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Warm UpWarm Up
1. Find a group of 3 1. Find a group of 3
2.Pick up a new 2.Pick up a new notebook sheet, a notebook sheet, a discussion sheet and a discussion sheet and a ch 5 notes sheetch 5 notes sheet
Chapter 5: Sensation pt. 1Chapter 5: Sensation pt. 1
Sensation vs. PerceptionSensation vs. PerceptionSensation:Sensation: a process by which a process by which
our sensory receptors and nervous our sensory receptors and nervous system receive and represent system receive and represent stimulus energystimulus energy
Sensation is the raw data our brain Sensation is the raw data our brain takes in from the environment.takes in from the environment.
Sensation vs. PerceptionSensation vs. PerceptionPerception:Perception: a process of organizing and a process of organizing and
interpreting sensory information, interpreting sensory information, enabling us to recognize meaningful enabling us to recognize meaningful objects and events.objects and events.
Perception “makes sense” of sensation.Perception “makes sense” of sensation.Both involve one continuous process and Both involve one continuous process and
perceptual failure may occur at any level perceptual failure may occur at any level whether at the sensory level or the whether at the sensory level or the perceptual interpretation level. perceptual interpretation level.
Example:Example: ProsopagnosiaProsopagnosia
Bottom Up vs. Top Down Bottom Up vs. Top Down ProcessingProcessing
Bottom Up Processing:Bottom Up Processing: analysis that begins analysis that begins with the sense receptors and works up to the with the sense receptors and works up to the brain’s integration of sensory information.brain’s integration of sensory information.
Involves making sense of raw sensation.Involves making sense of raw sensation. Top Down Processing:Top Down Processing: Information Information
processing guided by higher-level mental processing guided by higher-level mental processesprocesses
As when we construct perceptions drawing on As when we construct perceptions drawing on our experience and expectations.our experience and expectations.
Our expectations and experiences shape how Our expectations and experiences shape how we perceive information.we perceive information.
ProsopagnosiaProsopagnosia
Is a condition…Is a condition…
Bottom Up vs. Top DownBottom Up vs. Top Down
Bottom Up Vs. Top DownBottom Up Vs. Top Down
What do you see?What do you see?
Bottom Up vs. Top DownBottom Up vs. Top Down
OLD WITCH IN PICTUREOLD WITCH IN PICTURE
When one stares at the cross for about 20 seconds or so, one first sees a gap running around the circle of lilac disks, then a green disk running around the circle of lilac disks, then a green disk running around on the grey background, the lilac disks having disappeared or having been erased by the green disk.
PsychophysicsPsychophysicsPsychophysics:Psychophysics: study of study of
the relationship between the relationship between physical characteristics of physical characteristics of stimuli and our stimuli and our psychological experience of psychological experience of themthemLightLight- brightness- brightnessSoundSound- volume- volumePressurePressure- weight- weightTasteTaste- sweetness- sweetness
Sensation: ThresholdsSensation: ThresholdsAbsolute Absolute
Threshold:Threshold: minimum minimum stimulation needed stimulation needed to detect a to detect a particular stimulus.particular stimulus.
Usually defined as Usually defined as the stimulus the stimulus needed for needed for detection 50% of detection 50% of the time.the time.
““Subliminal Messages”Subliminal Messages” Subliminal:Subliminal: information that is below one’s information that is below one’s
awareness for conscious attentionawareness for conscious attentionBelow threshold Below threshold
Some have argued that humans still “pick up” Some have argued that humans still “pick up” these messages that influence our these messages that influence our “unconscious.” Do these messages have “unconscious.” Do these messages have suggestive powers?suggestive powers?
Skeptics argue “Subliminal Messages” are Skeptics argue “Subliminal Messages” are heavily influenced by top down processes.heavily influenced by top down processes.
““Subliminal Messages”Subliminal Messages” What does the research say?What does the research say?
http://jeffmilner.com/backmasking.htmhttp://jeffmilner.com/backmasking.htm
http://www.nlpweekly.com/?p=527http://www.nlpweekly.com/?p=527
HomeworkHomework
Sensation: ThresholdsSensation: Thresholds Difference Threshold or (JND-Just Difference Threshold or (JND-Just
Noticeable Difference):Noticeable Difference): the minimum the minimum difference that a person can detect difference that a person can detect between two stimuli. What does it take between two stimuli. What does it take to tell two similar stimuli apart?to tell two similar stimuli apart?
Weber’s Law:Weber’s Law: to perceive a difference to perceive a difference between two stimuli, they must differ by between two stimuli, they must differ by a constant proportiona constant proportionlight intensity- 8%light intensity- 8%weight- 2%weight- 2%tone frequency- 0.3%tone frequency- 0.3%
Sensation: ThresholdsSensation: ThresholdsSignal Detection Theory:Signal Detection Theory: predicts predicts
how and when we detect the how and when we detect the presence of a faint stimulus (signal) presence of a faint stimulus (signal) amid background stimulation (noise)amid background stimulation (noise)
Assumes that there is no single Assumes that there is no single absolute thresholdabsolute threshold
What might a person’s detection What might a person’s detection of a stimulus depend on?of a stimulus depend on?
Sensory AdaptationSensory AdaptationSensory Adaptation:Sensory Adaptation: diminished diminished
sensitivity with constant stimulation.sensitivity with constant stimulation.
OceanOceanBad SmellBad SmellAds- cut in, zoom, fade outAds- cut in, zoom, fade out
Sensory Adaptation and Sensory Adaptation and VisionVision
Warm UpWarm Up
Get out a scrap piece of paper, find a Get out a scrap piece of paper, find a partner and come up with an partner and come up with an explanation of how we see, using at explanation of how we see, using at least 8 vocab termsleast 8 vocab terms
The Science of Energy and The Science of Energy and SensationSensation
TransductionTransduction- conversion of one form - conversion of one form of energy to another.of energy to another.
WavelengthWavelength- the distance from the - the distance from the peak of one wave to the peak of the next.peak of one wave to the peak of the next.
HueHue- dimension of color determined by - dimension of color determined by wavelength of light…color is matter of wavelength of light…color is matter of how far wavelengths are apart.how far wavelengths are apart.
IntensityIntensity- amount of energy in a wave - amount of energy in a wave determined by amplitude.determined by amplitude.brightnessbrightnessloudnessloudness
Human Vision Represents Narrow Human Vision Represents Narrow Part of All Electromagnetic EnergyPart of All Electromagnetic Energy
ROY G. BIV: Starts from longer to shorter wavelengths. R=longest; V=shortest
Vision: Physical Property of Vision: Physical Property of WavesWaves
Short wavelength=high frequency(bluish colors, high-pitched sounds)
Long wavelength=low frequency(reddish colors, low-pitched sounds)
Great amplitude(bright colors, loud sounds)
Small amplitude(dull colors, soft sounds)
Biology of Vision Step One: Biology of Vision Step One: Light Enters the EyeLight Enters the Eye
1.) Light enters the eye through the 1.) Light enters the eye through the cornea:cornea: (transparent protector) and (transparent protector) and the light passes through the the light passes through the pupil:pupil: (small opening/hole). The size of the (small opening/hole). The size of the opening (pupil) is regulated by the opening (pupil) is regulated by the iris:iris: the colored portion of your eye the colored portion of your eye that is a muscular tissue which that is a muscular tissue which widens or constricts the pupil causing widens or constricts the pupil causing either more or less light to get in.either more or less light to get in.
Biology of Vision Step Two: Biology of Vision Step Two: An Image is ProducedAn Image is Produced
2.) Behind the pupil, the 2.) Behind the pupil, the lenslens, a transparent , a transparent structure, changes its structure, changes its curvature in a process curvature in a process called called accomodation,accomodation, and focuses the light and focuses the light rays into an image on rays into an image on the light-sensitive back the light-sensitive back surface called the surface called the retina:retina: where image is where image is focuses. focuses.
Biology of Vision Step Three: Biology of Vision Step Three: Chemical Reactions and SightChemical Reactions and Sight3.) Image coming through activates 3.) Image coming through activates
photoreceptors in the retina called photoreceptors in the retina called rods and rods and cones.cones. As rods and cones set off chemical As rods and cones set off chemical reactions they form a synapse with reactions they form a synapse with bipolar bipolar cells cells which forms a synapse with which forms a synapse with ganglion ganglion cellscells which fire action potentials along the which fire action potentials along the optic nerve:optic nerve: that carries this information to that carries this information to be processed by the be processed by the ThalamusThalamus: (sensory : (sensory switchboard)switchboard) that sends information to the that sends information to the visual cortexvisual cortex which resides in the which resides in the occipital occipital lobe.lobe. The brain then constructs what you The brain then constructs what you are seeing and turns image right side up.are seeing and turns image right side up.
Parts of RetinaParts of RetinaBlind Spot:Blind Spot: part of retina where optic nerve part of retina where optic nerve
leaves the eye…no receptor cells are there. leaves the eye…no receptor cells are there. Brain fills information in with info from other Brain fills information in with info from other eye.eye.
Fovea:Fovea: central focal point of the retina, central focal point of the retina, where cones cluster.where cones cluster.
Cones:Cones: located near center of retina (fovea) located near center of retina (fovea)fine detail and color visionfine detail and color visiondaylight or well-lit conditions daylight or well-lit conditions
Rods:Rods: located near peripheral retina located near peripheral retina detect black, white and graydetect black, white and graytwilight or low lighttwilight or low light
Rods & ConesRods & ConesReceptors in the Human Eye
Cones Rods
Number
Location in retina
Sensitivity in dim light
Color sensitive? Yes
Low
Center
6 million
No
High
Periphery
120 million
Errors In VisionErrors In Vision
Acuity:Acuity: the sharpness of vision the sharpness of visionNearsightedness:Nearsightedness:
nearby objects seen more clearlynearby objects seen more clearlylens focuses image of distant lens focuses image of distant
objects in front of retinaobjects in front of retinaFarsightedness:Farsightedness:
faraway objects seen more clearlyfaraway objects seen more clearlylens focuses near objects behind lens focuses near objects behind
retinaretina
Errors in VisionErrors in Vision
NormalNormal NearsightedNearsighted Farsighted Farsighted Vision Vision Vision Vision VisionVision
Visual Involves Parallel Visual Involves Parallel ProcessingProcessing
Parallel vs. Serial:Parallel vs. Serial: parallel means parallel means simultaneous while serial means step by simultaneous while serial means step by step. Our brains process are often parallel step. Our brains process are often parallel processes while computers work serially. processes while computers work serially.
Parallel Processing:Parallel Processing: simultaneous simultaneous processing of several dimensions through processing of several dimensions through multiple pathways. Different part of brain multiple pathways. Different part of brain for:for:colorcolormotionmotionformformdepthdepth
Parallel ProcessingParallel Processing
Feature Detectors:Feature Detectors: neurons in neurons in the visual cortex respond to the visual cortex respond to specific featuresspecific featuresshapeshapeangleanglemovementmovement
How The Brain PerceivesHow The Brain Perceives
Visual Information Visual Information ProcessingProcessing
Trichromatic (three color) Trichromatic (three color) TheoryTheoryYoung and HelmholtzYoung and Helmholtzthree different retinal color three different retinal color
receptorsreceptorsredredgreengreenblueblue
Color Deficient Color Deficient SyndromeSyndrome
People who suffer red-green blindness have trouble perceiving the number within the design
Visual Information Visual Information ProcessingProcessing
Opponent-Process TheoryOpponent-Process Theory- opposing - opposing retinal processes enable color vision. retinal processes enable color vision. Example: Jesus On Title Slide.Example: Jesus On Title Slide.
““ON”ON” “OFF”“OFF”redred greengreengreen green redred blue blue yellowyellow yellowyellow blueblue black black whitewhitewhite white blackblack
Stare At This for 30 Seconds Stare At This for 30 Seconds Then Look At A White SurfaceThen Look At A White Surface