sensation & perception unit 3 chapter 4. sensation stimulation of sensory receptors and...
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SensationSensation
Stimulation of sensory receptors and Stimulation of sensory receptors and transmission of sensory info to the transmission of sensory info to the central nervous system (spinal central nervous system (spinal cord/brain)cord/brain)– Sensory receptorsSensory receptors– Stimulation automaticStimulation automatic– Presence of chemicalsPresence of chemicals
Absolute ThresholdAbsolute Threshold
WeakestWeakest amount of amount of stimulus that can stimulus that can be sensedbe sensed
Vision, hearing, Vision, hearing, smell, taste, touchsmell, taste, touch
Differ from person Differ from person to personto person– Psychological Psychological
factorsfactors– Biological factorsBiological factors
Examples of Absolute Examples of Absolute ThresholdsThresholds
Sense Absolute Threshold
VisionVision A candle flame seen at 30 miles on a dark clear A candle flame seen at 30 miles on a dark clear nightnight
HearingHearing The tick of a watch under quiet conditions at 20 The tick of a watch under quiet conditions at 20 feetfeet
TasteTaste One teaspoon of sugar in two gallons of waterOne teaspoon of sugar in two gallons of water
SmellSmell One drop of perfume diffused into entire volume of One drop of perfume diffused into entire volume of a six room apartmenta six room apartment
TouchTouch The wing of a fly falling on your cheek from a The wing of a fly falling on your cheek from a distance of 1 centimeterdistance of 1 centimeter
Difference ThresholdDifference Threshold
Minimum amount of difference detected Minimum amount of difference detected between 2 stimuli between 2 stimuli
Signal-Detection TheorySignal-Detection Theory
Method for distinguishing sensory Method for distinguishing sensory stimuli that accounts for stimuli stimuli that accounts for stimuli strengths, strengths, andand setting, your physical setting, your physical state, your mood, your attitudestate, your mood, your attitude
Also considers psychological factorsAlso considers psychological factors– MotivationMotivation– ExpectationsExpectations– LearningLearning
PerceptionPerception
Psychological process through which Psychological process through which we interpret sensory stimulationwe interpret sensory stimulation
Reflects learning, expectations, Reflects learning, expectations, attitudesattitudes
Way in which we organize our Way in which we organize our sensory informationsensory information
ClosureClosure Tendency to Tendency to
perceive a perceive a complete or whole complete or whole figure even when figure even when there are there are gapsgaps in in what your senses what your senses tell youtell you
Fill in the blanksFill in the blanks
Ground-Figure PerceptionGround-Figure Perception
Figures against a Figures against a backgroundbackground
What we perceive What we perceive as figure and what as figure and what we perceive as we perceive as background background influence our influence our perceptionperception
ProximityProximity
Group together Group together events that are events that are near each othernear each other
Things which are Things which are close togetherclose together are seen as are seen as belonging togetherbelonging together
ContinuityContinuity
Perceive things as belonging together if Perceive things as belonging together if they form some type of they form some type of continuouscontinuous pattern pattern
SimilaritySimilarity
Occurs when Occurs when objects look objects look similarsimilar to one to one anotheranother
See groups which See groups which have the have the same same characteristicscharacteristics
Common FateCommon Fate
Tendency to perceive objects that are Tendency to perceive objects that are moving together as belonging togethermoving together as belonging together
Depth PerceptionDepth Perception
Monocular CuesMonocular Cues Need only Need only one eyeone eye to to
be perceivedbe perceived Cause certain objects Cause certain objects
to appear more to appear more distant from the distant from the viewer than othersviewer than others
pictorial depth cuespictorial depth cues- -
clues about distance given clues about distance given in a flat picturein a flat picture
Binocular CuesBinocular Cues Visual cues for depth Visual cues for depth
that require the use for that require the use for both eyesboth eyes
retinal disparity-retinal disparity- images projected to images projected to different locations on different locations on right and left retinasright and left retinas
convergence-convergence- sensing the eyes sensing the eyes converging toward converging toward each other as they each other as they focus on closer objectsfocus on closer objects
Stroboscopic MotionStroboscopic Motion
illusion of movementillusion of movement rapid progression of images or rapid progression of images or
objects not moving at allobjects not moving at all our perceptionsour perceptions
fill in the gapsfill in the gaps
The Human EyeThe Human Eye
• cornea-cornea- transparent transparent tissue where light tissue where light enters the eyeenters the eye
• pupilpupil- opening in - opening in center of iris that center of iris that allows light to pass allows light to pass into the eyeinto the eye
• irisiris- controls pupil - controls pupil sizesize
• lens-lens- focuses the focuses the light rays on the light rays on the retinaretina
• retina-retina- contains contains sensory receptors sensory receptors that process visual that process visual information and information and send it to the brainsend it to the brain
• optic nerve-optic nerve- carries carries visual info to brainvisual info to brain
Near + FarNear + Far
• NearsightednessNearsightedness– Close objects are Close objects are
seen clearly but seen clearly but distant objects distant objects appear blurryappear blurry
– Eyeball is too Eyeball is too longlong
• FarsightednessFarsightedness– Distant objects seen Distant objects seen
clearly but close clearly but close objects appear objects appear blurryblurry
– Eyeball is too Eyeball is too shortshort
Rods and ConesRods and Cones
• 2 kinds of 2 kinds of photoreceptorsphotoreceptors– Neurons that are Neurons that are
sensitive to lightsensitive to light
• Rods Rods are sensitive are sensitive to only to only brightnessbrightness – Allow us to see Allow us to see
black/whiteblack/white
• ConesCones provide provide color visioncolor vision
Dark and Light AdaptationDark and Light Adaptation
• Dark-Dark- adjustment to lower lighting adjustment to lower lighting– Continues to improve for up to 45 Continues to improve for up to 45
minutesminutes
• LightLight- adjustment to bright lighting- adjustment to bright lighting– Occurs within minutesOccurs within minutes
Visual AcuityVisual Acuity
• Sharpness of Sharpness of visionvision
• Determined by Determined by ability to see ability to see visual detailsvisual details
Color VisionColor Vision
• Cones enable us to perceive colorCones enable us to perceive color– Sensitive to blue, green, redSensitive to blue, green, red
• Multi cone stimulation allows for Multi cone stimulation allows for other colors to be seenother colors to be seen– Other colors are created through Other colors are created through
combinations of red, blue, greencombinations of red, blue, green
Color ComplimentColor Compliment
• AfterimageAfterimage of a color is its of a color is its complimentary colorcomplimentary color
Color BlindnessColor Blindness• People who don’t have normal color People who don’t have normal color
visionvision
• Partially or totally unable to distinguish Partially or totally unable to distinguish colorcolor– Malfunction of conesMalfunction of cones
• Total color blindness is rareTotal color blindness is rare– Sensitive to only light and darkSensitive to only light and dark
• Partial color blindness is more commonPartial color blindness is more common– See red green but have hard time See red green but have hard time
distinguishing between the twodistinguishing between the two
Depth PerceptionDepth Perception
Monocular CuesMonocular Cues
• Need only Need only one eyeone eye to be perceivedto be perceived
• Cause certain objects Cause certain objects to appear more to appear more distant from the distant from the viewer than othersviewer than others
• Perspective, Perspective, clearness, shadowclearness, shadow
Binocular CuesBinocular Cues
• Visual cues for depth Visual cues for depth that require the use that require the use for for both eyesboth eyes
• retinal disparity- retinal disparity- depth of an objectdepth of an object
• convergence-convergence- both both eyes focus on the eyes focus on the same objectsame object
The EarThe Ear
Outer ear-Outer ear- collects collects and sends sounds to and sends sounds to the eardrumthe eardrum
Cochlea-Cochlea- transforms transforms sound vibrations to sound vibrations to auditory signalsauditory signals
Auditory nerve-Auditory nerve- transmits neural transmits neural impulses to brainimpulses to brain
DeafnessDeafness
ConductiveConductive damage to middle damage to middle
earear Affects sound Affects sound
amplificationamplification Can be corrected Can be corrected
with hearing aidswith hearing aids
SensorineuralSensorineural Damage to inner ear, Damage to inner ear,
auditory nerveauditory nerve Absence of sound Absence of sound
perception for certain perception for certain frequenciesfrequencies
““artificial ear” artificial ear”
SmellSmell
Essential to tasteEssential to taste Odors are detected by receptor neurons Odors are detected by receptor neurons
in nostrilsin nostrils React when molecules come into contact React when molecules come into contact
with themwith them Send information about odor to brain via Send information about odor to brain via
olfactory nerveolfactory nerve
Adapts quicklyAdapts quickly
TasteTaste Sweet, sour, salty, bitterSweet, sour, salty, bitter Flavor of food is more complex than tasteFlavor of food is more complex than taste
Odor, texture, temperature, tasteOdor, texture, temperature, taste
Receptors on taste buds of tongueReceptors on taste buds of tongue Sensitivity to different tastes can be Sensitivity to different tastes can be
inheritedinherited Bitter = “taste blind”Bitter = “taste blind”
Taste cells reproduce rapidlyTaste cells reproduce rapidly
https://www.youtube.com/watch?v=kyrIxAXZISc
Skin Senses (Touch)Skin Senses (Touch)
Combination of pressure, temperature, Combination of pressure, temperature, painpain Distinct sensory receptors Distinct sensory receptors Receive more than one type of sensory inputReceive more than one type of sensory input
PressurePressure Sensory receptors (pacinian corpuscle) Sensory receptors (pacinian corpuscle)
located around the roots of hair cellslocated around the roots of hair cells Fire where skin is touchedFire where skin is touched
Different parts of body more sensitiveDifferent parts of body more sensitive moremore = fingertips, lips, nose, cheeks = fingertips, lips, nose, cheeks less less = shoulders, thighs, calves= shoulders, thighs, calves
Rapidly adaptsRapidly adapts
PainPain Receptors located all Receptors located all
over bodyover body Not all equally sensitive Not all equally sensitive
to painto pain
prostaglandinsprostaglandins- help - help body transmit pain body transmit pain messages to brainmessages to brain
Can experience pain in Can experience pain in limbs no longer there = limbs no longer there = “phantom limb”“phantom limb”
Message sentto spinal cordto thalamus
in brain
Projected tocerebral cortex
where registration of
severity/locationof pain is
determined
Pain originates at the point of contact
https://www.youtube.com/watch?v=1mHIv5ToMTM
The Gate Theory of PainThe Gate Theory of PainOnly a certainOnly a certain
amount of amount of informationinformation
can be processedcan be processed by the by the
nervous system nervous system at one timeat one time
Different sensationsDifferent sensationscompete withcompete with
pain messagespain messagesfor attentionfor attention
Neurons Neurons
cant get cant get
pain messages pain messages
to brainto brain
“Flooding” preventsmany or all
messages fromgetting through
Body SensesBody Senses VestibularVestibular- position of the - position of the bodybody
sensory organs located in the earssensory organs located in the ears Enables balanceEnables balance
KinesthesisKinesthesis- position and movement of - position and movement of individual body partsindividual body parts Sensory organs in joints, tendons, musclesSensory organs in joints, tendons, muscles