THE MODIFICATION OF INSTINCTIVE BEHAVIOR 1

Elicited or Unconditioned Behavior  Occurs without past experience  Modifiable with experience (examples: habituation and sensitization 2

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Some Types of Elicited Behaviour  An eliciting or unconditioned stimulus elicits a response without any prior learning  Types of Elicited Behaviour  Simple Reflex  Orienting Reflex  Taxis (taxes)  Kinesis (kineses)  Fixed/Modal Action Patterns 4

FAPs/MAPs  Sequence of behaviors directed at the eliciting (sign or releasing) stimulussign or releasing  Sometimes requires underlying drive (hydraulic/energy model)hydraulic/energy model  Vigor of response depends on how closely the sign stimulus corresponds to the ideal stimulus (e.g., cute baby)  Small (non-ideal), Normal (ideal), Supernormal (exaggerated ideal)Supernormal 5

Releasing Stimuli 6

Supernormal stimulus An accurate 3-dimensional model of a herring gull's head (a), and a 'supernormal' bill (b). 7

Supernormal stimulus 8

Supernormal stimulus? versus 1950s 1990s 9

10 Lorenz – Tinbergen Model

Energy Model 11  Action-specific energy: an internal force that motivates a specific action  Builds up “internal pressure” that motivates animal to behave in a certain way  IRM (innate releasing mechanism) releases stored energy  Appetitive behavior: instinctive or learned response motivated by action-specific energy and attracted to a sign stimulus

Environmental Release 12  Sign stimuli are environmental stimuli  Some are simple  Others are quite complex  Likelihood of eliciting a FAP depends on  Accumulated level of action-specific energy  Intensity of the sign stimulus  The relationship is inverse  The greater the level of accumulated energy, the weaker the sign stimulus that can release the FAP

Conflicting Motives 13  When two incompatible sign stimuli are encountered, the response may be different from the FAP from either acting alone  A third instinct system, different from either of the two conflicting systems, is activated  Displacement: in a conflict situation, the occurrence of a behavior unrelated to that conflict

Habituation  a simple type of learning which is shown by a change in elicited behaviour over trials  defined as a reduction in responsiveness (frequency, magnitude) over successive trials  sometimes short-lasting and sometimes long lasting 14

Habituation-One Type of Modifiability Eric Kandel and Aplysia 15

Kandel`s Experiments Touch Siphon Gill Withdrawal 16

Habituation touch gill withdrawal 17

Forms of Habituation  Short-Term  lasts only a few minutes  best if stimulus applied at short intervals (2-s)  Long-Term  lasts weeks  best if stimulus applied at longer intervals (30-s) 18

Simplified Circuit 19

Mechanism of Short-term? loss of skin sensitivity fatigue decrease in motor synapse decreases in synaptic transmission 20

Pinsker et al., (1970) Science 167:1740 Evoked Spontaneous Not Muscle Fatigue 21

Mechanism of Short-term? loss of skin sensitivity fatigue decrease in motor synapse decreases in synaptic transmission 22

Not Motor Synapse skin MN SN gill record Kupfermann et al., (1970) Science 167:1743 electrical After Before 23

Mechanism of Short-term? loss of skin sensitivity fatigue decrease in motor synapse decreases in synaptic transmission 24

Skin Sensitivity? skin touch MN SN gill record MN activity to assay habituation Kupfermann et al., (1970) Science 167:1743 Trials 1 to 8 25

Not Skin Sensitivity Kupfermann et al., (1970) Science 167:1743 skin touch MN SN gill record MN activity to assay habituation block 26 Trials

What’s the Mechanism of Short-term? loss of skin sensitivity fatigue decrease in motor synapse decreases in synaptic transmission 27

Mechanism:Short-term Habituation Decrease in neurotransmitter released at the synapse with both the motor neuron and the interneuron! 28

Mechanism of Long-Term Habituation Change in the number of synapses! 29

Properties of Habituated Responses 1.Spontaneous Recovery 2.Dishabituation 3.Generalization 30

Hi Lo Response Number of Presentations Spontaneous Recovery Time Passes Stimulus 31

Hi Lo Response Number of Presentations Dishabituation Novel Event (no time passes) Stimulus Dishabituation 32

Generalization 33

Sensitization- Another Type of Modifiability  enhanced response to a “benign” stimulus after exposure to a “noxious” one (most common)  for example, startle  enhanced response after repeated presentations of a “not so benign” stimulus (less common) 34

Rat Startle 35

Human Startle 36

Thompson/Groves Dual Process Theory 1. S-R System: Habituation 2. State System: Sensitization Competition between two separate processes 37

Conditions Favouring Habituation 1. Calm organism 2. Shorter interstimulus intervals 3. Less variable interstimulus intervals 4. Low intensity 5. Less complexity 6. More trials 7. More Stimulus Specificity 39

Interstimulus Interval 40

Complexity Trials Looking Time 41

42  One example of habituation is when animals gradually eat more of a novel food after initial ingestional neophobia  Ingestional neophobia: the avoidance of novel foods  Habituation of the neophobic response can lead to increased consumption of novel foods

43  Animals can also show an increased neophobic response  If an animal is ill when it ingests a novel food, it may avoid the food in the future  The greater neophobic response when animals are ill is due to sensitization process

44  Experience can also influence the properties of a reward  Homeostasis has traditionally been considered responsible for either increased or decreased effectiveness of a reward  Decreased effectiveness due to satiation  Increased effectiveness due to deprivation

45  However, it appears that habituation and sensitization can also influence  Habituation leads to decreased effectiveness  Sensitization leads to increased effectiveness  Habituation and sensitization can explain changes in reward effectiveness that cannot be explained by homeostasis

46  Habituation is the process that filters out external stimuli of little relevance by raising the sensory threshold to those stimuli  Sensitization decreases sensory thresholds to potentially relevant external events

47  Thus, habituation and sensitization are processes that optimize an animal’s likelihood of detecting significant external events

The Dishabituation Process 48  Dual process theory states that the arousing effect of the sensitizing stimulus causes the habituated response to return  In the absence of the sensitizing stimulus, habituation remains

The Nature of Dishabituation 49  Pavlov suggested that dishabituation is a reversal of habituation  Thus, the dishabituation of the withdrawal response in Aplysia would be a return to the pre-habituation level of neurotransmitter released from the sensory neuron

50  In contrast, Grether proposed that dishabituation results from a process similar to sensitization superimposed on habituation  In Aplysia, this would suggest two processes Decreased neurotransmitter release as a result of habituation Increased neurotransmitter release produced as a result of a sensitization experience

51  Most research supports Grether’s view  Habituation and sensitization are simultaneously independent and interdependent processes  The interdependence of habituation and sensitization has adaptive value  Habituation allows us to ignore unimportant stimuli  Sensitization reinstates the response in case those stimuli now have become important

Opponent-Process Theory 52  Opponent process theory: the theory that an event produces an initial instinctive affective response, which is followed by an opposite affective response

Our Initial Reaction 53  All experiences, both biological and psychological, produce an initial affective reaction  A state: the initial affective reaction to an environmental stimulus in opponent process theory  The strength of the A state is influenced by the intensity of the experience The more intense, the stronger the A state

54  The A state arouses a second affective reaction  B state: the opposite affective response that is elicited by the initial affective reaction in opponent process theory  The B state is opposite the A state

55  Initially, the B state is less intense than the A state  The B state also intensifies more slowly than the A state  After an event has terminated, the B state diminishes more slowly than the A state  The opponent affective response will be experienced only when the event ends

Intensification of the Opponent B State 56  Repeated experience with a certain event often increases the strength of the opponent B state  This reduces the magnitude of the affective reaction experienced during the event  Thus, the strengthening of the opponent B state may well be responsible for the development of tolerance

57  Tolerance: reduced reactivity to an event with repeated experience  When the event ends, an intense opponent affective response is experienced  Withdrawal: an increase in the intensity of the effective opponent B state following the termination of an event

The Addictive Process

59  Opponent process theory offers an explanation for the development of addiction  Addictive behavior is a coping response to an aversive opponent B state  Addictive behavior is an example of behavior motivated to terminate (or prevent) the unpleasant withdrawal state  Parachute jumpers – create a B state in order to feel the A state.