Chapter 3 Habituation, Sensitization, and Familiarization: Learning About Repeated Events

Modified: 2024-09-09 8:28 PM CDST

Learning comes in all kinds of ways. But, even the simplest types are not easily understood. This chapter looks at non-associative learning. In other words, learning that takes places with single stimuli. Specifically, we will look at habituation and sensitization. Although the manifestation of both are relatively simple their underlying explanations are not.

Jeffery Dahmer Example

• Your text emphasizes the circumstances surrounding the Jeffery Dahmer case.
  • His grandmother could not habituate to the noises he made at her house (sensitization).
  • Many apartments in his neighborhood stunk (habituation).
  • People ignored news stories about people who disappeared.
  • Dahmer learned how to best pick his victims (perceptual learning)

Definitions

• Habituation: A decrease in the strength of occurrence of a behavior after repeated exposure to the stimulus that produces that behavior.
  • Habituation is one of the simplest forms of learning and consists of NOT making a response to repetitively presented stimulus.
    • Examples include the motor responses such as
      • a dog not flicking its ear while sleeping while someone lightly strokes the dog's ear
      • people who live near the railroad not responding to the sounds of nightly regularly passing trains,
      • buying a new, loud wall clock and eventually habituating to the noise it makes.

    • Stimuli which lead to habituation are typically low in intensity and repetitive.
      • But, habituation can occur to stimuli without those characteristics as well.
      • For instance, a hunting dog can become habituated to the loud and irregularly spaced sound of his hunter's gun.
      • Habituation is a form of non-associative learning, meaning that only one stimulus is being presented.
        • Video: Explaining Habituation
  • Effects of habituation
    • Examples:
      • Loud repetitive noises
        • the 3:11 am freight train that runs by your house in the country
        • the cows mooing across the street in the country
          • (true story: we had guests once, asked how they slept, they said the cows kept them awake. We said, "What cows.")
            • they were sensitized, we were habituated
      • Emotions
        • Crime
          • Magnolian moved to Houston and was shopping
          • She came out, got in her car, realized her wheels and tires were gone (car was on cinder blocks)
          • She called police, they made report, said it happens all the time in Houston
          • Police said she would not get her wheels and tires back
        • School shootings
          • 2024 is now the year with the highest number of school shootings
          • Unfortunately, we're habituating to it
        • Beggars
          • Do you notice them?
    • Habituation is less likely when:
      • Stimulus changes
      • Too much time passes between stimulus occurrences
      • The less frequently the stimuls occurs
      • Stimulus is too intense (but organisms can habituate to strong stimuli)
• Sensitization: A phenomenon in which a salient stimulus (such as painful electric shock) temporarily increases the strength of responses to other stimuli.ma
  • Sensitization causes the organism to make a stronger and stronger response.
  • Sensitization can occur to stimuli other than the original stimulus.
  • Examples include motor responses such as:
    • Your roommate's loud stereo. It disallows you efforts to study. Eventually, it prevents them.
    • Torture: Torturers might apply the same level of painful shock repeatedly on different parts of the victims body.
      • The same level of shock becomes psychologically more painful
    • Celebrities reacting strongly to the constant exposure to the public and to paparazzi and they finally have a sensitizing response.
  • Stimuli which lead to sensitization are typically strong and not regular in occurrence.
    • Video: Explaining Sensitization
• Desensitization: n. a reduction in emotional or physical reactivity to stimuli that is achieved by such means as deconditioning techniques. See also covert desensitization; in vivo desensitization; systematic desensitization. (APA)
• Dishabituation: A renewal of a response, previously habituated, that occurs when the organism is presented with a novel stimulus.
• Acoustic Startle Reflex: BANG!
  • Did you jump?
  • In class, I'd make a loud noise to demonstrate this reflex.
  • Then I'd go: BANG!BANG!BANG!BANG!
  • Guess what? No more acoustic startle reflex. Organisms habituate.
• Orienting Response: Discovered by Pavlov. An organism's response to a novel stimulus. Organism notices, pays attention. Extinguishes quickly (aka, it habituates)
• Spontaneous Recovery: Reappearance (or increase in strength) of a previously habituated response after a short period of no stimulus presentation.
  • One extinction episode is usually not enough to undo completely a conditioned response.
    • So, when an animal is returned to the original conditioning situation and allowed to make the conditioned response, it will.
      • In order to obtain complete extinction, many extinction trials will be required.
      • Think of how many trials were required for the original conditioning.
      • It only makes sense that a similar number of trials will be required for complete extinction.

    • Think about someone trying to quit drinking alcohol.
      • When they return to the same situations where they used to drink, they must battle spontaneous recovery.
      • That is why programs like Alcoholics Anonymous try to prevent their members from returning to their old haunts.
    • Another good example is when a recently divorced couple visit each other.
      • They may, through spontaneous recovery, engage in an old conditioned response (e.g., lovemaking, AKA 'sex with ex'), much to the chagrin of their new partners.
• EDA or Galvanic Skin Response: Fluctuations in the electrical properties of a person's skin that are the consequence of activity in the peripheral nervous system.
• Novel Object Recognition Task: When organisms detection of and response to unfamiliar objects are used to measure its memories of past experiences with those objects.
  • Video: Explains Novel Object Recognition Task.
• Priming: When prior exposure to a stimulus can improve the ability to recognize the same stimulus later.
  • Video: Tony Robbins explains priming.
  • Priming tends not to last long.
• Perceptual Learning (aka Statistical Learning): When experience with a set of stimuli makes it easier to distinguish those stimuli.
  • Here, the learning takes place through mere exposure, thus it is non-associative.
  • Perceptual learning tends to last longer than priming.
• Spatial Learning: the acquisition of knowledge about one's surroundings.
  • Example: Unlearned and Learned
    • The digger wasp (you will need to scroll down) demonstrates a situation in which there are both unlearned and learned components.
• These digger wasps live near the coast in the Netherlands.
• They hunt for caterpillars, stun them, lay eggs in them, and bury them in small burrows.
• All of those behaviors mentioned above are unlearned, meaning that all normal digger wasps will engage in such behavior without having to learn it.
• By the way, the caterpillars are put into a state or torpor or immobility by the sting. The young wasps hatch and then eat their way out of the live but immobile caterpillar.
• The learned part of this example comes in navigating from the area in which the caterpillars are found to the various burrows each wasp maintains.
• Each burrow is visited several times before it is finally sealed, and each wasp maintains several burrows.
• The Baerends, Tinbergen's colleagues, were able to demonstrate that the wasps were navigating by learned cues.
  • They did so by moving the landmarks near burrows.
  • When the wasps returned, they landed where the burrow should have been.
  • Eventually, however, they learned the new location.
  • This example gives us an idea about a function of learning, namely, to help animals deal with environments that change.
  • The beach will change daily, but caterpillars have been the same for millions of years.
  • More recent research showed that plants being attacked by caterpillars emitted plant hormones that the wasps could detect, thus making their search easier.
• Example: Latent Learning. (from Kardas history text)
  • Tolman and Honzik (1930) decided to investigate whether learning required a reinforcer (food, in this case). They trained three groups of rats in the same complex maze using the average number of errors per trial as the criterion for learning. Those errors should drop over time, exhibiting a classic learning curve. One group, the control (HNR), was never fed. Another group was always fed (HR), and the final group (HNR-R) was only fed after the 11th day of training. If learning required a food reinforcer, then that last group should begin learning the maze only after commencing to eat on the 11th day (see Figure 11.3). (Notice that your text does not show the HNR group.)
  • That is not what happened. Instead, once the last group began to be fed, their errors dropped precipitously. Tolman and Honzik interpreted these data by saying that those rats had already learned the maze, but that it took the presence of food in the goal box for them to perform or demonstrate their learning. They called the phenomenon latent learning because the learning, they argued, had already taken place. They argued that the new presence of the food reinforcer now changed the situation, causing their errors to go down accordingly. In their theorizing, reinforcement was not necessary for learning.

• Latent Learning and Cognitive Maps (also from my history text)
  • Jensen (2006) noted that nearly all of the general psychology textbooks he surveyed gave incomplete and misleading accounts of the current status of latent learning and cognitive maps. The history of latent learning shows that “There was no resolution at all . . . The debate ended because it became clear to psychological researchers and theorists that given the hypothetical nature of the variables involved in latent learning, no empirical solution was likely” (p. 195). He argued that most current textbooks do not tell students that the issue of latent learning was essentially abandoned. Instead, those texts uncritically point to Tolman’s cognitive map as the only solution left standing. Later he notes that “although the cognitive map metaphor might retain its appeal, a close examination of the metaphor as a scientific explanation for human and animal navigation through spatial environments exposes substantial weaknesses” (p. 204). He argued that other historical and contemporary explanations for latent learning do exist; they are just no longer covered in introductory psychology texts. Ultimately, Jensen was concerned with the pervasive effect of such historical misinformation upon new psychology students, especially those who eventually major in the discipline. (I found it interesting that your text mentioned latent learning so often.)
• Cortical plasticity: the capacity to to change cortical organization as a result of experience.
  • Example: musicians's primary motor cortex may change as a result of practice if they begin playing an instrument as children.
• Constraint-induced movement therapy: a motor rehabilitation technique in which unaffected limbs are restrained to increase usage of dysfunctional limbs.
  • Example: Taub deafferented monkey's arms and forced them to use those arms. The arm's motor function was not affected but their sensory function was.
    • Later, Taub became the focus of animal activists.
      • Video: Shows child forced to use affected arm as therapy.
• Sensory Prosthesis: device to supplement or substitute for faulty sensory modality, such as vision or hearing. These devices interface with brain areas that normally process those sensory inputs.
  • Video: Shows differences between older, mechanical prostheses and newer, directly connected to the nervous system types.
• Cochlear Implant: sensory prosthesis that directly stimulates the auditory nerve to produce new and different hearing sensations in affected individuals.
  • Cochlear implants:
    • roughly simulate neural activity
    • work best in young children and adults who recently lost hearing
    • speech sounds produced are different and must be relearned
    • in cats, significant changes in their auditory cortex occur
  • Why don't we know this about humans?
    • Must see brain directly before and after (ethics)
      • Cats:
        • Two groups:
        • Control: no cochlear implant, sacrifice cat, look at brain
        • Experimental: cochlear implant, sacrifice cat, look at brain
      • Get it? See the ethical issue?

Learned vs. Unlearned

• Let's take a wider look at learning in general.
  • The study of learning has been one of the central foci of psychology since the turn of the twentieth century.
    • During the heyday of behaviorism, learning was psychology in America.
    • Although that emphasis has subsided somewhat today, a complete understanding of modern psychology requires us to know the research on learning.
    • Learned behaviors can be distinguished from unlearned behaviors only if we observe the development of those behaviors.
    • They cannot be differentiated on a simple to complex dimension.
  • Unlearned behaviors are "built-in" in some sense.
    • Either they unfold via the process of maturation, or they manifest themselves at some stage in life in all or nearly all members of the same species.
    • In other words, unlearned behaviors are more consistent in form and timing of development than learned behaviors.
    • Learned behaviors must be acquired.
    • Learned behaviors will exhibit a wider variability than unlearned, and will not be as universally distributed as unlearned behaviors.
    • Some examples of each (below) will help to clarify these distinctions.
  • Example: Unlearned
    • The three-spined stickleback is a small, freshwater, European fish. It lives in small streams.
      • Males of this species build nests during the mating season and then defend the cylinder of water above the nest from other males.
      • Males develop red bellies during mating season, and that is the primary cue that other males use to distinguish males from females.
      • In fact, Tinbergen showed that even crude fish models with red bellies were attacked by resident males, but accurate models without red bellies were not.
      • Females do not develop red bellies.
      • When a female enters a male's territory, he engages in the "zig-zag" dance.
        • If a female is receptive, she will follow the male to his nest, lay her eggs inside, and leave.
        • The male will then fertilize the eggs, fan water through the nest with his tail to prevent rotting, and continue to defend the nest.
        • The point of this long-winded example is that ALL normal male sticklebacks will engage in this kind of behavior WITHOUT having to learn it.
        • (Papa stickleback does not have to explain to Junior stickleback about the birds and the bees.....) The above is an example of a complex unlearned situation.
• Example: Learned (nearly entirely)
  • The final example involves human and monkey parenting. An interesting question is, "How much of human parenting is learned?"
    • Unfortunately, we cannot run the experiment to answer that question for ethical reasons. (e.g.,. Take a number of children, raise them without parents....)
    • Harlow, however, was able to run just such an experiment with rhesus monkeys.
      • Harlow separated some mothers and their offspring shortly after birth.
      • Some monkey infants were reared in total isolation, others with "surrogate mothers," others with other monkey infants, and still others were not separated from their mothers.
      • The infants raised in total isolation were completely abnormal.
      • The infants reared with surrogate mothers fared somewhat better, and they developed an attachment to the soft, warm surrogate mother.
        • Later in life, the males reared in this condition could not become fathers because they were unable to copulate with females.
        • Females in this group did copulate successfully, but made horrible mothers.
      • Both males and females in the group that was reared with other monkeys could copulate and made adequate, if somewhat below average, parents.
      • In rhesus monkeys, then, parenting skills are learned.
    • Parenting skills are learned in humans as well.
      • Many of us have had experience with infants prior to giving birth to our own.
        • However, the experiences surrounding the birth and raising of the first child are the major time of learning for most parents.
        • Subsequent children are treated very differently because of those experiences. (Parents learned from having their first child.)
          • True story: We kept visitors away for a few weeks after our first child was born. By the time our third was born seven years later we took her to restaurants before she was a week old.
      • Interestingly, our society requires no demonstration of capacity to parent. But, society requires demonstration of capacity to drive an automobile.
        • Lykken and others have argued that some formal training in parenting should be required.
          • Informal avenues for training exist, such as LaMaze training and intervention programs for some parents.
        • The research on child abuse is instructive here.
          • Child abusers are much more likely to have been abused children themselves, giving rise to a cyclical hypothesis of child abuse.
          • Intervention programs aim to break that cycle.
    • So, understanding learning provides insight into much of human behavior because so much of human behavior is learned.

Definitions of Learning

• The classic definition of learning is that learning is a CHANGE in behavior as a result of experience or practice.
• A newer definition, one with a cognitive orientation is that learning is the acquisition of knowledge.
• The two definitions are similar, but not equivalent, because knowledge acquisition does not always lead to behavioral change.

• Notice how your text attempts to link learning, memory, physiology, and clinical issues.
  • Take the following hypothetical example.
    • Everyday I lecture, I walk in to class and I turn off the lights in the room so that I can project my lectures.
    • One day, however, the light switch shocks me. I forget to tell the physical plant to fix it.
    • The next time I lecture, I reach for the switch but stop. Why?
  • Using the first definition, I would say that the previous day's experience led to a change in my behavior.
  • Using the second definition, I would say that I acquired the knowledge that there was something wrong with the switch, and that I had not yet reported it. So, that knowledge prevents me from touching the switch.
  • Notice that we can easily use the first definition with both animals and humans because all of the variables are external.
  • However, because we cannot get inside other animals' heads, we can only use the second definition on humans.
  • Notice that I am not saying that animals do not have thoughts.
• Rather, I am saying that we can only be aware of our own thoughts, and informed of the thoughts that other humans communicate to us. Animals cannot communicate their thoughts to us.

Different Primary Processes of Learning and Memory and their Descriptions (Krause & Sanz) (You will want to refer back to this table throughout the semester.)

• Learning/Memory Process	Description	Example
  Habituation/Sensitization	Increased or decreased response to repeated stimulation.	Reduced or enhanced gill withdrawal reflex in sea slugs following repeated stimulation.
  Associative learning	A change in responding due to the co-occurrence of one more stimuli	Acquisition of appetitive response toward cues previously paired with sweet (sucrose) solution in rats.
  Operant conditioning	A change in behavior due to rewarding or punishing consequences	Pigeon pecking a key in order to obtain grain, or avoidance of location in which a predator had been previously encountered.
  Social/Observational learning	Acquisition of specific behavioral pattern or making a choice following the opportunity to perceive another engaging in the behavior.	Seeking out specific food sources that were present on the breath of conspecifics.
  Declarative memory	Memory for individual, personal events and their spatial and temporal arrangement. Includes memory for factual (semantic) information	Remembering the location, type of food source, and time in which caching took place in scrub jays (episodic).
  Spatial memory	Memory for physical environment and one’s orientation within that environment	Learning and remembering the pathway required to return to a burrow or nest.
  Working memory	A set of cognitive processes that are involved in the temporary holding and manipulation of information	Rats keep track of whether a reward was available in each of eight arms in a radial maze.

Extinction

• In lay terms, you can think of extinction as the "unconditioning" or unlearning of a conditioned response.
  • That sentence tells us something very important.
    • That is, extinction is not like forgetting.
    • We do not simply forget responses that have been conditioned.
    • Rather, if we want to remove conditioned responses, we have to extinguish them.
    • That fact has important implications in areas like therapy and child rearing.

  • Many years ago, Skinner conditioned some pigeons to make an operant response.
    • He then put those pigeons on a vacation; he let them just spend their time in the lab without doing any more operant conditioning.
    • When he returned them to the conditioning situation, some years after their original conditioning, they all exhibited the conditioned response.
    • So, in a sense, conditioning is forever, unless it is extinguished.
  • How do we extinguish?
    • In classical conditioning, we remove the UCS.
    • In operant conditioning, we remove the reinforcer.
    • Over a period, the animal will learn that the CS, or the operant response, is no longer being reinforced.
      • (The UCS is also considered to be a reinforcer. later in this chapter.)
• We will see soon, however, that conditioned behaviors can make a reappearance, even after extinction.

Spontaneous Recovery

• One extinction episode is usually not enough to undo completely a conditioned response.
  • So, when an animal is returned to the original conditioning situation and allowed to make the conditioned response, it will.
    • In order to obtain complete extinction, many extinction trials will be required.
    • Think of how many trials were required for the original conditioning.
    • It only makes sense that a similar number of trials will be required for complete extinction.

  • Think about someone trying to quit drinking alcohol.
    • When they return to the same situations where they used to drink, they must battle spontaneous recovery.
    • That is why programs like Alcoholics Anonymous try to prevent their members from returning to their old haunts.
  • Another good example is when a recently divorced couple visit each other.
    • They may, through spontaneous recovery, engage in an old conditioned response (e.g., lovemaking, AKA 'sex with ex'), much to the chagrin of their new partners.

Non-Associative Learning Theory

• Dual Process Theory
  • The reference below is the one from pp. 84-86 in your text.
    • Habituation and Sensitization are independent of each other but act in parallel.
      • Groves, P. M., & Thompson, R. F. (1970). Habituation: A dual-process theory. Psychological Review, 77(5), 419–450. https://doi.org/10.1037/h0029810

• Abstract

  • Presented a dual-process theory of response plasticity to repeated stimulation. 2 hypothetical processes, 1 decremental (habituation) and 1 incremental (sensitization), are assumed to develop independently in the CNS and interact to yield the final behavioral outcome. Behavioral experiments are presented, using both the hindlimb flexion reflex of acute spinal cat and the acoustic startle response of intact rat, which are consistent with this theory. Neurophysiological experiments indicate that the 2 processes have separate and distinct neuronal substrates. The dual-process theory and other current theories of response habituation are evaluated in terms of these and other recent findings. (6 p. ref.) (PsycInfo Database Record (c) 2023 APA, all rights reserved
• Video explaining dual process theory

Brain Substrates

• The magic bullet in learning and memory would be to link behavior (learning), thinking (memory), to physiology. But as chapter 2 indicated doing so in humans is an enormously complex (impossible?) task.
• Thus, researchers have attempted to work with organisms that possess many fewer neurons in their nervous systems.
  • The horseshoe crab, for instance, possesses relatively enormous neurons. It was a suitable organism for the initial studies on neurons.
  • Similarly, the sea slug (Aplysia) has played the same role in non-associative learning thanks to the Nobel Prize winning research of Eric Kandel.
• Eric Kandel won the Nobel Prize for Physiology and Medicine in 2000 (shared with Arvid Carlsson and Paul Greengard) for his research on the sea slug, Aplysia californica, (Castellucci & Kandel, 1976). Kandel and his coworkers showed that simple learned responses (habituation, sensitization, and dishabituation) were controlled by specific sensory and motor neurons. In other words, they were able to link behaviors to biological processes. That research led to insights about learning in animals with relative few brain cells (20,000 in Aplysia and 300,000 in Drosophila, the fruit fly), that the hippocampus contains a cognitive map, how short-term memories convert to long-term, that increases in synaptic strength lead to memory formation, while synaptic depression provides a parallel mechanism for memory storage (Kandel, 2009).
• Eric Kandel Noble Prize Page Biography
  • "After an extensive search that included crayfish, lobster, flies, and the nematode worm Ascaris, I settled on Aplysia, the giant marine snail. Aplysia offered three major technical advantages: (1) its nervous system has a small number of cells, (2) the cells are unusually large, and, as I realized with time, (3) many of the cells are invariant and identifiable as unique individuals." 
  • "We identified specific sensory neurons and motor cells that produced movements of the gill. Next, we found that the sensory neurons made direct connections to the motor neurons as well as indirect connections through interneurons, both excitatory and inhibitory. The aversive tail stimuli that produced sensitization of the gill-withdrawal reflex activated modulatory interneurons that acted on terminals of the sensory neurons. We now could turn to think about how learning might occur in this reflex."
    • Video: Research on sea slugs

Clinical Perspectives

• Rehabilitation After Stroke: Habituation Going Awry
  • Humans who lose sensory function in a limb following stroke often quit using that limb even though the motor circuits work.
    • Constraint-induced movement therapy can remedy this condition
      • Video: Shows child forced to use affected arm as therapy.
• Sensitization to Stress in Anxiety and Depression
  • Rat receiving low doses of amphetamines were sensitized to display similar effects (stereotyped behavior) to rats given higher doses.
    • Similarly, human depressed patients show stronger responses to stressors than do non-depressed people.
    • Also, sensitization might contribute to the development of anxiety disorders, especially obsessive-compulsive disorder (OCD).
      • OCD: a personality disorder characterized by a pervasive pattern of excessive perfectionism, orderliness, mental and interpersonal control, inability to compromise, and an exaggerated sense of moral responsibility, included in DSM-IV-TR, DSM-5, and DSM-5-TR. Also called compulsive personality disorder. (APA)
• Does that mean humans should avoid stressful events?
  • Animal research suggests not.
    • Exposure to minimal stresses over time may lead to greater resilience.
      • Resilience, refers to how individuals differ in their responses to the same situation or stimulus. One example is mental toughness. Crust (2008) reviewed previous research on that phenomenon and concluded that more research is needed in order to better define it. Specifically, he recommended that mental toughness be examined by a variety of methodological approaches, and that populations other than elite athletes be included more often. Couzin-Frankel (2018, p. 971) following events such as hurricane Katrina wrote, “One psychologist coined the term ordinary magic to describe the mix of features that brews resilience. From our stories, we learned that no clear-cut recipe exists.”
• Human-Machine Interfaces: Regaining Sensory Modalities Through Perceptual Learning
  • Sensory Prosthesis: device to supplement or substitute for faulty sensory modality, such as vision or hearing. These devices interface with brain areas that normally process those sensory inputs.
    • Video: Shows differences between older, mechanical prostheses and newer, directly connected to the nervous system types.
  • Cochlear Implant: sensory prosthesis that directly stimulates the auditory nerve to produce new and different hearing sensations in affected individuals.
    • Cochlear implants:
      • roughly simulate neural activity
      • work best in young children and adults who recently lost hearing
      • speech sounds produced are different and must be relearned
      • in cats, significant changes in their auditory cortex occur
    • Why don't we know this about humans?
      • Must see brain directly before and after (ethics)
        • Cats:
          • Two groups:
          • Control: no cochlear implant, sacrifice cat, look at brain
          • Experimental: cochlear implant, sacrifice cat, look at brain
        • Get it? See the ethical issue?

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