PSYCH 4R03 Lecture Notes - Homeostasis, Relative Pitch, Autonomic Nervous System

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25 Jan 2013
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Chapter 5: Learning and Behaviour
Habituation:
we react automatically to events:
orienting response – organism directs appropriate sensory organ toward
source of novel stimulus
habituation – simplest form of learning: learning not to respond to an
unimportant event that occurs repeatedly
George Humphrey – experiment with snails, got used to tapping so wouldnt
retreat into shell
from evolutionary perspective – waste of time and energy
Wicks and Rankin – used worm Nemoda and subjected them to taps or heat
found that this withdrawing effect occurs through neurons that respond to
mechanical stimulus, regardless of stimulus
could produce habituation to tap-elicited stimulus but not to heat – shows
they learned something about tap and could distinguish it from reaction to
source of heat
only had 302 neurons in NS
short term habituation – simplest form
long term habituation animals with more complex nervous system
pattern of experience plays a role in distinguishing long-term and short-term:
when sitmuli are massed into quick repetitions, habituation is rapid but ST
when sitmuli are presented in small groups that are spaced over time,
habituation is slower but LT
evidence that 2 different neural mechanisms are responsible for this
Classical Conditioning:
invovled learning about conditions that predict that a significant event will
occur
Pavlov – noticed dogs salivated when they saw research assistant come into
room so he set up experiment with bell and food and dogs learned to salivate
when they heard bell ring
Classical Conditioning – process by which a response normally elicitied by
one stimulus (UCS) comes to be controlled by another stimulus (CS) as well
sequence and timing is important
unconditional stimulus – stimulus that naturally elicits a reflexive response
unconditional response - behaviour itself that is naturally elicited by UCS
conditional stimulus – stimulus that, because of repeated association with
UCS, eventually elicits conditional response
conditional response – response elicited by CR
Biological Significance of Classical Conditioning:
two funcitons:
ability to learn to recognize stimuli that predicts occurence of an important
event allows learner to make appropriate response faster and more
effectively
siamese fighting fish more likely to win fight if they were given stimulus
(CS) that intruding male (UCS) would enter territory
blue gouramis more likely to mate sooner and produce more offspring
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when they received stimulus (CS) signalling approaching female (UCS)
learning that occurs with biologically significant UCS is more resistant to
subsequent modifications
stimuli that were previously unimportant acquire some properties of
important stimuli with which they have been associated and thus become
able to modify behaviour
neutral stimulus becomes desirable when it is associated with desirable
stimulus or becomes undesirable when it is associated with undesirable
stimulus
specific properties of UCS become associated with CS - UCS takes on
symbolic value
Ward-Robinson – demonstrated this with pigeons where they pecked at
light when sound went on (paired sound CS with food UCS)
adaptive significance is so general that even nematode exhibits it
Wen – placed worms in solution of Na+ or Cl- with bacteria; when placed with
patches on ions and no bacteria, worm migrated to ions thinking there was
food
Basic Principles of Classical Conditioning:
discovered 7 interesting phenomena: acquisition, extinction, spontaneous
recovery, stimulus generalization, and discrimination
Acquisition:
acquisition – time during wich CR appears and increases in frequency
strength of CR is influenced by: intesity of UCS and timing of CS and UCS
more intense UCS produces rapid learning
more intense UCS stronger the CR is
classical conditioning occurs fastest when CS occurs shorlty before UCS and
both end at same time
0.5 seconds is optimal delay between onset of CS and UCS
little conditioning if CS follows UCS, or if too long or short delay will be
slower and weaker
Extinction and Spontaneous Recovery:
extinction – elimination of a response that occurs when CS is repeatedly
presented without being followed by UCS
participant learns that CS is no longer followed by UCS – if neither are
presented then extinction doesn't occur
doesn't necessarily disappear permanently
spontaneous recovery – after an interval of time, reappearance of response
that had previously extinguished
Stimulus Generalization and Discrimination:
generalization – CR elicited by stimuli that resembles CS used in training
once response has been conditioned to CS similar stimuli will also elicit that
response
more stimuli resembles CS more likely it will elicit CR
discrimination – appearance of CR when one stimulus is presented (CR+) but
not another one (CR-) accomplished by using 2 CS during training – one is
followed by the UCS and another isn't
involes learning difference between 2 or more stimuli
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Conditioned Emotional Responses:
many stimuli are able to arouse emotional response (disgust, contempt, fear,
anger, sadness, tenderness, longing, or sexual desire)
many had no special signifance but were paired with stimuli that elicited strong
emotional reaction so they acquired emotional or evaluative signifance
Todrank, Byrnes, Wrzesniewski, and Rozin – people associated pleasant
or unpleasant odour with attractive or unactriveness of person in photograph
phobias – unreasonable fear of specific onjects or situations learned through
classical learning
at some time early in life person was exposed to now-fearsome object in
conjunction with stimulus that elicited pain or fear
classical conditioning can occur without direct experience with CS or UCS –
can be learned through observation (vicariously)
imaginary episodes that we picture as we hear or read story (UCS) can
provide imaginary stimuli (CS) that lead to real conditional emotional
responses (CR)
therapists use knowledge of principles of learning to eliminate them
suggestions that biologically relevant stimuli are especially prone to
classically conditioned emotional responses
What is learned in Classical Conditioning:
research shows that for classical conditioning to occur, CS must be reliable
predictor of UCS
neutral stimulus becomes a CS only when following conditions are satisfied:
CS regularly occurs prior to presentation of UCS
CS does not regularly occur when UCS is absent
principle has been clearly established by conditioning phenomenon known as
blocking
blocking – prevention of or attenuation in learning that occurs to a neutral CS
when it is conditioned in presence of a previously conditioned stimulus
CSA is paired with UCS, then new CSB is presented together with CSA and
compound of 2 stimuli is followed by UCS; compared to condition where CSA
has not been previously trained, CSB acquires little, if any, CR
UCS is also predicted by CSA so CSB brings no new information about UCS –
would only provide new information if the UCS changed at same time CSB
was introduced
classical conditionig provides two types of information: what and when of
future events
what:
allows animals to learn that particular event is about to occur
behaviour is determined by memory of event
Hilliard and Domjan – examined conditioning of sexual behaviours in
male Japanese quail
showed that male birds block of grey foam (CS) and then allowed
birds to interact with female bird (UCS) for 5 minutes; after several
such pairings males showed large increase in time they interacted
with CS object
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