SENSATION&PERCEPTION
SENSATION
Sensation is the process through which the senses (smell,sight,taste,balance,touch and pain) pick up sensory
stimuli and transmit them to brain.
*Raw data experience
PERCEPTION
Mental process of creating meaningful patterns from raw sensory info. Together they tell us what’s happening.
NATURE OF SENSATION
The basic process: Energy stimulates a receptor cell in one of the sense organs- if the stimuli is strong
enough, the receptor cell sends a neural signal along the sensory nerves to the cerebral cortex (CNS)
Receptor cells: Specialized cells that respond to a particular type of energy. They detect &respond to one type
of sensory stimuli. (Receptor cells in eyes don’t respond to sound)
Doctrine (ilke) of specific nerve energies: One-to-one relationships btw stimuli of a specific nerve and
resulting sensory experience.
Sensory thresholds (eşik): The energy reaching a receptor must be sufficiently intense for it to have a
noticeable effect.
Absolute threshold: The minimum amount of physical energy that can be detected as stimu 50% of the time. It
marks the diff btw not being able to perceive a S and being just barely able to perceive it.
Taste-> 1 gram of table salt in 500 liters
Smell-> 1 drop of perfum diffused through three-room apartment
Touch-> Wing of bee falling on your check from 1cm
Hearing-> The tick of watch from 6 meters in very quiet conditions
Vision-> a candle flame seen from 50km on a clear dark night
Sensory thresholds
Difference threshold: Smallest change in stimuli that can be detected 50% of the time. Measure of the smallest
increase or decrease in physical S that is required to produce notable diff. AKA just noticeable diff.
Sensory adaptation: Adjustment of the senses to the level of stimuli they are receiving. Occurs when the
sensory receptors grow accustomed to constant, unchanging levels of stimuli (sound, sight, smell) so we notice
them less or not at all. (Smokers become accustomed to smell of cigarette on their clothing)
Subliminal perception
Certain events in the outside world occur outside our conscious awareness. We may respond that are below our
level of awareness or below the threshold of conscious awareness. The effect only occurs in lab studies. No
significant effect of subliminal info outside of labs.
Extrasensory Perception
A response to an unknown event not presented to any known sense. Refers to extraordinary perception such as:
Clairvoyance- awareness of an unknown object or event
Telepathy- knowledge of someone else’s thoughts or feelings
Precognition- knowledge of future events
Cornea: Transparent protective coating over the front of the eye. Light enters
VISION
the eye through cornea. Bends the light rays inward.
Pupil: Light then passes pupil. Small, dark opening in the iris.
Iris: Colored part of the eye. Bright light – muscles in iris contract to make the
pupil smaller, protects eye and help us see well in bright light. Dim light –
muscles relax to open the pupil wider& let in as much as light as possible.
Lens: Focuses light onto the retina. Changes shape to focus on objects that are
closer or farther away. Flattens as it focuses on objects at a distance. Becomes
more spherical as focuses on close objects.
Retina: Lining of the eye containing receptor cells that are sensitive to light.
The image projected onto retina is upside down and reversed left to right.
Fovea: On the retina, directly behind lens, lies a depressed spot. Occupies the
center of the visual field. Provides clearest and sharpest area of vision in the
whole retina. When you look directly at an object, the image of the object is
focused on the center of your fovea.
Blind spot: Spot on the retina, where the optic nerves leave the eye for the
brain. Has no receptor cells.
Receptor Cells: Cells in the retina that are sensitive to light. Visual receptors are called rods and cones.
Cones: light sensitive receptor cells that enable us to see color and fine detail in adequate light, but they don’t
function in very dim light. About 8 million. Respond to color and light and dark. Work best in bright light.
Found mainly in the fovea.
Rods: extremely light sensitive cells, allowing eye to respond to very low levels of light. About 120 million.
Respond to light and dark. Very sensitive to light- responsible for night vision. None in fovea.
Bipolar cells: Receive input from receptor cells(rodes&cones) The one-to-one connection btw cones and bipolar
cells in the fovea- allows for maximum visiual acuity- the ability to visually distinguish fine details.
Ganglion cells: Receive input from bipolar cells. Blind spot is where axons of ganglion leave the eye.
Adaptation is the process by which our senses adjust to diff levels of stimuli. In visual adaptation sensitivity of
rods and cones changes according to how much light is available. Dark adaptation is increased sensitivity of rods
and cones in darkness. Movie theatre-> Your cones can’t function due to their high threshold. Rods don’t
function because they had been knocked out previously after 7 minutes rods regenerate themselves and they
make you see your bystanders. Light adaptation is decreased sensitivity of rods and cones in bright light. Under
bright sunlight-> your rods cannot function because they had been knocked out previously, few minutes later
cones regenerate themselves and you see. Afterimage sense experience that occurs even after the visual stimulus
has been removed. Consequences of adaptation.
From eye to brain
The brain is responsible for converting the upside-down retinal images into meaningful visual info. The rods and
cones change light waves into neural impulses that are fed to the bipolar cells., which in turn pass the impulses
along the ganglion cells. Axons of ganglion cells leave the eye from blind spot, there are no rods or cones at this
point.
Rods and cones -> bipolar cells -> ganglion cells -> optic nerve
Optic nerve carries neural messages from each retina to both sides
of the brain.
Optic chiasm: two optic nerves come together at the optic chiasm,
the point where part of each optic nerve crosses to the other side of
the brain. The nerve fibers from the right half of each retina go to
RH, those from the left half of each retina go to LH. Imp. bec. It
allows visual info from single eye to be represented in the primary
visual cortex of both hemispheres. Imp. for depth perception too.
Color vision: Dimensions of color
1. Hue (wavelength in physics)- refers to colors such as red, blue or yellow- if you turn around the base,
you change the wavelength values.
2. Saturation (purity in physics)- refers to the vividness of hue, purity of a color- the distance from the
center determines the saturation- surface has max. saturation.
3. Brightness (intensity in physics) – the nearness of a color to white- the higher you go, the higher the
intensity.
Theories of Color Vision
1. Color Mixing: Additive color mixing-> Mixing of lights of diff hues(blue light+ yellow light=
green light) Subtractive color mixing-> Mixing pigments (paints- chemical) Whenever you
mix two colors, you lose the saturation. Complementary colors- colors which result in gray
when we mix them in equal amounts (red+ green= gray)
2. Trichromatic theory: Three diff types of cones in retina that are red cones, greed cones, blueviolent cones. They are 3 primary colors- all other colors can be produced by these colors.
Experience of color is the result of mixing of the signals from these receptors. Can account for
some types of colorblindness. Colorblindness: %7 of men %1 of women- partial or total
inability to distinguish certain colors from one another. Trichromat: normal vision. Dichromat:
blind to either red-green or blue-yellow Monochromat: no color at all only shades of light and
dark. This theory cannot explain all aspects of color vision. Color afterimages?
3. Opponent-Process Theory: Three pairs of color receptors-Yellowblue pairs, redgreen pairs,
blackwhite pairs. Three kinds of cells respond by increasing or decreasing their rate of firing
when diff colors are present. (The red/green cells increase their firing rate when red is present
decrase when green is present.) Members of each pair work in opposition. Can explain color
afterimages. If you look at enough at one color in the opponent process pair and then look at a
white surface, your brain will give you the sensation of the opposite color- a negative
afterimage, a visual sensation that remains after the stimulus is withdrawn. After you have
started at one color in opponent process pair, the cell responding to that color tires and the
opponent cell begins to fire, producing the afterimage.
Color vision in other species
Other species see colors diff than humans. Primates are trichromats, most other mammals are dichromats.
Rodents tend to be monochromats, as are owls who have only rods. Bees can see ultraviolet light.
HEARING
Sound is psy. experience created by the brain in response to changes in air pressure that are received by the
auditory sys. Pressure waves in the air. Sound waves changes in pressure caused by molecules of air moving.
Frequency-> Number of cycles per second in a wave. Measured by Hertz (Hz). Determines pitch of the sound
(how high or low the tone is) The higher frequency the higher the tone of the sound. The human ear responds to
frequencies from 20 Hz to 20.000 Hz.
Amplitude-> Magnitude(height) of sound wave. Determines loudness (soft vs. loud) Measures in decibels (dB)
Prolonged exposure to sounds above 85 decibels can cause permanent damage to the ears.
Outer ear: visible part of the ear: pinna & auditory canal
Pinna-> collects the sound waves, reflects the sound of the auditory canal.
Eardrum (Tympanic Membrane) (Kulak zarı)-> Thin, flexible membrane.
Hearing begins when sound waves strike the eardrum and cause it to vibrate.
Middle ear: contains three small bones: hammer, anvil, stirrup. They are
attached to the eardrum from behind. The sound waves are automatically
transferred to these bones from tympanic membrane by vibrating. They
connect the eardrum to the oval window and amplify the sound waves.
Inner ear: begins at the inner side of the oval window. Contains cochlea,
vestibular sacs, semicircular canals.
Oval window: Membrane btw middle and inner ear. It’s the opening into the
cochlea.
Cochlea: Fluid filled, snail shaped, bony chamber that contains basilar
membrane and hair cells (sound receptors) When the stirrup pushes against
the oval window, it sets up vibrations to move the fluid in the cochlea back
and forth in waves. Inside the cochlea, attached to its thin basillar membrane
are about 15.000 sensory receptors called hair cells each with a bundle of
hairs protruding from it. Tiny hair bundles pushed and pulled by the motion
of fluid inside cochlea. Movement is translated into an electrical impulse,
which is transmitted to the brain by auditory nerve.
Basilar membrane: Membrane in cochlea with hair cells. When the fluid
begins to move, basilar membrane ripple in response.
Auditory nerve: Connection from ear to brain.
Theories of hearing
Place Theory (Helmholtz): Pitch is determined
By the brain by nothing place of vibration along
The basilar membrane that vibrates most.
Low frequencies are coded at the far of the basilar
Medium and high frequencies at the close b.m
Diff. locations on b.m vibrate in response to diff pitched sounds.
Frequency Theory: Pitch is determined by the brain by frequencies that hair cells produce action potentials
across basilar membrane. Hair cells vibrate same number of times per second as the sounds reach them.
Hearing loss: Any of several structures could be disrupted. Many of them treatable or entirely preventable. Can
be caused by: injurt, infections, explosions, long term exposure to loud noises.
LEARNING
The process by which practice or experience results in a relatively permanent change in behavior or potential
behavior.
*Behaviorism is a school of psychology w/ 3 assumptions:
1-) Even most complicated learning process can be reduced to simpler associations (reductionism) It’s against
Gestalt psychology.
2-) Learning process is general across species, we all learn in the same way.
3-) External events should be focused rather than internal ones because external events are objective. Memory
is a black box.
Classical Conditioning is learning in which a response caused by one stimulus comes to elicited by a
different, formerly neutral stimulus. Ivan Pavlov discovered it. His experiments on salivation in dogs turned
into research on learning. He has Nobel prize for physiology of digestive system.
Food deprived dog harnessed in apparatus then a tone was sounded followed by meat powder being placed in
hungry dog’s mouth. Then, it causes dog to salivate. Dog’s salivation to meet powder is unconditional reflex
(unconditional response). Later on, the dog shows responsiveness to the tone. Over time, dog comes to salivate
at the sounding of the tone alone. When this occurs, Pavlovian conditioning has occurred, conditional
(conditioned response) reflex has developed.
1. Unconditioned stimulus (US) automatically causes a specific response in an organism. (Food)
2. Unconditioned response (UR) is automatic and unlearned. (Salivation in response to food)
3. Conditioned stimulus (CS) is formerly neutral stimulus that is paired w/ US and causes desired response
all by itself. (Bell in Pavlov’s studies.)
4. Conditioned response (CR) the learned response to CS. (Salivation in response to bell)
Before Conditioning
Bell (NS) -> No Response
Food (US) -> Salivation (UR)
During Conditioning
Bell (NS) -> Food (US) -> Salivation (UR)
After Conditioning
Bell(CS) -> Salivation (CR)
Intermittent pairing means pairing the conditioned stimulus and unconditioned stimulus on only a portion of
the learning trails. It reduces both the rate of learning and the final strength of the learned response.
Humans can also learn to associate certain sights or sounds w/ other stimuli. Many phobias are the result of
classical conditioning. The “Little Albert” experiment (John Watson and Rosalie Rayner) demonstrated a
classically conditioned phobia. They conditioned him to fear white rats by making a loud noise every time the
boy was shown a rat.
A technique that uses classical conditioning to treat phobias (Mary Cover Jones)- a method for unlearning
fears. Rat= candy. This method evolved into desensitization therapy (Wolpe), a conditioning technique designed
to reduce anxiety about a object or situation. Recently, it’s discovered that immune system may respond to CC
techniques.
*Classical conditioning is selective. Preparedness (Seligman) is the notion that humans are predisposed to
develop certain phobias because they have survival value. Contrapreparedness or taste aversion-> Eating food=
becoming ill. Learned association btw. taste of a food and feeling revulsion.
Exposure Therapy: Elevator, Psychoneuroimmunology: Immune system fights against our tissues->Autoimmune
disorder: Lupus
Operant (Instrumental) Conditioning concerns the learning behavior that operates the environment:
The person or animal behaves in a particular way to gain something desired or avoid something unpleasant
whereas classical conditioning focuses on a behavior that invariably follows a particular event. Learning in
which organism’s behavior is followed by reward or punishment. It’s emitted rather than elicited. Process of OC
can be speed up by : increase motivation, reducing opportunities for irrelevant responses, or shaping. Skinner
Box (B.F. Skinner) is a small cage w/ solid walls that is empty except for a food cup and activating device, such
as button (pigeon experiment=supersitious). In this environment, it doesn’t take long for an animal to press the
button that releases food into cup. Shaping is reinforcing successive approximations of the desired behavior.
(Tiger jumping through hoop- first pedestal, then pedestal to another finally hoop that is on fire)
 Thorndike’s Research: He was the first researcher to study operant behavior systematically, he used
a “puzzle box” to determine how cats learn. A cat is placed in a “puzzle-box”. The door of the box is
held fast by simple latch. Just outside the cage is a piece of fish on dish. When cat sees the fish, move
nearest to the part closest to it and try to escape. When it couldn’t escape, it starts to move around the
cage and after few minutes it bumps against the latch and the door opens. When it’s repeated, cat
develops a quick & efficient series of movements for opening the latch. Speed of correct response
increases over trials.
Law of Effect (Thorndike)- principle of reinforcements: Responses which are followed by a satisfying
state of affairs (reinforcement) would occur w/ greater frequency over time. On the other hand, responses which
are followed by annoying state of affairs (punishment) would occur less frequently over time.
Thorndike’s experiments illustrate two factors that are essential in operant conditioning: Operant response (CO
occurs when operant response operates on the environments to produce specific consequences. By pawing at the
latch (o.r) the cat was able to open the door) and Consequence (follows the behavior, by opening the door, cat
gained freedom or fish. Reinforcement& Punishers)
Reinforcer is a stimulus that follows a behavior and makes that behavior more likely to occur again. It always
strengthens behavior.
*Negative Reinforcer (-)
*Positive Reinforcer (+)
Removes sth. unpleasant from the environment
Adds sth. rewarding following a behavior,
following a behavior, making that behavior more
making that behavior more likely to occur again.
likely to occur again.
Giving a dog a treat for fetching a ball
Taking an aspirin to relieve a headache
Goal of punishment is to decrease the occurrence of a behavior. Effective punishment should occur as soon as
possible after the behavior, should be sufficient, certain, consistent.
*Punishment is not effective as reinforcement. It doesn’t teach proper behavior, only suppresses undesirable
behavior. Avoidance training is an alternative strategy, involves learning a desirable behavior that prevents and
unpleasant condition such as punishment from occurring. Active avoidance: taking specific action to prevent
aversive (itici) S. Passive avoidance: refraining (geri durmak) from an action to prevent aversive S.
Operant conditioning is selective. Its techniques work best w/
behaviors that would occur in a specific situation. Pigeon can
pecking but not dancing.
Tendency to repeat behavior that are followed closely by a
reinforcer, even if they are not related is superstitious
behavior. Pair of socks can be considered lucky.
Learned Helplessness means failure to avoid or escape from an unpleasant or aversive stimulus that occurs as
a result of previous exposure to unavoidable painful stimuli. In Seligman’s experiment, instead of pairing the
tone w/ food he paired it w/ harmless shock, restraining the dog in hammock during the learning phase. Then
they put the conditioned dog into a shuttle box, which consists of a low fence so that dog can easily jump over.
However, when the bell rang, nothing happened. What conditioned dog learned in the hammock, was that trying
to escape from the shocks is futile. The dog is learned to be helpless. Depressed people become that way because
they learned to be helpless. They learned that whatever they did, is futile and they have no control.
Biofeedback is an operant technique that teaches people to gain voluntary control over bodily processes like
heart rate, muscle contractions. It shapes behavioral change. When used to monitor and control brain activity it is
called neurofeedback.
CLASSICAL VS. OPERANT CONDITIONING
 Response Acquisition
*In classical conditioning, naturally occurring responses are attached to conditioned stimulus by pairing that
stimulus w/ unconditioned stimulus. Spacing of trials effects rate of training -intermittent pairing reduces both
rate of learning and final level of learning achieved.
*In operant conditioning Skinner Box if often used to limit the range of responses and increase the likelihood
that the desired response will occur. Letting animal become hungry can speed up. Shaping, reinforcing
successive approximations to target behavior, can speed up acquisition.
 Extinction and Spontaneous Recovery
*In CS, when US and CS are no longer paired- extinction – the strength or frequency of learned response
diminishes. When Pavlov’s dogs received no food after repeatedly hearing the bell, they ceased to salivate at the
sound of the bell. Spontaneous recovery occurs when the CR temporarily returns without additional training.
*In OC, extinction occurs when reinforcement is stopped. Spontaneous recovery occurs when behavior
temporarily returns without additional training.
 Generalization and Discrimination
*In classical conditioning-> Stimulus generalization: Transfer of learned response to diff but similar stimuli
(Albert’s generalized fear of all kind of white, furry objects)
Stimulus discrimination: Giving response that is somewhat diff from the response originally learned to that
stimulus. (If Albert had only feared of rat)
*In operant conditioning-> Response generalization: Tek stimuli, benzer davranış. Ödev yapması karşılığında
şeker alan birinin ödev dışında yatağını çantasını toplaması gibi davranışlar.
Response discrimination: Only specific responses are reinforced in the presence of specific stimuli. Farklı
uyaran, farklı davranış. Hamburgeri normalde elle yiyen birinin bir Fransız restorantında çatal bıçakla yemesi.
 New Learning Based on Original Learning
In both classical and operant conditioning, original learning serves as a building block for new learning.
*Higher-Order Conditioning in Classical Conditioning: New conditioning based on earlier conditioning. Earlier
CS is used as US for further training. (Pavlov used the bell to condition his dogs to salivate at the sight of a black
square. It’s difficult due to extinction unless the first US is presented occasionally, the initial conditioned
response will be extinguished.)
*Secondary reinforces in operant conditioning: In OC, neutral stimuli can become reinforcers by being paired or
associated w/ other reinforces. Primary reinforcer: Intrinsically rewarding- reinforcement rewarding of itself like
food and water. Secondary reinforcers: Acquire rewarding properties by being associated w/ primary reinforcersvalue is learned through association. Money would be example. Token economy refers to a reward system used
in a behavior modification programs. (Child earning sticker as a reward for completing a chore)
 Contingencies (Olumsallık)
“If-then” relationship btw conditioned and unconditioned stimuli in classical conditioning or btw responses
& reinforces in operant conditioning is called a contingency. (If you do your homework, you’ll get candy)
Schedules of Reinforcement: Continuous vs. Intermittent
Continuous is not practical or effective because it means
reinforcing all the time.
Intermittent schedules: Interval vs. Ratio
Interval-> passing of time (15th December of month=salary)
Ratio-> number of responses made (5 chair= salary)
**Classical conditioning is passive whereas operant conditioning requires active participation. In OC, reinforces
act as incentives (teşvik) for learning. CC does not provide incentives.
Cognitive Learning is learning that depends on mental activity that is not directly observable. (Attention,
expectation, thinking, memory)
Latent learning (Tolman) maintains that subjects store up knowledge even if this knowledge is not reflected in
their current behavior because it is not elicited by reinforcers. (Rat + Maze experiment) Latent learning is stored
as mental image, or cognitive map.
Insight & Learning Sets: Insight learning is also called “A-ha! Experience” (Köhler) because that is what many
people say when insight arrives. (Banana + chimpanzee + stick)
Learning sets refer to increasing effectiveness at problem solving through experience (trial + error) (Harlow’s
Experiment) Learn how to learn.
Learning by Observing: It occurs when we see the consequences of other people’s behavior. Social learning
theory-> Albert Bandura says that reinforcement is unrelated to learning itself, but it may influence whether
behavior is actually displayed. Bobo doll experiments-Human aggression. 3 diff ending, 3 diff attitude.
First group-> child is praised so watchers displayed most imitative behavior.
Second group-> child is told to sit in corner, so watchers displayed least imitative behavior.
Third group-> child went out, so watchers are in between first and second group.
Bandura argued cartoon characters’ aggression influence more than adults on children.
Bandura’s four-step pattern:
1-Attention: one notices sth. on environment.
2-Retention: one remembers what was noticed.
3-Reproduction: one produces an action that is a copy of what was noticed.
4-Motivation: environment delivers a consequence (reinforcement and punishment)
Observation learned behaviors can be affected by vicarious reinforcement and vicarious punishment- affects
willingness of others to perform behaviors they learned by observing those models. (What happens to people we
are watching?)