Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_27_библиотеки_им_акад_М_И_Перельмана
.pdf
As a variation, attend the same class resolved to keep both feet on the floor
throughout the entire lecture. You might ask a classmate to keep an eye on you to
see if you cross your legs.
How did you do? Did you find yourself yearning to look at the clock or cross your
legs? What does this tell you about “ironic processes” in mental control?
Ironic processes have been observed in a wide range of behaviors. In an
intriguing study of this effect on the control of motor behavior, Wegner, Ansfield, and
Pilloff (1998) had subjects hold a pendulum (a crystalline pendant suspended from a
nylon fishing line) over the center of two intersecting axes on a glass grid, which
formed a “+”. Some subjects were instructed simply to keep the pendulum steady,
while others were more specifically told not to allow it to swing back and forth along
the horizontal axis. Try this yourself and you’ll find that it’s not easy to prevent at least
some movement. In this experiment, however, the pendulum swung horizontally more
when this direction was specifically forbidden. To further examine the role of mental
distraction, some subjects were also required to count backward from a thousand by
sevens while controlling the pendulum. In this situation, the ironic effect was even
greater. Among subjects who specifically tried to prevent horizontal movement but
could not concentrate fully on the task, the pendulum swayed freely back and forth—
in the forbidden direction. Using a similar method, these researchers found that
people were most likely to overshoot a golf putt when they specifically tried not to
overshoot but were distracted while putting. It may seem both comic and tragic, but at
times our efforts at self-control backfire, thwarting even our best intentions. For
psychologists, and everyone else for that matter, the key is to learn how to minimize
these ironic effects.
Illustrating Wegner’s proposition that “any attempt at mental control contains the
seeds of its own undoing,” research shows that people are most likely to overshoot a
golf putt when they are specifically trying not to overshoot but are distracted while
putting.
iStock.com/PhotoTalk
Thinking Like a Psychologist About Consciousness
“A penny for your thoughts?” Over the years, psychologists have equated
consciousness with attention and have examined varying states of awareness,
ranging from sleep and dreams to hypnosis and the effects of mind-altering drugs.
We have found in this chapter that people can sometimes control the contents of
consciousness. Research on selective attention shows that as we focus the spotlight
of awareness on one stimulus, we can screen out irrelevant competing information.
At times, we can divide our attention, simultaneously engage in two or more activities,
and process information without awareness. Yet there are also times when we cannot
control what we think about—and trying to do so can backfire.
For researchers, it is crucial to consider what is underlying consciousness. In
other words, it is critical to keep in mind that neural networks are the construction of
our mind. Understanding consciousness, then, is a multidisciplinary endeavor. It
requires an understanding of not just our neurology but also what we attend to
(sensation and perception), our experiences (learning and memory), our development
(lifespan development), our health, and so much more. Consciousness represents
just the tip of the iceberg. It represents what we know we are attending to and what
https://t.me/medicina_free
we can recall. As we will explore in Chapter 6 regarding memory, so much of our
experiences occur beyond our awareness. Understanding consciousness, then, is a
valuable endeavor for psychologists, not only because of its implications for so many
other fields of science but also because it provides a gateway into our own
awareness of ourselves, the world around us, and our very being.
SUMMARY
Attentional Processes
Psychologists generally define consciousness in terms of attention—an
awareness of the sensations, thoughts, and feelings that one is attending to at a
given moment.
Selective Attention
Studies of the cocktail party phenomenon demonstrate that people can use
selective attention to focus on one stimulus and virtually exclude other stimuli from
consciousness. Many of these studies use a dichotic listening task in which subjects
hear competing messages over headphones and must follow what is said in one ear
while ignoring the other.
Divided Attention
Other listening experiments show that divided attention is possible: Some stimuli
penetrate consciousness even when we are focused on something else. Moreover, if
we are so experienced at a particular process that it becomes automatic, we can do
other things at the same time. The Stroop test demonstrates that experienced
readers process word meanings automatically, without effort or awareness.
Influence Without Awareness
Research shows that people can be influenced by subliminal messages—
information that is presented “below” our threshold of awareness. Mere exposure to a
stimulus increases liking, even when the exposure is subliminal. This is shown in
studies on priming, where subliminally presented concepts appear to facilitate, or
“prime,” responses in a subsequent situation.
Sleep and Dreams
Until recently, there were many myths about sleep and dreams, but little was
actually known about these processes.
The Sleep-Wake Cycle
As biological organisms, humans experience regular fluctuations known as
biological rhythms. Our daylong circadian rhythm, such as the sleep-wake cycle,
is controlled by the suprachiasmatic nucleus of the hypothalamus, which detects light
via the retina. Cut off from sunlight, humans tend to drift toward longer daily cycles.
When our rhythms are disrupted, we may experience reactions such as jet lag.
Night Work, Sleeping, and Health
Both biological and social clocks set the body for activity during the daytime and
sleep at night, so shift workers struggle to stay alert and experience problems on the
job. Many traffic accidents occur at night, as drivers sometimes take brief
microsleeps while driving. A brief nap or a cup of coffee can help drivers stay awake.
The Stages of Sleep
Sleep follows a cycle of distinct stages: presleep; stages 1 to 4 of deepening
sleep, as the body relaxes and brain waves become larger and slower; and REM
sleep, characterized by rapid eye movements, increased pulse rate, brain waves like
those of presleep, and totally relaxed muscles. It is during REM sleep that vivid
dreams occur. Each night, as we pass through several cycles, we gradually spend
more time in REM sleep and less time in non-REM, or NREM, sleep.
Why Do We Sleep?
Sleep is so necessary that when people try to stay awake for long periods, they
fall into short microsleeps, a few seconds at a time. According to restoration theory,
sleep helps us recover from the day’s demands. Circadian theory offers an
evolutionary explanation: Sleep helps animals conserve energy and avoid predators
when not searching for food or seeking a mate. Individuals differ in the amount of
sleep they require.
Dreams
https://t.me/medicina_free
Dreams, too, serve an adaptive function. As shown by studies that measure REM
sleep, people do most of their dreaming early in life when the brain is still developing.
Common themes include falling and being chased or attacked. Both daily concerns
and external stimuli also influence dream content. Some people experience lucid
dreaming, a semiconscious state in which they are aware of—and can control—their
own dreams.
Freud accounted for the bizarreness of dreams by theorizing that they are
disguised expressions of unconscious wishes. To interpret dreams, he said, one has
to go beyond the manifest content to uncover the unconscious meaning, or latent
content. A more recent hypothesis, the activation-synthesis theory, contends that
dreams begin with random neural signals in the brainstem. These signals spread up
to the cortex, and the brain tries to make sense of them by constructing images and
stories.
Sleep Disturbances
Sleep disturbances are common. Insomnia—the inability to fall asleep, stay
asleep, or get enough sleep—has many causes and can be cured through behavioral
means. Hypersomnia (sleeping too much) is less frequent but more dangerous,
particularly among those with narcolepsy, a disorder that causes sudden attacks of
REM sleep during the day. There are other serious sleep disturbances, or
parasomnias. People with sleep apnea snore loudly and repeatedly stop breathing
during sleep and awaken gasping for air. REM sleep behavior disorder (RBD) is a
condition in which the skeletal muscles are not paralyzed during REM sleep, enabling
sleepers to act on their nightmares, often violently. Other problems include night
terrors and sleepwalking.
Hypnosis
The Seeds of Controversy
Hypnosis is a set of attention-focusing procedures in which changes in a
subject’s behavior or mental state are suggested. It has a long and controversial
history in psychology.
The Hypnotic Induction
In the first stage of hypnosis, induction, the subject’s attention is focused. In the
second stage, suggestion, the subject responds to the hypnotist’s cues.
Hypnotic Responsiveness
People differ in their degree of hypnotic susceptibility, or responsiveness.
Those who are most responsive tend to have vivid imaginations and long attention
spans.
The Myths and Realities
Contrary to myth, people cannot be hypnotized against their will or be coerced
into violating their consciences. Evidence suggests, however, that hypnotized
subjects may shed their inhibitions. Hypnosis can reduce pain. Through
posthypnotic suggestion, the hypnotist can influence a subject’s behavior even
after the session ends. Posthypnotic amnesia is also common, though not
permanent. But hypermnesia, the supposed enhancement of a witness’s memory by
hypnosis, has not been confirmed in experiments. Rather, hypnosis makes witnesses
more vulnerable to false memories.
Is Hypnosis an “Altered” State?
Special-process theories maintain that hypnosis induces a unique state of
suggestibility. According to one theory, the hypnosis subject experiences
dissociation, a division of consciousness in which one part of the mind operates
independent of another. Social-psychological theories see hypnosis as an ordinary
state in which changes are produced by conscious faking or by processes of social
influence. To some extent, both theories may be true.
Consciousness-Altering Drugs
Throughout history, people have sought altered states of consciousness, often by
using consciousness-altering psychoactive drugs, chemicals that change
perceptions, moods, thoughts, or behavior. Such drugs are addictive, creating either
physical dependence or psychological dependence.
Sedatives
https://t.me/medicina_free
Among psychoactive drugs, sedatives such as alcohol, barbiturates, and
benzodiazepines slow activity in the central nervous system. Alcohol was the first and
is one of the most widely used drugs in the world.
Stimulants
Stimulants, including caffeine, nicotine, amphetamines, and cocaine, excite the
central nervous system and energize behavior. They can be addictive.
Hallucinogens
Hallucinogens, or psychedelic drugs, such as LSD and marijuana, distort
perceptions and can cause hallucinations.
Opiates
The highly addictive opiates, such as heroin, morphine, and codeine, depress
neural activity, relieve pain, and produce euphoria.
Consciousness and Control
As studies of attention and hypnosis illustrate, people have a great deal of
command over their own consciousness. Yet there are times when our minds wander
and we cannot control the distractions. Often we must contend with an irony: The
harder we try to manage our thoughts, the less likely we are to succeed.
Critical Thinking
Thinking Critically About Consciousness
1. Is hypnosis an altered state of consciousness? Compare the special-process
and social-psychological answers to this question. Which do you find more
compelling?
2. In what ways are we influenced by subliminal stimuli (i.e., stimuli presented
below the level of conscious awareness)? Why might people continue to believe
in the power of subliminal advertising?
3. Consider your cultural identity. Try to recall dreams that you’ve had, whether
recently or in the past. How might your culture influence the nature of your
dreams and what you dream about?
4. How can we use the concept of lucid dreaming to help people effectively deal
with nightmares?
Career Connection: Research
Psychological Technician
A psychological technician administers routine tests, helping patients under the
supervision of a psychologist. They may work with populations such as the elderly,
patients who have been psychiatrically hospitalized, and individuals with
developmental disabilities, often in hospitals or group residential settings. Daily
responsibilities include observing patients and helping them with daily activities,
providing updates to physicians and other providers, and documenting patients’
conditions in their medical records. Psychiatric technicians may also be responsible
for administering therapeutic aid and medications. The understanding of psychology
and human behavior developed during undergraduate study is directly applicable in
this role, which may also require certification courses or continuing education while
employed.
Key skills for this role that psychology students learn to develop:
Effective communication in presentations and written works
Self-efficacy and self-regulation
Ethical standards and multicultural value application
Key Terms
activation-synthesis theory (p. 148)
attention (p. 133)
biological rhythms (p. 137)
circadian rhythm (p. 137)
cocktail party phenomenon (p. 133)
consciousness (p. 133)
dissociation (p. 159)
divided attention (p. 135)
hallucinogens (p. 165)
hypermnesia (p. 157)
https://t.me/medicina_free
hypnosis (p. 154)
hypnotic susceptibility (p. 155)
insomnia (p. 149)
latent content (p. 148)
lucid dreaming (p. 148)
manifest content (p. 148)
microsleeps (p. 140)
narcolepsy (p. 151)
NREM sleep (p. 143)
opiates (p. 166)
physical dependence (p. 163)
posthypnotic amnesia (p. 157)
posthypnotic suggestion (p. 156)
priming (p. 136)
psychoactive drug (p. 162)
psychological dependence (p. 163)
REM sleep (p. 143)
REM sleep behavior disorder (RBD) (p. 152)
sedatives (p. 163)
selective attention (p. 134)
sleep apnea (p. 152)
stimulants (p. 165)
Stroop test (p. 135)
subliminal messages (p. 136)
Descriptions of Images and Figures
Back to Figure
An author introduction reads as follows. Shown here are drawings of the two
videotapes, left and center, and the resulting superimposed image on the right.
Subjects who were focused on the basketball players did not see the hand slappers,
and vice versa.
Image 1 contains a line drawing of a close-up of two pairs of hands, one pair
resting on top of the other, open palms pressed together.
Image 2 contains a line drawing of 3 people playing basketball.
Image 3 contains Image 1 superimposed over Image 2.
Back to Figure
An author introduction reads as follows. Each dark bar indicates the timing and
length of sleep during a day. During the unscheduled period, without time cues, the
subject’s activity assumed a 25-hour rhythm and began to advance around the clock.
When light-dark periods were scheduled, he resumed a normal sleep and activity
rhythm.
The Gantt-style chart records 11 sessions of unscheduled, free running rhythm
sleep and 10 sessions of scheduled light-dark cycle sleep. The initial unscheduled
sessions resulted in the individual tending to go to sleep a little later and to wake up a
little later based on each successive cycle. The number of hours sleep remained
broadly the same.
When the light-dark periods were re-introduced the subject resumed a normal
sleep pattern, broadly going to sleep at the same time around midnight and sleeping
for a similar number of hours.
Back to Figure
An author introduction reads as follows. In sleep laboratories, researchers record
brain-wave activity, eye movements, and muscle tension by taping electrodes to the
scalp, near the eyes, and elsewhere on the face.
There are 3 illustrations of a human head as follows.
1. Image 1. A human head is shown in profile. Electrodes are attached to the
temple, the chin, the throat, and the scalp.
2. Image 2. A human head is shown from above. Electrodes are attached to the
scalp, above each ear, the forehead, and the temples.
3. Image 3. A human head is shown from the front, with the head tilted back to
reveal the throat. Electrodes are attached to the temples, the chin, and the
throat.
The measurements taken are as follows.
E, E, G brain waves through the electrodes attached to the scalp.
Left eye movements through the electrodes attached to the left temple.
Right eye movements through the electrodes attached to the right temple.
https://t.me/medicina_free
E, M, G muscle tension through the electrodes attached to the chin and
throat.
Back to Figure
An author introduction reads as follows. As recorded by the EEG, brain waves get
larger and slower as sleep deepens from stages 1 to 4. As illustrated, REM sleep
waves closely resemble those of the pre-sleep state.
The 6 E, E, G outputs from the 6 stages of sleep are as follows.
1. Awake. The E, E, G output is fast, random, and low voltage at around 50
microvolts.
2. Drowsy, relaxed. The E, E, G outputs are alpha waves.
3. Stage 1 sleep. The E, E, G outputs are theta waves. The initial stages of
stage 1 sleep produces alpha waves, which are relatively low frequency, around
8 to 13 hertz, high amplitude patterns of electrical wave activity that become
synchronized. This pattern of brain wave activity resembles that of someone who
is very relaxed, yet awake.
4. Stage 2 sleep. The E, E, G outputs are sleep spindles and K complexes. The
body is in a state of deep relaxation. Sleep spindles are brief, powerful bursts of
synchronous neuronal firing in thalamocortical networks. K complexes are
transient events that consist of an initial negative sharp wave that is immediately
followed by a positive wave lasting greater than or equal to 0.5 seconds.
5. Stage 3 and Stage 4 sleep. The E, E, G outputs are slow wave sleep. This is
non-rapid eye movement, deep sleep. Stage 3 has 20 to 50 percent delta wave
activity, and Stage 4 has more than 50 percent delta wave activity.
6. REM sleep. The E, E, G output is fast and random. REM sleep is marked by
rapid movements of the eyes. The brain waves associated with this stage of
sleep are very similar to those observed when a person is awake.
Back to Figure
An author introduction reads as follow. People pass through four to six 90-minute
sleep cycles per night. As shown, progressively more time is spent in REM sleep and
progressively less is spent in the deeper stages.
The time since sleep onset is plotted on the X-axis, with a range from 12pm to
7am. The stages of sleep are plotted on the Y-axis. These include Stages 1 to 4 and
REM sleep.
The data points are presented in the following table.
Back to Figure
An author introduction reads as follows. Studies each year show the same
unfortunate outcome that Americans generally do not prioritize sleep.
The data points are presented in the following table.
Back to Figure
An author introduction reads as follows. Observations support the hypothesis that
sleep is an adaptive response to feeding and safety needs.
The 9 species types are plotted against the X-axis. Each species is illustrated with
an example that sits above the data bar. The number of hours of sleep is plotted
against the Y-axis. The data points are presented in the following table.
Back to Figure
An author introduction reads as follows. Many people report common recurring
dreams. Indeed, Americans tend to have many recurring dreams in common.
The 9 types of recurring and single dreams are plotted on the X-axis. The
percentage of dream content is plotted on the Y-axis, with a range from zero to 50, at
intervals of 5.
The data points are presented in the following table.
Back to Figure
An author note reads as follows. In this study, 58 people with insomnia received a
self-help program, additional care from a therapist, or no treatment. As shown, all
treatment subjects, whether or not they had a therapist, took less time to fall asleep
after the program than before it. With guidance, people can help themselves to
overcome insomnia.
The types of treatment are plotted on the X-axis with data points for before
treatment and after treatment. The number of minutes to fall asleep are plotted on the
Y-axis.
The data points are presented in the following table.
Back to Figure
An author introduction reads as follows. After observing a staged crime, subjects
were questioned in a hypnotized or waking state by an examiner who suggested that
https://t.me/medicina_free
the culprit had worn a mask. Under hypnosis, many subjects, particularly those high
in responsiveness, later incorporated this false suggestion into memory.
The level of hypnotic responsiveness is plotted on the X-axis. The percentage of
people that recalled seeing a mask are plotted on the Y-axis. The data points are
presented in the following table.
Back to Figure
An author introduction reads as follows. Subjects immersed a hand in ice water
and rated the pain they felt. Those under hypnosis reported less pain than did control
subjects. But by pressing a key, they also indicated that a part of them, a hidden
observer, was aware of the pain.
The seconds in the ice water are plotted on the X-axis, with a range from zero to
45 seconds. The pain ratings are plotted on the Y-axis, with a range from zero to 2, at
increments of 2.
The data points for the experiment are presented in the following table.
Back to Figure
The data is based on past month substance use among people aged 12 or older.
The pie chart data is presented in the following table.
The number of people who partook of substances in the past month are then
broken out into a horizontal bar chart based on the type of substance. The number of
past month users are plotted on the horizontal Y-axis, with a range from zero to 150
million, at intervals of 50 million. The 11 substance types are plotted on the vertical Xaxis. The data points are presented in the following table.
https://t.me/medicina_free
5 LEARNING
iStock.com/Prostock-Studio
Learning Objectives
Define and explain the nature of nonassociative learning.
Describe how Pavlov’s work on classical conditioning influenced how
we understand learning.
Describe the principles of operant conditioning and how this type of
conditioning is applied today.
Summarize the process of observational learning and how this type of
learning is applied today.
WHAT’S YOUR PREDICTION: CAN PEOPLE LEARN
WITHOUT REALIZING IT?
The Situation
As you enter the laboratory reception area, you are met by an experimenter, taken
to a small room, and told that you will be taking part in a study of human memory.
Next you’re told that you’ll have 7 minutes to examine the following strings of letters
and that you should simply try to “learn and remember as much as you can.” Ready,
begin:
You look at these meaningless items one by one, trying to memorize. P-V-V. T-S-
X-S. You just keep repeating them under your breath. After 7 minutes, the
experimenter stops you. Time’s up. You can’t wait to write down what you remember
before you lose it—but the experimenter has other plans. The experimenter reveals
that the items were formed according to a set of rules, an “artificial grammar” if you
will, and wants to know whether you know what the rules are. As the experimenter
explains the test you’re about to take, you get a sinking feeling in the pit of your
stomach. “Uh-oh. There were rules? I wasn’t looking for rules!”
The test is straightforward. On slides, you’ll view 100 new items made up of the
same letters as before, one item per slide. Half the items will be grammatical
(according to the rules); half will not. For each one, you are to press a button marked
YES if you think the item is grammatical or NO if you think it’s not. You should also
rate your confidence in each judgment on a scale marked from 1 to 5. Oh, one more
thing: Your responses will be timed.
The presentation is turned on, the overhead lights are shut off, and you’ve got
your fingers on the buttons ready to go. First item: PTTTVPVS. It looks okay, as it
contains the usual letters, and all. But are these letters ordered in a way that fits the
grammar? “If I don’t know,” you ask, “should I just guess?” Instructed to respond to
every item, you press a button and state your confidence. The next one is PVTW.
Same routine. PVPS. SVPXTW. SXXVPS. Sometimes you answer quickly; at other
https://t.me/medicina_free
times, you stare at the screen for a while before making a response. By the 100th
slide, you’re ready for a cool drink and a nap.
Make a Prediction
How well do you think people fare in this task? What you are likely to find is that
many subjects shrug their shoulders in confusion. Based on what you’ve read, what
do you think is the average test score? If all you did was guess, you would get
roughly a 50 percent accuracy rate. If you came up with rules that were wrong, your
score could be lower. If you knew the right rules, you would do better. So, what is
your estimate, 10 percent? 30? 55? 90? What's your prediction:
The Results
For decades, cognitive psychologist Arthur Reber (1993) used experiments like
this one to study “implicit learning”—the tendency for people to acquire complex,
abstract concepts without awareness or intention. Consistently, Reber has found that
subjects cannot describe the grammar that they use to form the letter strings, nor can
they explain the reasons for their YES and NO judgments. Yet in the study just
described, subjects made the correct response 77 percent of the time—and usually
did so quickly. How well do you think you would perform in this experiment?
What Does It All Mean?
Implicit learning, which occurs without our awareness, is a primitive but powerful
form of adaptation. Indeed, people learn this grammar not by actively searching for
rules or by receiving explicit instruction but simply through exposure to properly
formed letter strings. Without really trying, subjects learn the grammar the way we
learn to speak in our native tongue, figure out how to behave properly in a new
setting, or “calculate” the trajectory of a ball in flight in order to make the catch.
Implicit mental processes such as these are common (Cleeremans, Allakhverdov, &
Kuvaldina, 2019; Reber, 2013). To learn from experience, as the subjects did in this
study, people must be attuned to associations between stimuli in their environment
and between behavior and its consequences. As we’ll learn in this chapter,
association is the basic building block for all learning.
In many ways, learning is the foundation on which we adapt, change, grow,
advance, create, innovate, and at the most basic level, survive. We can learn in a
moment in time (such as what you are learning now by reading these words), over
the course of time (such as what you will have learned once you’ve finished this
book), at different points in time (such as what you learn in each term or college
semester), and even over evolutionary time (such as humans’ formulation of written
and spoken language as a species). Consider your own life, for example. Have your
experiences changed the emotions you feel for someone (such as feelings of love)?
The habits you developed (such as when you choose to go to sleep)? The foods you
prefer (such as foods common in your culture)? Your personality (such as your
tendencies to trust others or experience new things)? Possibly even the major you
chose in college (maybe influenced by your caregivers, what you got excited about in
school, or inspired by a teacher)? In this spirit, learning is not only a lifelong
endeavor; it is a process. In this chapter, we introduce two foundational processes for
how we learn: nonassociative and associative learning.
NONASSOCIATIVE LEARNING
LEARNING OBJECTIVES
Define and explain the nature of nonassociative learning.
Explain what fixed action patterns are, and identify some examples.
Relate some examples of fixed action patterns, and discuss whether humans
display them.
Define habituation, and explain how it is relevant to human behavior.
Every spring, a tiny freshwater fish called the stickleback performs an intriguing
reproductive ritual. As the male’s belly turns from dull gray to a bright red, he builds a
nest and does a zigzag courtship “dance” to attract a female stickleback, sometimes
brushing her belly with his stickles. He then escorts her to the nest, prods her tail to
induce spawning, fertilizes her eggs, aerates the eggs by fanning the water, and
vigorously attacks all red-bellied male intruders. Once the eggs hatch a week later, he
guards the young and keeps them close by until they are ready to leave the nest.
https://t.me/medicina_free
Many land animals also exhibit adaptive, complex forms of behavior. When the
herring-gull mother returns to the nest with food, newly hatched chicks peck at a red
spot on the mother’s bright yellow bill, causing her to regurgitate the food for their
consumption. The honeybee uses a wax it secretes to build hives in which each
comb consists of hexagonal cells that form a mathematically efficient, perfect design.
The indigo bunting, a small bird, navigates south every winter, using as a guide the
bright North Star, the only star in the Northern Hemisphere that maintains a fixed
compass position through the night. Similarly prepared by instinct, the canary sings,
the spider weaves its web, the beaver builds dams, and the newly hatched duckling
follows the first moving object it sees, usually its mother. How do the stickleback and
others know what to do? Simple. In many animal species, certain behaviors are
programmed by instinct.
Programmed by instinct, indigo buntings navigate south each winter, guided by
the light of the North Star.
iStock.com/SteveByland
Fixed Action Patterns
Inspired by Darwin’s theory of evolution and led by Nobel Prize winners Konrad
Lorenz and Nikolaas Tinbergen, ethologists study the behavior of animals in their
natural habitats (Alcock, 1997; Cate, 2009; Cate et al., 2009). Based on their
observations, these researchers refer to the instinctual behaviors as fixed action
patterns. A fixed action pattern is a species-wide sequence of movements that is
built into the nervous system and triggered or “released” by a specific stimulus. The
response to the stimulus is automatic, like a reflex—no ifs, ands, or buts. Thus, the
stickleback male attacks all red-bellied forms, even those that do not resemble a fish
(illustrated in Figure 5.1). Similarly, the herring-gull chick pecks at all moving red dots
(a begging response to the red spot on the parental bill for feeding), even if the dot is
not on another bird.
ethologists. Scientists who study the behavior of animals in their natural habitats.
fixed action pattern. A species-specific behavior that is built into an animal’s
nervous system and triggered by a specific stimulus.
You may notice that fixed action patterns are a bit unusual in that a fixed response
is, well, fixed; it cannot change, whereas a flexible response is generally more
adaptive to change. In essence, these behaviors tend to be essential to an animal’s
survival. Behaviors that are essential to survival are those such as courting or mating
(e.g., the stickleback male attacks all red-bellied forms of fish that enter his territory
while a sexually receptive female is present), and maternal behavior (e.g., the greylag
goose’s egg-rolling behavior is essential to the survival of its chicks). Certainly these
responses can be exploited, such as when the herring-gull chick pecks at all moving
red dots. Such behavior is essential to survival—in terms of feeding behavior in the
herring-gull’s case.
Do people exhibit fixed action patterns? Are we instinctual creatures? We’ll find
later that human newborns are equipped with adaptive, instinctlike behaviors in the
form of reflexes. Upon birth, an infant will clutch anything that touches the palm of the
hand, turn with an open mouth toward any object that grazes the cheek, start sucking
when the lips are touched, and swallow when the back of the mouth is stimulated.
These reflexes are not within the infant’s control, and some disappear within a few
https://t.me/medicina_free
Соседние файлы в папке Библиотека им академика М.И. Перельмана