Learning Chapter 2
What is the course of habituation? ? Effects of time ? Relearning effects ? Effect of stimulus intensity ? Effects of overlearning ? Stimulus generalization
1. Course of Habituation: Habituation occurs whenever a stimulus is repeatedly presented, Decrements in response start large, but get smaller over time 2. Effects of time- After habituation, a respite from the stimulus will lead to recovery of the response. Length of respite is related to the amount of recovery 3. Relearning effects-After a habituation & recovery session a new habituation session leads to faster learning of the habituated response. "Savings in relearning" 4. Effects of stimulus intensity-Stronger initial responses to stronger stimuli are harder to habituate. Weaker initial responses to weaker stimuli habituate rapidly 5. Effects of Overlearning-"below zero habituation" Once habituation shows asymptotic performance learning can still occur. Repeated exposure to the stimulus can prevent recovery, reduce the size of recovery & increase the savings in relearning effect 6. Stimulus generalization: Stimuli similar enough to the habituated stimulus will show the same habituated response. Stimuli different enough from the habituated stimulus will NOT show a habituated response. Note that what counts as similar is discerned from habituation so this is a slightly circular concept!
What about habituation is humans? Where in the neural system does it occur?
Always different areas, but typically see change in activity in sensory areas, not in motor control areas
Why is habituation important & useful? What are some examples?
Any elicited response can habituate in principle Mostly automatic responses to new and sudden stimuli habituate (or can be measured to habituate) in practice Stimulus specific
What about habituation is rats? Where in the neural system does it occur?
Auditory nerve > auditory pathway > brainstem > motor neurons > muscle response
What is an innate behavior?
Behaviors that an animal is able to perform at birth, or which do not require specific external inputs to develop Many learned behaviors are developed out of or are a modification of innate behaviors
What is habituation?
Decrease in the strength of a response after repeated exposure to the stimulus that elicits the response
What is sensitization? Examples What does it tell us about how habituation occurs?
Habituation can be limited or reversed via a process known as sensitization
Examples of Reaction Chains;
Hermit Crab Shell selection, will stop mid through if found perfect shell,
What are reflexes?
Innate movement reliably initiated by applying appropriate stimulus common in newborns: rooting & sucking response, grasping reflex, knee flex, stepping reflex in adulthood: eyeblink, kneejerk, spinal withdrawal Coordinating multiple reflexes or inhibiting reflexes is often a learned behavior
In general terms, how is habituation learned at the neural level in Aplysia?
Learning in the sense of habituation is simple! No new neurons No new synapses No changes in post-synaptic neuron Single change in sensory neuron (absorb less calcium) Leads to observable changes in behavior
What is a tropism?
Movement or change in the entire orientation of an animal (rather than movement of just a body part) subdivided into kinesis and taxis
What are examples of Fixed Action Pattern?
Nut burying by squirrels, the pattern is not learned, young raised in isolation still show the behavior, shown by all squirrels in the species, not extinguished by lack of need
What is subsumption robotics?
Reaction chains have become a paradigm in robotics nested stimulus-> behavior pairings to created a complex behavior The cleaning robot
Kinesis in Woodlice, explained in Control Systems Theory
Reference Input (high humidity)-> Comparator (humidity sensor)-> action system(limbs&muscles)->output(random movement)-> actual input(current humidity)->comparator Disturbances (dry environment)-> comparator->actionsytem etc
Taxis in Maggots, explained in Control Systems theory
Reference input(preferred light level)->Comparator (light sensor)-> Action system(limbs & muscles) -> Output (directed movement) -> Actual input B (Left side light level) <-Disturbance (ambient light level) Actual input A (Left side light level)->Comparator->Action System->output->actual input B
What do we know about universals in human development and biology?
Reflexes, Perceptual systems, development patterns, consistent in brain formation and localization Language- despite surface difference, have much in common emotional univerals- same facial expressions and similar vocalizations, for anger, fear, disgust, surprise, happiness, sadness cultural aspects- tells us tabla rasa is BS
What is an action system?
Rules of the comparator drive the action system. ex. turns the furnace on or off depending on the relationship between reference inputs to the comparator
What are the general properties of habituation?
Salient properties of habituation, especially as observed in humans 1. Course of habituation- response decreases as habituation proceeds 2. Effects of time- habituation is "forgotten" as time passes 3. Relearning effects- appear more quickly at 2nd learning 4. Effects of stimulus intensity- habituation proceeds more quickly with weak stimuli and if stimuli strong enough habituation will never occur 5. Effects of overlearning 6. Stimulus generalization- transfer of the habituation from 1 stimulus to new but similar stimulus
What are supernormal stimuli?
They are replicas or models of real stimuli Sometimes an unrealistic model can elicit a stronger response than the actual sign stimulus itself Ex: oyster catcher bird will choose replica egg over their own egg 1 out of 4 times Ex: female sticklebacks, more attracted to model male sticklebacks
What is kinesis?
Tropism in which direction of movement is initiated by an external stimulus but orientation of movement is random Ex: woodlice, do not seek out humidity just move more (randomly) when it is too dry is a goal directed system
What is a Taxis?
Tropism in which direction of movement is oriented in some relation to the initiating external stimulus Ex: light avoiding behavior in maggot, will move in opposite direction of light, the movements are directed
Nonliving systems in terms of control systems theory?
Watt Steam Engine Piston drives flywheel Flywheel drives load Speed of the flywheel is dependent on many factors Steam pressure Size of the load Lubrication Flywheel needs a constant speed to do work properly The comparator for the feedback system in a Watt steam engine The speed of the weights is directly controlled by the flywheel itself As the flywheel speeds up, the weights push out As the flywheel slows down, the weights push in The comparator for the feedback system in a Watt steam engine The movement of the weights directly controls the steam valve As the weights push in, the valve opens As the weights push out, the valve closes
What are control systems?
a branch of science that deals with goal-directed behaviors in both living creatures and inanimate objects
What is a comparator?
a device that compares its goal state (the reference input) to a current state (the actual input) and signals if the two are not equal
What is a sign stimulus?
a stimulus that initiates a fixed action pattern. They may be general, like any shape size of color of an acorn, or Contagious yawning requires seeing a whole Face, not just the mouth or eyes
What is a reaction Chain?
an innate sequence of behaviors in which the progression from one behavior to the next depends on the presence of the appropriate external stimulus. Portions of the sequence may be skipped or omitted depending on which stimuli are presented and which are not
What is a fixed action pattern?
an innate sequence of behaviors that is elicited by a specific stimulus and, once started, continues to its end whether or not the behaviors are appropriate in the current situation
What is Aplysia (the sea slug or sea snail?) Why is it important here?
in a marine snail Simple neural system (several thousand neurons) Obvious habituated response its a Gill-withdrawl reflex
What role do disturbances play in control systems theory?
influences to the actual input to the comparator that are outside the control of the system itself
What is the gill withdrawal reflex and how does it habituate?
learning occurs in sensory aspects of pathway not in motor aspects no new pathways or neurons, but a reduced output from sensory neurons
What is opponent process theory?
many emotional responses include an initial emotional reaction followed by an after reaction of the opposite emotion A- process is the initial emotional response from an external stimulus B-process is the after emotional reaction to an internal stimulus (process A)
plasticity
nervous systems ability to change as a result of experience or stimulation, sometimes results from the chemical changes in existing synapses rather than from the growth of new synapse
innate human abilities and predisposition
neurons in different parts of the brain are specialized to perform certain functions or to respond to the environment in certain pre-established ways
Examples of Opponent Process Theory
parachutist opiates (tolerance the b-process is the body's mechanism, albeit imperfect, of avoiding, prolonged, in tenses emotions. Extremes of emotion, whether positive or negative, tax the body's resources, so when any a-process persists for some time, the corresponding b-process is evoked to counteract it, at least in part.
What is feedback in a closed loop system?
the outputs of the action system changes the input to the comparator, the system keeps itself in check
why does the manifest affective response look like it does?
the pattern of an emotional response changes with repeated presentations of the same stimulus the theory states that the primary emotional response exhibits a sort of habituation, it becomes smaller, while at the same time there is a marked increase in the size and duration of the after-reaction. with repeated stimulation the b-process rises more quickly and reaches a higher maximum and is slower to decrease after the stimulus is terminated
What is an output system?
the product of the action system changes the environment in which the system in located
vision and opponent process theory
the visual system has receptors that react in opposite ways to three pairs of colors. Opponent process theory explains why most people perceive four primary colors: red, green, blue, and yellow. Opponent process theory also accounts for complementary or negative afterimages.
How can we describe these as separate behaviors?
think not of as a single behavior, but a series of separate behaviors, each triggered by a separate stimulus; Each can then be thought to continue to its end once the appropriate stimulus is available
