual stimuli confirm results of lesion studies of people with brain damage Figure 4.21 on page 105 stimulator on dopamine part of the brain and it learns to press the lever for electrical stimulation of the reward center o Altering Genetics Targeted mutation – a mutated gene produced in the lab and inserted into the chromosomes of mice; abolishes the normal effects of the gene o Neural plasticity and Neurogenesis Neural Plasticity – the production of changes in the structure and functions of the nervous system, induced by environmental events Ventricular Zone – a layer of cells that line the inside of the neural tube; contains founder cells that divide and give rise to cells of the central nervous system Stem cell – an undifferentiated cell that can divide and produce any one of a variety of differentiated cells Apoptosis – death of a cell caused by a chemical signal that activates a genetic mechanism inside the cell Neurogenesis – the process responsible for the production of a new neuron Control of Behavior and the Body’s Physiological Functions Organization of the Cerebral Cortex Figure 4.24 Page 109 o Central fissure – the fissure that separates the frontal lobe from the parietal lobe o Frontal lobe – the front position of the cerebral cortex, including the prefrontal cortex and the motor cortex; damage impairs movement, planning, and flexibility in behavioral strategies o Parietal lobe – the region of the cerebral cortex behind the frontal lobe and above the temporal lobe; contains the somatosensory cortex; is involved in spatial perception and memory o Temporal lobe – the portion of the cerebral cortex below the frontal and parietal lobes; contains the auditory cortex o Occipital lobe – the rearmost portion of the cerebral cortex; contains the primary visual cortex o Regions of Primary Sensory and Motor Cortex Primary visual cortex – the region of the cerebral cortex that receives information directly from the visual system; located in the occipital lobes Primary auditory cortex – the region of the cerebral cortex that receives information directly from the auditory system; located in the temporal lobes Primary somatosensory cortex – the region of the cerebral cortex that receives information directly from the somatosensory system (touch, pressure, vibration, pain, and temperature); located in the front part of the parietal lobes Contralateral – residing in the side of the body opposite the reference point Ipsilateral – residing in the same side of the reference point Primary motor cortex – the region of the cerebral cortex that directly controls the movements of the body; located in the posterior part of the frontal lobes Chapter 5: Learning and Behavior Learning: long lasting changes in the environmental guidance of behavior as a result of experience o Emphasizes the fact that individual environments also play a role which may go against the concept of “survival of the fittest” 3 assumptions that psychologists make studying behavior: o behavior is law o behavior is controllable o control of behavior is desirable How learning is studied: o Pavlov’s Procedure Eliciting stimulus Dog present food to ticking sound when animal hears sound it would salivate and look for bowl every time o Thorndike’s Procedure Food is given after the response Chicks in maze to reach end at end rewarded with a piece of food measured the time it took for successive tries and it decreased o Pavlov’s procedure = classical procedure – conditioning procedure in which a neutral stimulus precedes an eliciting stimulus with a result that evokes a learned response resembling elicited response o Thorndike’s procedure = operant procedure – conditioning procedure in which a response (the operant) precedes an eliciting stimulus Reinforcer: an agent that reinforces a certain response to occur Primary reinforcer: effective since birth ex. food, water, etc. Secondary reinforcer: things that we know can get us a primary reinforcer money Social reinforcer: things that allow us to get recognition from others praise Punishers: the opposite of a reinforcer; causes a reaction to occur less o Temporal contiguity: relation between two events that occur close together in time time plays a factor in learning according to when eliciting stimuli are given Chapter 6: Sensation Sensory Processing (receptors – outside of the system) Sensation – the detection of simple properties of stimuli such as brightness, color, warmth, and sweetness o ex. Seeing the color blue Perception – the recognition of objects (animate and inanimate), their locations, their movements, and their backgrounds o ex. Recognizing the blue sky Transduction o Only sense receptors in brain are ones that detect local conditions like temperature & salt concentration in the blood supply o Sense organs detect stimuli such as light, sound, taste, odor, or touch Information about stimuli transmitted to brain through neural impulses (action potentials in the sensory nerves) o Transduction – the process by which the sense organs convert energy from environmental events into neural activity; each sense organ responds to a particular form of energy given off by environmental stimulus and translates that energy to neural firing so that the brain can respond o Receptor cells – specialized sensory neurons that release chemical neurotransmitters that stimulate other neurons, thus altering the rate of firing of their axons Sensory Coding o Anatomical Coding Johannes Muller formulated doctrine of specific nerve energies Sensory organs in the body send their information to the brain through different nerves Brain has no direct info about physical energy on a given sense organ anatomical coding allows brain to interpret location and type of sensory stimulus according to which incoming nerve fibers are active Sensory coding for body’s surface is anatomical o Temporal Coding Temporal coding – coding of sensory information in terms of time Rate (pattern) – by firing at a faster or slower rate according to the intensity of a stimulus, an axon communicates quantitative information to the brain o Ex. Skin sends touch/temperature/vibration/pain/stretch by certain frequencies that reflect intensity/type of touch Signals produced by a particular set of neurons (an anatomical code) tell where the body is being touched and the rate at which these neurons fire (a temporal code) tells how intense that touch is Psychophysics o Psychophysics – the systematic study of the relation between the physical characteristics of stimuli and the psychological responses (or perceptions) they produce o The Principle of the JustNoticeable Difference Ernst Weber defined the justnoticeable difference as the smallest difference between two similar stimuli that can be distinguished (aka difference threshold) Ex. Magnitude of weights being lifted Logarithmic pattern Weber fraction – the ratio between a justnoticeable difference and the magnitude of a stimulus; reasonably constant over the middle range of most stimulus intensities o Signaldetection Theory Threshold – the thin line between not perceiving and perceiving Difference threshold – the minimum detectable difference between two stimuli Absolute threshold – the minimum intensity of a stimulus that can be detected discriminated from no stimulus at all Bias with thresholds when subjects know that they are being tested signaldetection theory Signaldetection theory is an alternative method of measuring sensitivity to changes in physical stimuli that takes into account random changes in the nervous system Every stimulus event requires discrimination between a signal (the stimulus) and a noise (the combination of background stimuli and random activity of the nervous system) Takes into account our willingness to report detecting a signal (response bias) o Ex. Flash of light followed by tone Vision Light o Light consists of radiant energy similar to radio waves o Wavelength – the distance between adjacent waves of radiant energy in vision most closely associated with the perceptual dimension of hue Wavelength of visible light is relatively short (380760 nm) All other wavelengths are not visible to human eyes Entire range of wavelengths known as the electromagnetic spectrum The Eye & Its Functions o Eyes are housed in a bony socket and covered by the eyelid to keep out dust and dirt o Eyelids edged by eyelashes that keep foreign matter out of open eyes o Eyebrows prevent sweat on the forehead from dripping into eyes o Reflex mechanisms further protect the eye ex. Sudden approaches of object toward face result in eyelid closure and withdrawal of the head Cornea Sclera Iris Lens Retina Photoreceptors Optic Bipolar Cells Ganglion Cell Disk Transparen The Pigmented Lies Located on the More than 130 a a neuron in a neuron in t tissue tough muscle of beneat inner surface of million circular the retina the retina covering outer the eye h the the back of the embedded in structur the front of layer of iris eye the retina e the eye the located eye; at the the exit “white point ” of the from the eye retina of the axons of the ganglio n cells that form the optic nerve Admits Coats controls Causes image is upside Specialized all receives Receives light the eye the size of images down and flipped neurons that axons information information the pupil to be horizontally; transduce light leave from the from which focuse brain into neural the eye photoreceptors photoreceptors constricts d on compensates activity at this and passes it by means of in bright the point on to the bipolar cells, light and retina Accommodation Information and join ganglion cells, and from dilates in : changes in from the optic from which which axons dim light thickness of the photoreceptors nerve, axons proceed proceed lens of the eye is transmitted to which through the through the that focuses neurons that connect optic nerves to optic nerves to images of near or send axons s to the the brain the brain toward the brain distant objects on the retina (ciliary optic disk muscles) Performs sensory functions of the eye Contains rods and cones o nearsighted – eye is too long, image is out of focus need a concave lens to correct the focus o farsighted – eyes are too short need a convex lens to correct the focus o rods – function mainly in dim light; very sensitive to light but insensitive to differences between colors o cones – function when level of illumination is bright enough to see things clearly; responsible for color vision o fovea – small pit in the back of the retina approximately 1mm in diameter, contains only cones; responsible for most acute and detailed vision Transduction of Light by Photoreceptors o A molecule derived from vitamin A is the central ingredient in the transduction of the energy of light into neural activity o In the absence of light, this molecule attaches to a protein form a photopigment o Photopigment – a complex molecule found in photoreceptors; when struck by light, it splits apart and stimulates the membrane of the photoreceptor in which it resides Four kinds of photopigments (one for rods, 3 for cones) Rhodopsin – the photopigment contained by rods; pink Once photopigments split they become bleached Bleached photopigments = decreased sensitivity to light Adaptation to Light and Dark o Dark adaptation – the process by which the eye becomes capable of distinguishing dimly illuminated objects after going from a bright region to a dark one High levels of illumination strike the retina rate of regeneration of rhodopsin falls behind the rate of the bleaching process, so the rods are not very sensitive If you enter a dark room after being in the sunlight there are too few intact rhodopsin molecules in your eyes to respond immediately to dim light In the light you’re using cones (photopic vision) enter darkness, color goes away; use rods (scotopic vision) and it takes time for this adjustment Eye Movements o 3 types of movements: saccadic movements – the rapid movement of eyes that is used in scanning a visual scene, as opposed to the smooth pursuit movements used to follow a moving object; abrupt shifts in gaze from one point to another – eyes jump around from point to point to point about 5 jumps/second ex. Reading a line of text in a book vergence (conjugate) movements – the cooperative movement of the eyes, which ensures that the image of an object falls on identical portions of both retinas ex. Holding a finger in front of your face and bringing it closer = vergence toward nose pursuit movements – the movement of the eyes to maintain an image upon the fovea ex. Fixing gaze on a moving car Color Vision (Cones) o Light: wavelengths between 380760 mm Perceptual Dimension Physical Dimension Physical Characteristics Hue Wavelength Length of oscillation of light radiation Brightness Intensity Amount of energy of light radiation Saturation Purity Intensity of dominant wavelength relative to total light energy o The Dimensions of Color Hue – perceptual dimension of color determined by wavelength; the effect of a particular hue is caused by the mixture of lights of various wavelengths Brightness – a perceptual dimension of color determined by intensity or degree of radiant energy emitted by a visual stimulus Color of maximum brightness = vibrant; minimum = black Saturation – a perceptual dimension of color determined by purity of a color; fully saturated color consists of only one wavelength o Additive Color Mixing When two wavelengths of light are present, we see an intermediate color rather than the two components Additive color mixing – the addition of two or more lights of different wavelengths seen together as a light of an intermediate wavelength Mixing two beams of light of different wavelengths always yields a lighter color o Color Coding in the Retina Trichromatic theory – the theory that color vision is accomplished by three types of photodetectors, each of which is maximally sensitive to a different wavelength (hue) of light Thomas Young Sensitive to three colors: “pure” blue, green, and red Other psychologists later said that we perceive yellow as pure too Opponent Process – the representation of colors by the rate of firing of two types of neurons: red/green and yellow/blue Yellow/blue ganglion cells are excited by yellow light and inhibited by blue light changes the rate of firing o Negative Afterimages Negative afterimage – the image seen after a portion of the retina is exposed to an intense visual stimulus; a negative afterimage consists of colors complementary to those of the physical stimulus Ex. Staring at an image for a long time then shifting gaze to a blank wall You see the opposite colors that your retina dictates (ex. Pg 167) o Defects in Color Vision Protanopia – a form of hereditary anomalous color vision; caused by defective “red” cones in the retina red cones filled with green photopigment Deuteranopia – a form of hereditary anomalous color vision; caused by defective “green” cones in the retina green cones filled with red photopigment Trianopia – a form of hereditary anomalous color vision; caused by lack of “blue” cones in the retina lack of blue cones Audition Sound o Hertz – primary measure of the frequency of vibration of sound waves; cycles per second human ear perceives vibrations from 3020,000 Hz can vary in intensity (amplitude) and frequency variations produce changes in our perception of a sound’s loudness and it’s pitch more intense vibrations produce louder sound more rapid vibrations produce higher pitch o Timbre – a perceptual dimension of sound that corresponds to its complexity The Ear and Its Functions o Pinna – fleshcovered cartilage attached to the side of the head (what people generally refer to as the “ear”); helps funnel sound waves through the ear canal and toward the middle and inner ear o Eardrum – thin, flexible membrane that vibrates back and forth in response to sound waves and passes these vibrations on to the receptor cells in the inner ear Attached to the first set of 3 middleear bones called the ossicles o Ossicle – one of the three bones in the middle ear (the hammer, the anvil, and the stirrup) that
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