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Study Guide for PSYCH-UA 1 Test 2 4.0 GPA Student
Study Guide for PSYCH-UA 1 Test 2 4.0 GPA Student

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New York University

Exam 2 Notes: Sensation, Perception, Learning and Memory (Chapters 4, 5, 7 and 8) Sensation -John Locke- 1600’s imperialist school of philosophy John Locke’s ‘tabula rasa’ (the passive perceiver) -Theory that the human mind is a blank slate at birth -We passively receive knowledge from our senses Important to review lateral inhibition! -Distal and proximal stimuli: association between what I see and how I react to get a sense of depth and size -what we learn from our senses -man and infant occupy the same stimuli at the back of the eye -Distal vs. proximal stimuli -Distal – actual object of reference, distant from observer -Proximal – representation at the sense organ, in close proximity to observer’s brain distal is a, proximal is b -man and child (distal stimulus) different heights, different distances away from proximal stimuli -Emmanuel Cont: said there must also be an innate/inherited characteristic established before your senses Pre-existing categories: conflict between innate and experienced! Associative learning: Perspective may cause different-sized distal objects to appear the same size proximally -Experience with walking towards and reaching for these objects teaches us about perspective/depth - Bishop George Berkeley is first to question how this is possible The active perceiver: -Immanuel Kant’s ‘nativism’ -Our brains biologically contain pre-existing categories for space, time and causality -Perceptual ability is dependent on these innate categories Theories of perception: Psychophysics: How do the traits of a physical stimulus relate to the subjective sensory experience they produce? -Studies input-output Psychophysiology: How do the traits of a physical stimulus affect the brain neurologically? -Studies ‘through-put’ - 1) Proximal stimulus followed by 2) neural chain of events due to transduction into electrical message, 3) psychological response (often sensory experience) Sensory Thresholds Absolute Thresholds: -Minimum input level at which stimulus is detectable -Just-noticeable-difference (j.n.d.) -Minimal amount by which a stimulus must be increased for observer to just notice a difference from the immediately preceding experience -vision -hearing -taste -smell -touch -Absolute threshold in terms of saffron – you only want just enough to flavor your dish Sensory Laws Webber’s Law -The more intense a stimulus is to begin with, the more its intensity must increase for an observer to notice a difference -Delta(I)/(I) = C : Weber’s Fraction -Constant within a modality except at great extremes -Allows for unit-less comparison of modalities -Talk about nature of constant in Weber’s Law – should be the same regardless of specific intensity (like a ratio) So what would the size of Weber’s fraction say about intensity? A high one? A low one? Large = less sensitive, small = more sensitive (think of the anvil and feather) Fechner’s Law Signal Detection Theory -effects produced by noise alone vs. effects produces by a signal plus noise -distinguishing a real event from a phantom event high sensitivity: real event of high strength low sensitivity: real events of lower strength, more overlap -real events with such low strengths may have the same curve as a phantom so you cannot tell that they are real -Two factors at work 1) Sensitivity -How well subject can perceive stimulus -How would size of Weber’s fraction correlate? 2) Response bias -Willingness of subject to answer positively or negatively when unsure -Four possible outcomes of detection experiments  Hits - report perceiving present stimulus ✓  Correct negatives – report not perceiving absent stimulus ✓  Misses (beta errors) – report not perceiving present stimulus ✗  False alarms (alpha errors) – report perceiving absent stimulus ✗ - Prozac vs. ECT – one is riskier if given to someone who doesn’t need it but more effective if the person truly does; one is less harmful if given to someone who doesn’t need it but might not really help person who truly does – analyze costs/benefits Liberal vs. Conservative Decisions (same curves) Detection Threshold -positive correlation between height and weight -regression slope (diagonal line through graph, the best way to collect data) Depression treatment: -fall below threshold, no treatment, above= treatment -paper and pencil test -Aaron Beck depression scale -serotonin reuptake blockers Depressed vs. Suicidally Depressed -depression meds are less dangerous so Drs can make more false alarms and set the criteria for decision low -suiciadally depressed meds (ECT electric current) are very unpleasant to patient and a little more dangerous so Drs don’t want to un necessarily treat patients, minimize false alarm, set criteria for decision high, increase risk of missing people who should have been treated magnitude estimation -Yohannus Muller (quality of sensation) -it is determined by nature of stimulus or how we are programmed to react to stimulus It was finally decided that it’s what nerves are stimulated and where they report in the brain that tells the quality of the stimulus! Sensory Coding: -Coding for psychological intensity -Firing frequency -A la temporal summation -Number of firing neurons -A la spatial summation -Adaptation -a.k.a. ‘habituation’ -Coding for psychological quality -Johannes Müller’s ‘doctrine of specific nerve energies’ -Differences in qualia are due to difference in activated neural structures, not differences in stimuli -Sensory code: Rules governing how sensory information is transformed from one type of signal to another -Habituation as relevant to babies, smells, etc. – how it allows you to give priority to new/surprising stimuli VISION: -Light travels in waves -Amplitude = light intensity, brightness -Wavelength = color, hue -Shorter wavelengths (nm) ≈blue, longer ≈red -Our visible spectrum = between 750 and 360 nm Eye: lets electromagnetic energy through Parts of the eye: -Iris -Circular muscle surrounding pupil -Dilates/contracts to let in more or less light -Cornea -Bends incoming light rays into focus, helps project inverted image onto light-sensitive surface (retina) -Lens -Flattens or thickens to further focus image, also projects onto retina -Choroid coat -Minimizes stray light -Light sensitive surface in eye = retina, in camera = film -Understand their similarity to the parts of a camera and how they work. Here are the similarities. Both the eye and the camera have a lens for bending light rays to project an inverted image on a light-sensitive surface at the back. In the eye a transparent outer layer, the cornea, participates in this light bending. The light-sensitive surface in the camera is the film at the back. In the eye it is the retina, also at the back, whose most sensitive region is the fovea. Both eye and camera have a focusing device; in the eye, the lens can be thickened or flattened. Both have an adjustable iris diaphragm. Finally, both are encased in black to minimize the effects of stray light; in the eye this is done by a layer of darkly pigmented tissue, the choroid coat. Retina: Contains two kinds of photoreceptors -Rods – contain rhodopsin -Located in periphery -Low visual acuity, sensitive to low light levels, motion -Approximately 120 million -Cones – 3 different types/sensitivities -Located in fovea (center of retina) -High visual acuity, sensitive to color -Approximately 6 million -Duplex Theory of Vision -We have evolved vision systems for both dim (rods) and bright light (cones) -Sensitivity of cods and rods to light The Visual Pathway: Photoreceptorsàbipolar cellsàganglion cellsàoptic nerveàLGNàcortex -Optic nerve -Place at back of the eyeball where ganglion cells exit eye: contains no rods or cones, resulting in a blind spot   -Rods and cones à bipolar cells à ganglion cells à optic nerve à V1 -Types of Ganglion cells -Parvo cells (kind-of like cones)  Particularly concentrated in the fovea  Color difference/pattern/form  Narrow-band detectors, specific -Magno cells (kind-of like rods)  Particularly concentrated in the periphery  Motion/depth perception/brightness  Broad-band detectors, holistic (Gestalt) -Parallel processing – these two types of analysis occur simultaneously Flow of visual information (left visual field and right visual field) Coding for color: -Young-Helmholtz (trichromatic) theory -3 types of cones with 3 different sensitivities -440 nm, 530 nm and 570 nm -Will respond to other wavelengths but with decreasing sensitivity as the input gets further away -Unique pattern of activation across these sensitivities for each color -Similar to how printers can create all colors out of magenta, cyan and yellow from those of peak sensitivity. The three curves that result overlap, in ways such that each wavelength along the color spectrum will effect all the three photo pigments in a unique pattern of activation. In the visual area of the brain there is a “recipe book” by which each unique patterns is translated in its own color experience psychologically. This accounts for why we can see multitudes of different hues of color by use of only three color pigments in the cones. Contrast Effects: -Brightness contrast -Stimuli look brighter on a dark background than a bright one -Edge enhancement -Exaggeration of shapes’ edges -Mach bands appear graded when actually solid This is why edges look brighter: cell C is only strongly inhibited on one side, so it sends a stronger signal to the brain than cell B (Also, cell D sends a weaker signal than cells E or F because it is STRONGLY inhibited by cell C, while cell E is only weakly inhibited due to a weaker stimulation) Lateral inhibition is relevant for Mach band illusions, edge enhancement ARE WE PASSIVE OBSERVERS? Answer = no! our perceptions are greatly affected by our own brains/neural processes Dimension of Color: -Hue -‘Color’ in its everyday sense -Varies with wavelength -Brightness -Differentiates black from white, dark from light -Only quality black and white can be distinguished on -Saturation -Color ‘purity’ – extent of chromaticity (how much gray is mixed in) The Opponent Process Theory: -Theory that output from the three cone types is recoded in antagonistic pairs by a subsequent neural mechanism -Red/green, blue/yellow, black/white -Antagonistic pairs = exciting neurons of one pair member inhibits neurons of the other -So if red/green is tipped greenwards and blue/yellow is tipped bluewards, resulting hue will be turquoise -If both systems are in balance, results in no hue -no hue = achromatic Complementary Hues: -Simultaneous color contrast -Tendency of any chromatic region in the visual field to induce a complementary color in adjoining areas -Similar effect w/ negative afterimages Color Blindness: -Highest rate among Caucasian males (about 8%) – possibly X chromosome mutation -Most are missing one of the pigments (dichromatic rather than trichromatic vision) -Possible to be colorblind without knowing it! - Could also be result of defective opponent process or brain circuitry malfunction; usually not totally unable to distinguish hues Will use color names normally, be able to distinguish at least one or two hues Perceiving Shapes: -Feature detectors -Specialized cells that respond to specific types of stimuli -Can be sensitive to relatively complex objects (a la frogs/bugs) -Receptive fields -Region of the retina a neuron is responsive to -Discovered by Hubel and Wiesel -Most recognizable forms are us piecing together smaller features The Motion-After Effect: -If upward-movement neuron becomes adapted to upward movement, it will habituate and fire less -Downward-movement detector then stops being inhibited and over-fires, causing subsequent stationary images to appear to move downward -Intraocular transfer is possible -Indicates effect must occur past retina, at point where both eyes are already integrated -Intraocular transfer = covering one eye during adaptation, you will still see the effect if you open the other eye: occurs in the brain, not at eye-level Theories of Recognition: -Transposition -The fact that we can recognize stimuli in such a variety of forms (i.e. different views, orientations, positions, depictions, occlusions, etc.) -How are we able to perceive the world in a way we can handle/use? Gestalt Psychology: -Law of similarity -We group together similar-looking objects -Law of proximity -We group together objects that are close together -Law of good continuation -We assume objects continue along their original course -Law of closure -We mentally ‘close’ incomplete figures -Studied holistic perceptions; organization is an essential feature of all mental activity, based on perceived relationships between parts of a scene -Law of good continuation sometimes results in illusory contours “subjective contours” = that triangle thing -Parsing -Separating a scene into individual objects or chunks Figure and Ground: -Objects are perceived as coherent wholes, separate from their backgrounds -Tendency to assume lighter colors are in foreground -Reversible figures -Allow for different interpretations of what is figure and what is ground -Balance of feature detectors -Cannot see both views simultaneously! -We habituate to one view until we see the other -White as foreground is detected by one kind of neuron, face detectors are another; The Necker Cube: -Look at y-intersection in bottom left to switch image; active role of perceiver in changing perception Example of pictorial
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