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PSYCHOLOGY 2250 LEARNING. Definition of Learning : In defining learning we could refer simply to overt behavior . For ex., if I see you riding a bicycle I can assume that you’ve learned that skill. Definition of Learning :

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Definition of Learning:

In defining learning we could refer simply to overt behavior.

For ex., if I see you riding a bicycle I can assume that you’ve

learned that skill.

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Definition of Learning:

In defining learning we could also refer to an internal state of


For ex., you all know the 10 provinces (but I can’t tell that just by

looking at you).

So, behavior, or performance, is important.

A good definition of learning should have both components:

Overt behavior and internal state of knowledge

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Learning as knowledge acquisition

Animals learn about stimuli in their environment

Such stimuli serve as signals for some important outcome for ex., a particular odor could indicate that there is food or a predator nearby.

Animals also learn about their own behavior

A certain action will produce a particular outcome

for ex., running to escape from a predator

Usually both types of knowledge occur together. For ex., an animal detects a certain odor that tells it a predator is nearby and this odor evokes an escape response, namely running, to avoid being attacked by the predator.

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Learning: is an inferred change in the organisms’ mental

state which results from experience and which influences

in a relatively permanent fashion the organisms’ potential

for subsequent adaptive behavior.

Why is learning defined this way?

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Key components to definition of Learning

  • Learning is inferred from performance.

  • If there is no behavior to observe then we can’t say for sure

  • whether or not learning has occurred.

  • 2. Learning involves a change in the mental state of an organism

  • We can’t see the neurological structures that underlie this

  • mental state but, in theory, they must exist. Acquired knowledge

  • must somehow be coded or represented in the brain.

  • 3. Learning stems from experience

  • This distinguishes learning from instinct, which refers to

  • behaviors present at birth (i.e., imprinting in certain species of birds)

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Key components to definition of Learning

4. Learning is relatively permanent

Learning persists through time. This part of the definition

guards against mistaking a temporary change in behavior, due to

fatigue for example, for real learning.

5. Learning is a change in the potential to behave.

An animal could acquire knowledge and yet not perform in

such a way as to demonstrate that knowledge. The organism

could have the potential to behave even though the behavior is not


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Other points:

Learning is assessed as a change in behavior —

this could mean an increase or decrease in behavior

For ex., In presence of light — barpress for food

In presence of tone — barpress for shock

What other things could influence behavior or performance

(other than learning)?

  • Fatigue — temporary change so not learning

    • Motivation — maze example; learning occurs but rat not

    • motivated to perform

    • Maturation — could also affect performance but wouldn’t

    • call it learning (i.e., kid reaching cookie jar on top of counter)

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Domjan’s definition of Learning:

Learning is an enduring change in the mechanisms of behavior

involving specific stimuli and/or responses that results from prior

experience with those or similar stimuli and responses (p. 14)

Emphasize distinction between learning and performance




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Habituation and Sensitization

Much of behavior occurs in response to stimuli, that is, it is elicited,

as opposed to spontaneously produced.

The simplest form of elicited behavior is reflexive behavior.

-knee-jerk reflex

-a loud noise causes a startle response

-puff of air at the cornea makes the eye blink

These are all reflexes.

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A reflex involves 2 closely related events:

-eliciting stimulus

-corresponding response

The response and stimulus are linked

-presentation of the stimulus leads to the response and the

response rarely occurs in the absence of the stimulus

(i.e., you don’t go around kicking your leg out unless someone

taps you on the knee).

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  • The specificity of the relation between stimulus and response is a

  • consequence of the organization of the nervous system.

  • Simple reflexes involve three neurons:

  • (1). Sensory— afferent— to spinal cord

  • (2). Motor— efferent— to muscles

    • (3). Interneuron — sensory and motor neurons often

    • don’t communicate directly.

  • This is known as the reflex arc (see Fig. 2.1)

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    Other forms of elicited behavior response is a

    Two of the simplest and most common forms of behavioral change


    (1). Habituation—defined as a progressive decrease

    in the vigor of an elicited response that may occur with repeated

    presentations of the eliciting stimulus.

    (2). Sensitization— defined as an increase in the vigor

    of elicited behavior that may result from repeated presentations

    of the eliciting stimulus.

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    Habituation response is a and Sensitization occur in a wide variety of response

    systems and are therefore fundamental properties of behavior.

    Because elicited behavior involves a very close relationship

    between the eliciting stimulus and the resulting response,

    people often think that the behavior is invariant, or fixed.

    The common assumption is that elicited behavior will occur the

    same way every time the stimulus is presented--not true!

    Behavior is plastic — it changes— it does not occur the

    same way every time.

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    Procedures used to study Habituation and Sensitization response is a

    (examples of repeated stimulation):

    1. Visual attention in human infants

    In babies, visual cues elicit a looking response which can

    be measured by how long an infant keeps her eye on one object

    before shifting her gaze.

    A study by Bashinski, Werner & Rudy (1985)-described

    on p. 37 of Domjan.

    2. Startle response in rats

    A study by Davis (1974)-described on p.38 of Domjan

    The startle response is a defensive response in many


    (i.e., present loud noise, you jump).

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    In rats, we can measure startle in a stabilimeter chamber response is a

    Rat jumps, chamber bounces and sensors detect the amount

    of movement

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    Davis investigated startle in rats by presenting a loud tone.

    2 groups of rats

    -each received 100 tones at 30 sec intervals (110-dB)

    -noise generator that provided background noise

    Group 1Group 2

    soft background noise loud background noise

    (60-dB) (80-dB; not as intense as the tone)

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    Results: tone.

    Repeated presentations of the tone did not always elicit the

    same response

    With soft background noise, repetitions of the tone resulted in

    weaker startle response (i.e., habituation)

    In contrast, when the background noise was louder, repetitions

    of the tone resulted in a bigger startle response (i.e., sensitization)

    With the same tone, see 2 different patterns depending on other


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    These 2 studies show that increases or decreases in responding

    can occur with repeated presentations of stimuli

    Decreases in responsiveness by repeated stimulation = Habituation

    Increases in responsiveness by repeated stimulation = Sensitization

    Lots of everyday example: grandfather clocks, trains

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    Habituation responding is a decline in the response that was initially elicited

    by a stimulus

    However, habituation is not the only effect that can produce

    a decrease in response

    Must distinguish habituation from:

    response fatiguesensory adaptation

    muscles become incapacitated sense organs become

    by fatigue temporarily insensitive

    (i.e.,won’t respond to visual cues if you’re

    temporarily blinded by a bright light)

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    Habituation is stimulus-specific responding

    -if you present a different stimulus, the animal will make

    the response

    -shows that they are not fatigued if they can still make the


    -rules out response fatigue

    Habituation is response-specific

    -an animal may stop responding to a stimulus in one aspect

    of its behavior but continue to respond in other ways

    -e.g., orienting response to mother’s voice may habituate but

    still listen to what she is saying

    -rules out sensory adaptation

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    Dual-Process Theory responding

    Habituation and Sensitization effects are changes in

    behavior or performance

    But what factors are responsible for such changes?

    The Dual-Process Theory (Groves & Thompson, 1970)

    was an attempt to get at this issue

    The DPT assumes that different types of underlying

    neural processes are responsible for increases and decreases in

    response to stimuli.

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    The habituation responding process produces decreases in responding

    The sensitization process produces increases in responding

    These 2 processes are not mutually exclusive— they may be

    activated at the same time.

    The behavioral outcome depends on which process is stronger.

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    Net effect = summation of habituation and sensitization processes

    (not to be confused with habituation and sensitization effects)

    process = underlying neural process/mechanism

    effect = behavior (what you actually observe)

    if you observe habituation, might still have sensitization process

    activated, but its not very strong

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    Groves & Thompson suggested that habituation and sensitization

    processes occur in different parts of the nervous system.

    Habituation processes are assumed to occur in the S-R system

    -the shortest neural path connecting the stimulus

    and the response (sense organs and muscles)

    -similar to the reflex arc

    Each presentation of the stimulus activates the S-R system

    and causes some build up of habituation

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    Sensitization processes are assumed to occur in the sensitization state system

    -this system consists of other parts of the nervous system

    that determine the organism’s general level of responsiveness or

    readiness to respond

    -only arousing events activate state system; not necessarily

    activated with every stimulus presentation.

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    The sensitization state system determines the animal’s readiness to respond,

    whereas the S-R system enables the animal to make the specific

    response that is elicited by the particular stimulus

    Changes in behavior that occur with repeated presentations of a

    stimulus reflect the combined actions of the S-R and state systems

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    Back to Startle Response in rats sensitization :

    When the rats were tested with the quiet background noise,

    there was little to arouse them – the state system was probably

    not activated

    - repeated presentations of the tone activated only the

    S-R system and the result was habituation of the startle response

    When the rats were tested with the loud background noise, the state

    system was activated and the result was an increase in the startle

    response to the same tone.

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    The sensitization State and S-R systems are activated differently by repeated

    presentations of a stimulus

    The S-R system is activated every time a stimulus elicits a response

    -it is the neural circuit that conducts impulses from sensory

    input to response output

    The state system only becomes involved in special circumstances

    -e.g., when stimulus is intense

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    Characteristics of Habituation and Sensitization sensitization

    Time course

    Sensitization is usually temporary

    -sensitization can last for up to a week but not generally a long-term effect.

    -with a stronger stimulus, the effects last longer.

    Habituation can be short-term or long-term, depending on presentation and interval between stimuli.

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    Short-term habituation sensitization :

    -rapid presentations of a stimulus with a short interval between


    -results in habituation quickly but see spontaneous recovery

    -the degree of spontaneous recovery depends on length of

    rest interval.

    Long-term habituation:

    -one stimulus presentation a day

    -see more long-term effects

    -see less spontaneous recovery

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    Tones Every 3 seconds on 1 day sensitization

    Tones Once a Day

    Tones Once a Day


    Blocks of 30 Tones


    Leaton, 1976; see page 46 of Domjan

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    Stimulus specificity sensitization

    Habituation is stimulus-specific

    -if you change the stimulus, see recovery of the response

    Sensitization is not highly stimulus-specific

    -if an animal is aroused, it is usually aroused to a variety of cues

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    Effects of strong extraneous stimuli sensitization

    If you change the nature of the eliciting stimulus you see recovery

    of the habituated response.

    Can also see recovery of the response if the animal is given a rest

    period = spontaneous recovery.

    The response can also be restored by presenting a strong stimulus—

    this is called dishabituation.

    Dishabituation refers to recovery of the response to the

    habituated stimulus following presentation of a different, novel