Chapter 2: Elicited behavior, Habituation, and sensitization • Elicited Behavior • behavior is a reaction to a stimulus in the environment. • Food salivation • Bright light pupil dilation.
The simplest form of elicited behavior is the reflex. • Components of a Reflex Arc • All reflex arcs have five essential components • 1. receptor • reacts to a stimulus. • 2. The sensory (afferent) neuron • conducts message to CNS • 3. The integration center • consists of one or more synapses in the CNS. • 4. The motor (efferent) neuron • conducts from CNS to an effector. • 5. The effector, • muscle fibers or glands, • contracts or secretes.
The reflex arc just described = simplest situation. • Often other neural connections are involved. • Notice that the Reflex arc does not require any willful conscious act • Thus - elicited
Reflexes appear to have evolved to protect the well being of the organism. • withdrawal from pain • eyeblink • pupillary reflex • Sneeze, cough, vomit • patellar reflex • rooting reflex. • salivation • release of digestive fluids. • Animals with reflexive tendencies had an advantage
Ethology and Modal Action Patterns • Ethologists study the role of behavior within the context of species-specific behaviors. • This is in contrast to the general processes approach used by most psychologists • Ethologists • behavior is generally instinctive. • often study animals in the wild rather than the laboratory
Consummatory behaviors • behaviors that are crucial for survival. • feeding, courting, reproducing, and care for offspring. • innate, genetically determined survival behaviors. • For Example • Imprinting. • Konrad Lorenz • Why do geese imprint, but other birds/animals (robins) do not? • PrecocialvsAltricial?
Ethologists try to find the variables that are responsible for eliciting the behavior. • imprinting = two important factors. • 1. The object must be moving • doesn’t matter if it is living or not • ultra lights • 2. The imprinting must occur within a critical period • (13-16 hours after hatching). • Critical Period for learning some things for humans? • language
Modal Action Patterns. (MAP’s) • modern Ethology abandoned the term instinct • MAPs vs Reflexes • MAPs are • more complex • consist of a long series of reflex-like acts • more variable, though still stereotypic • less likely to be evident at or soon after birth.
In addition, to qualify as a MAP, a behavioral sequence must meet four specific criteria according to Moltz (1963) • 1. Stereotyped • occurs the same way each time • 2. continue to completion once begun • difficult to disrupt • 3. latent period • once completed, some time must pass before behavior appears again • 4. innate • the animal must perform the full integrated behavioral sequence the first time its elicited
Like Reflexes MAPs are highly adaptive • Protection from predators • Cat – arch back, fluff hair, hiss • Protection against the elements • Migration • hibernation • getting food • Pigs rooting • spider webs • courtship and mating • Big Horn Sheep • Ducks • care for young • Birds • Nests • Gathering food • Wasps that capture spiders
Modal Action Patterns are released by a sign stimulus • Sign stimulus • a specific environmental event that triggers an MAP • Female pheromones often trigger mating behavior in males • The sign stimulus works like a key to unlock an innate releasing mechanism • innate releasing mechanism • a neural mechanism that is stimulated by a sign stimulus. • controls the modal action pattern
Examples • Geese with Eggs • Rolling away? • What if it slips on way back? • stereotyped • Larger eggs? • Supernormal stimuli • Birds feeding young • Cowbirds • Herring gull studies • Which beak works best?
Do humans exhibit Modal Action Patterns? • sleep? • Stereotyped? • continue to completion once begun? • latent period? • Innate? • emotions? • sex?
Effects of Repeated Stimulation • Descartes thought that a reflexive response would occur the same way each time it was elicited • However – elicited behavior are not invariant • Habituation. • repeated exposure to a stimulus reduces responding to that stimulus.
Habituation is a very simple form of learning • Very useful tool for understanding animal and infant behavior. • Can you distinguish between “ba” and “pa” • Infants? • Used suck rate as response • Pacifier with an embedded switch
As simple as habituation is, it can be used to tell us a lot about a nonverbal organism • Other race effect • Caucasian infants (3.5 months old) • Group 1 (Caucasian faces) • shown a Caucasian face until habituated • Group2 (Asian faces) • Shown an Asian face until habituated • Test • Both groups shown novel faces • New Caucasian face for group 1 • New Asian face for group 2
HOWEVER, • Repetitive stimulation does not always cause habituation. • sometimes you get sensitization. • My father and motorcycle • emotional response • flee • do not habituate • likely to be more responsive to other stimuli. • tap on the shoulder • drop a wrench. • My dog and car AC
Davis (1974) • sensitization and habituation to the same stimulus. • 110 db noise = loud. • Gp1 = rats housed in a quiet chamber = 60 db • Gp 2 = rats housed in a loud chamber = 80 db • One of the groups decreased their startle response to the 110 db noise after repeated presentations. • The other group increased their startle response to the 110 db noise after repeated presentations. • Which group is which? • What phenomenon does each group demonstrate?
What determines whether we get habituation or sensitization? • Dual process theory • Two simultaneous processes • S-R system • Reflex arc • State system • Involves additional parts of the nervous system that regulate levels of arousal
The S-R system and State system are additive – but in opposite directions • The more active system will determine whether habituation or sensitization is displayed • Example • Checkerboard study in book. • Infants shown checkerboards • 4 x 4 • 12 x 12
Habituation versus Sensory Adaptation and Response Fatigue • Sensory Adaptation • Bright light – blinded • Loud noise – can’t hear • Response Fatigue • Too tired to move
Stimulus specificity • Habituation is stimulus specific • Stop responding to one thing, but if there is a change in the stimulus the habituation goes away. • Dishabituation • Sensitization is not stimulus specific • If working in a loud factory you may be more reactive to other stimuli • Tap on the shoulder • This is consistent with dual process theory • S-R system = specific to sensory input • State system = general arousal
Time course for habituation • Short-term = seconds to minutes • Long-term = may persist for many days • Leaton (1976) • Startle response in rats to loud high pitched tone