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Psychology 1 1
PerceptionPerception - is a collection of all the
processes or channels for gaining information about the world around us and our place in the world (physical location)
That is, all senses (sight, sound, touch, etc.,)Crucial for survival and effective behaviorIs an ACTIVE process
– Actively searching for info– Actively constructing internal representation
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Understanding perception is harder than perceiving– Perceptual Mechanism (touch eye socket demo)– How perception occurs and how we get a
representation of the world. (why we make perceptual mistakes)
Need different types of knowledge to do so– Basic Anatomy & Physiology– Psychophysics– Patterns of Stimulation (effect on Perception.)– Physiological Mechanisms underlying Perception.
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Basic Anatomy & Physiology
Nervous system in general
Sensory systems in particular
Will emphasize human systems
• (particularly vision and audition)
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. Psychophysics
How much light? How much sound?
Intensity vs. Brightness
How well do we adapt?
What are the limits of the senses?
Psycho – the world of EXPERIENCE
Physical – the world of REALITY&
Psychophysical Methods
• Concerns the relationship between:
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. Subjective ContoursCan you PERCEIVE a triangle?
Can you CONCEIVE of a triangle?
There is a difference between perception and cognition
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Connections?Different occupations with various demands fit to
the content of this course– Air Traffic Controller (safe path)– Radiology (normal or abnormal)– Food Manufacturer ( Crunchy Munchy)
What does all this have in common?
Psychophysics
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Psychophysics
Looks at the relationships and study the relationships between the physical and perceptual world– That is, Experience and Physical reality
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Measuring PerceptionDetection “problem” – Is there something there.
How bright before someone know it is there.
Discrimination – How do you tell a difference. Are these two different?
Scaling – Change in Physical and Change in Experience. Not quantitatively equal in change between perceptual and physical
Recognition or identification – how do you identify or recognized what you’ve seen before.
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– Sclera; white membrane– Cornea; focuses light– Iris; muscles behind cornea– Pupil; opening at center of iris– Lens; focuses light– Retina; cones and rods– Pigmented Choroid; small blood vessels
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– Optic disk; blind spot– Optic nerve; contains ganglion cell fibers– Vitreous Humor; jelly like substance – Aqueous Humor; nourish eye– Ciliary Muscles; connects to Zonule fibers– Zonule fibers; mesh-like sac around lens– Canals of Schlemm; “drain”
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Problems with the Eye– Glaucoma; blockage at Canals of Schlemm, increase
in intraocular eye pressure.• Open angle – rapid onset, notice earlier, change occurs
over a period of hours. 10% of Glaucoma cases.
• Closed Angle – gradual onset, clogged up gradually and not easy to notice with few symptoms. 90% of Glaucoma cases.
• Check up should be done past 30 years old at a regular basis.
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Glaucoma cont’– Remedy may be in the form of eye drops to balance
pressure.– Laser surgery to open canals of schlemm but only if
caught at the early stages.
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Cross section of Retina (less than 1mm thick) “inverted retina” -all mammals.
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ReceptorsRods
– rod shaped– Peripheral (none in fovea) – Many rods : bipolar cells– Black and white, night/dim light
Cones– Cone shaped– Centrally located– One cone: one bipolar cell– Color– daylight
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Muscle System
Intraocular– Iris & Ciliary
Extraocular– Three Pairs
Cyclotorsional– 10-20 degrees
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Eye Movement
Fixation– Eyes directed at a point
Focus– Have image on the back of eye
• Vergence; changes for different distances
Version– Left & Right; same direction at same time
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Eye Movement cont’
Saccadic vs. Pursuit– Saccadic
• Rapid/ sudden change in refixation
• 1/10 of a sec.
– Pursuit• Slower and smoother
• “tracking”
• Requires target
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Focusing on an image
Cornea & Lens– Accommodation; change focus
• Only lens contributes to focusing of objects
• Far object; ciliary muscles relax, lens less power, lens less curved
• Near object; ciliary muscles contract, lens more power, lens more curved
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Problems with clarityMyopia
– Nearsightedness; eyeball is too long, need minus lens to reduce focusing power
Hyperopia– Farsightedness; eyeball is too short, need positive
lens to increase focusing power
Presbyopia– Old eye, lens hardened, lost of accommodation
(reduction in range)• Bifocals & multifocals
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Surgery for eyeRK; Radial Keratonomy (cut into cornea to
collapse and make flatter)
PRK; Photo Refractive Keratectomy (Remove part of cornea)
LASIK; (“flap & zap”) early recovery period
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Surgery for eye cont’Cataracts; interferes with ray of light entering into
eye, glares and blurs.– Rid natural lens of eye– Replace loss power
• Strong glasses or• Contact lens or• INTRAOCULAR IMPLANTS (artificial lens inserted into
eye)
Astigmatism; uneven curvature of the cornea– Weighted contacts
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Color Vision
Three sorts of necessary background– Physiological Basis– Color Mixtures– Describing color experiences
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Physiological Basis
3 Different Photopigments– Cyanolabe = blue cones– Chlorolabe = green cones– Erythrolabe = red cones
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Color Vision Defects can be Inherited
Problems– Sex-linked recessive (x-chrom.)– # men > # women
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Color Vision Defects can be AcquiredSubject to change, progressionAging
– lenses yellow
Disease– Diabetes– Glaucoma
Medications– Antihistamines– Diuretics– Some antibiotics
Other Drugs– Alcohol– Marijuana
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Audition
2nd most important sensory system for humans.
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Two definitions of “sound”– Physical definition - sound is pressure changes in the
air or other medium
– Perceptual definition - sound is the experience we have when we hear
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Propagations in changes of pressure– i.e., ripples in a pond
344 m/sec “Speed of Sound”
Affects Speed of Sound– Temperature– Density– humidity
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Outer ear - pinna and auditory canal
– Pinna helps with sound location
– Auditory canal - tube-like 3 cm long structure
• Protects the tympanic membrane at the end of the canal
• Resonant frequency of the canal amplifies frequencies between 2,000 and 5,000 Hz
• Capture, funnel sound, localize, amplify
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Middle ear
2 cubic centimeter cavity separating inner from outer ear
It contains the three ossicles
– Malleus - moves due to the vibration of the tympanic membrane
– Incus - transmits vibrations of malleus
– Stapes - transmit vibrations of incus to the inner ear via the oval window of the cochlea
Connection/ transformation/ equalize pressure
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Inner ear
Main structure is the cochlea
– Fluid-filled snail-like structure set into vibration by the stapes
– Divided into the scala vestibuli and scala tympani by the cochlear partition
– Cochlear partition extends from the base (stapes end) to the apex (far end)
– Vestibular System - Balance
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Ototoxic Drugs
Aspirin
Quinine
Streptomycin
Loop inhibiting diuretic
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Noise Induced Hearing Loss
Not related to presbycusia
“4k” dip indicator of NIHL
Accelerate over the years
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Hearing Protection Devices
Passive Devices– Blocks sound entering ear
Ear muffs– Need a good seal
Ear plugs– Premolded – User molded (foam)
