In psychology and ethology, imprinting is any kind of phase-sensitive learning
(learning occurring at a particular age or a particular life stage)
that is rapid and apparently independent of the consequences of
behaviour. It was first used to describe situations in which an animal
or person learns the characteristics of some stimulus, which is
therefore said to be "imprinted" onto the subject. Imprinting is
hypothesized to have a critical period.
Filial imprinting
The best-known form of imprinting is filial imprinting,
in which a young animal narrows its social preferences to an object
(typically a parent) as a result of exposure to that object. It is most
obvious in nidifugous birds, which imprint on their parents and then follow them around. It was first reported in domestic chickens, by Sir Thomas More in 1516 as described in his treatise Utopia, 350 earlier than by the 19th-century amateur biologist Douglas Spalding. It was rediscovered by the early ethologist Oskar Heinroth, and studied extensively and popularized by his disciple Konrad Lorenz working with greylag geese.
Lorenz demonstrated how incubator-hatched geese would imprint on
the first suitable moving stimulus they saw within what he called a "critical period"
between 13–16 hours shortly after hatching. For example, the goslings
would imprint on Lorenz himself (to be more specific, on his wading
boots), and he is often depicted being followed by a gaggle of geese
who had imprinted on him. Lorenz also found that the geese could
imprint on inanimate objects. In one notable experiment, they followed a
box placed on a model train in circles around the track. Filial imprinting is not restricted to non-human animals that are able to follow their parents, however.
The filial imprinting of birds was a primary technique used to create the movie Winged Migration (Le Peuple Migrateur),
which contains a great deal of footage of migratory birds in flight.
The birds imprinted on handlers, who wore yellow jackets and honked
horns constantly. The birds were then trained to fly along with a
variety of aircraft, primarily ultralights.
Imprinted geese and cranes flying with an ultralight aircraft
The Italian hang-glider pilot Angelo d'Arrigo extended this technique. D'Arrigo noted that the flight of a non-motorised hang-glider
is very similar to the flight patterns of migratory birds; both use
updrafts of hot air (thermal currents) to gain altitude that then
permits soaring flight over distance. He used this to reintroduce threatened species of raptors.
Because birds hatched in captivity have no mentor birds to teach them
traditional migratory routes, D'Arrigo hatched chicks under the wing of
his glider and imprinted on him. Then, he taught the fledglings to fly
and to hunt. The young birds followed him not only on the ground (as
with Lorenz) but also in the air as he took the path of various
migratory routes. He flew across the Sahara and over the Mediterranean Sea to Sicily with eagles, from Siberia to Iran (5,500 km) with a flock of Siberian cranes, and over Mount Everest with Nepalese eagles. In 2006, he worked with a condor in South America.
In a similar project, orphaned Canada geese were trained to their normal migration route by the Canadian ultralight enthusiast Bill Lishman, as shown in the fact-based movie drama Fly Away Home.
Chicks of domestic chickens
prefer to be near large groups of objects that they have imprinted on.
This behaviour was used to determine that very young chicks of a few
days old have rudimentary counting skills. In a series of experiments,
they were made to imprint on plastic balls and could figure out which of
two groups of balls hidden behind screens had the most balls.
American coot
mothers have the ability to recognize their chicks by imprinting on
cues from the first chick that hatches. This allows mothers to
distinguish their chicks from parasitic chicks.
The peregrine falcon
has also been known to imprint on specific structures for their
breeding grounds such as cliff sides and bridges and thus will favour
that location for breeding.
Sexual imprinting
Sexual imprinting is the process by which a young animal learns the characteristics of a desirable mate. For example, male zebra finches
appear to prefer mates with the appearance of the female bird that
rears them, rather than that of the birth parent when they are
different.
Sexual attraction to humans can develop in non-human mammals or
birds as a result of sexual imprinting when reared from young by humans.
One example is London Zoo female giant pandaChi Chi. When taken to Moscow Zoo for mating with the male giant panda An An, she refused his attempts to mate with her, but made a full sexual self-presentation to a zookeeper.
It commonly occurs in falconry
birds reared from hatching by humans. Such birds are called "imprints"
in falconry. When an imprint must be bred from, the breeder lets the
male bird copulate with their head while they are wearing a special hat
with pockets on to catch the male bird's semen. The breeder then courts a suitable imprint female bird (including offering food, if it is part of that species's normal courtship).
At "copulation," the breeder puts the flat of one hand on the female
bird's back to represent the weight of a male bird, and with the other
hand uses a pipette, or a hypodermic syringe without a needle, to squirt the semen into the female's cloaca.
Sexual imprinting on inanimate objects is a popular theory concerning the development of sexual fetishism. For example, according to this theory, imprinting on shoes or boots (as with Konrad Lorenz's geese) would be the cause of shoe fetishism.
Limbic imprinting
Some suggest that prenatal, perinatal and post-natal experiences leave imprints upon the limbic system, causing lifelong effects and this process is identified as limbic imprinting.
The term is also described as the human emotional map, deep-seated
beliefs, and values that are stored in the brain's limbic system and
govern people's lives at the subconscious level.
It is one of the suggested explanations for the claim that the
experiences of an infant, particularly during the first two years of his
life, contribute to his lifelong psychological development.
Imprinted genes can have astounding effects on body size, brain size,
and the process in which the brain organizes its processes. Evolutionary
trends within the animal kingdom have been shown to show substantive
increase in the fore-brain particularly towards the limbic system, this evolution has even been through of to have a mutative effect on the brain size trickling down the human ancestry.
Westermarck effect
Reverse sexual imprinting is also seen in instances where two
people who live in domestic proximity during the first few years in the
life of either one become desensitized to later close sexual attraction. This phenomenon, known as the Westermarck effect, was first formally described by FinnishanthropologistEdvard Westermarck in his book The History of Human Marriage (1891). The Westermarck effect has since been observed in many places and cultures, including in the Israelikibbutz system, and the Chinese shim-pua marriage customs, as well as in biological-related families.
In the case of the Israeli kibbutzim (collective farms), children
were reared somewhat communally in peer groups, based on age, not
biological relation. A study of the marriage patterns of these children
later in life revealed that out of the nearly 3,000 marriages that
occurred across the kibbutz system, only fourteen were between children
from the same peer group. Of those fourteen, none had been reared
together during the first six years of life. This result provides
evidence not only that the Westermarck effect is demonstrable but that
it operates during the period from birth to the age of six. However, Eran Shor and Dalit Simchai claimed that the case of the kibbutzim actually provides little support for the Westermarck effect.
When proximity during this critical period
does not occur—for example, where a brother and sister are brought up
separately, never meeting one another—they may find one another highly
sexually attractive when they meet as adults. This phenomenon is known as genetic sexual attraction. This observation supports the hypothesis that the Westermarck effect evolved because it suppressed inbreeding. This attraction may also be seen with cousin couples.
Sigmund Freud
argued that as children, members of the same family naturally lust for
one another, making it necessary for societies to create incest taboos, but Westermarck argued the reverse, that the taboos themselves arise naturally as products of innate attitudes. Steven Pinker
has written that Freud's conception of an urge to incest may have
derived from Freud's own erotic reaction to his mother as a boy
(attested in Freud's own writings), and speculates that Freud's reaction
may have been due to lack of intimacy with his mother in early
childhood, as Freud was wet-nursed.
Baby duck syndrome
Ducklings following their mother.
In human–computer interaction, baby duck syndrome
denotes the tendency for computer users to "imprint" on the first
system they learn, then judge other systems by their similarity to that
first system. The result is that "users generally prefer systems similar to those they learned on and dislike unfamiliar systems".
The issue may present itself relatively early in a computer user's
experience, and it has been observed to impede education of students in
new software systems or user interfaces.
Lorenz studied instinctive behavior in animals, especially in greylag geese and jackdaws. Working with geese, he investigated the principle of imprinting, the process by which some nidifugous
birds (i.e. birds that leave their nest early) bond instinctively with
the first moving object that they see within the first hours of
hatching. Although Lorenz did not discover the topic, he became widely
known for his descriptions of imprinting as an instinctive bond. In
1936 he met Tinbergen, and the two collaborated in developing ethology
as a separate sub-discipline of biology. A Review of General Psychology
survey, published in 2002, ranked Lorenz as the 65th most cited scholar
of the 20th century in the technical psychology journals, introductory
psychology textbooks, and survey responses.
Lorenz wrote numerous books, some of which, such as King Solomon's Ring, On Aggression, and Man Meets Dog,
became popular reading. His last work "Here I Am – Where Are You?" is a
summary of his life's work and focuses on his famous studies of greylag
geese.
Biography
Lorenz in 1904 with his older brother
In his autobiographical essay, published in 1973 in Les Prix Nobel
(winners of the prizes are requested to provide such essays), Lorenz
credits his career to his parents, who "were supremely tolerant of my
inordinate love for animals", and to his childhood encounter with Selma Lagerlöf's The Wonderful Adventures of Nils, which filled him with a great enthusiasm about wild geese. "
At the request of his father, Adolf Lorenz, he began a premedical curriculum in 1922 at Columbia University, but he returned to Vienna in 1923 to continue his studies at the University of Vienna.
He graduated as Doctor of Medicine (MD) in 1928 and became an assistant
professor at the Institute of Anatomy until 1935. He finished his
zoological studies in 1933 and received his second doctorate (PhD).
While still a student, Lorenz began developing what would become a large menagerie, ranging from domestic to exotic animals. In his popular book King Solomon's Ring,
Lorenz recounts that while studying at the University of Vienna he kept
a variety of animals at his parents' apartment, ranging from fish to a capuchin monkey named Gloria.
In 1936, at an international scientific symposium on instinct, Lorenz met his great friend and colleague Nikolaas Tinbergen. Together they studied geese—wild, domestic, and hybrid.
One result of these studies was that Lorenz "realized that an
overpowering increase in the drives of feeding as well as of copulation
and a waning of more differentiated social instincts is characteristic
of very many domestic animals". Lorenz began to suspect and fear "that
analogous processes of deterioration may be at work with civilized
humanity." This observation of bird hybrids caused Lorenz to believe
that domestication resulting from urbanisation in humans might also
cause dysgenic effects, and to argue in two papers that the Nazi eugenics policies against this were therefore scientifically justified.
In 1940 he became a professor of psychology at the University of Königsberg. He was drafted into the Wehrmacht
in 1941. He sought to be a motorcycle mechanic, but instead he was
assigned as a military psychologist, conducting racial studies on humans
in occupied Poznań under Rudolf Hippius.
The objective was to study the biological characteristics of
"German-Polish half-breeds" to determine whether they 'benefitted' from
the same work ethics as 'pure' Germans.
The degree to which Lorenz participated in the project is unknown, but
the project director Hippius referred a couple of times to Lorenz as an
"examining psychologist".
Lorenz later described that he once saw transports of concentration camp inmates at Fort VII near Poznań, which made him "fully realize the complete inhumanity of the Nazis".
He was sent to the Russian front in 1944 where he quickly became a prisoner of war in the Soviet Union
from 1944 to 1948. In captivity he continued to work as a medic and
"got quite friendly with some Russians, mostly doctors". When he was
repatriated, he was allowed to keep the manuscript of a book he had been
writing, and his pet starling.
He arrived back in Altenberg (his family home, near Vienna) both "with
manuscript and bird intact." The manuscript became his 1973 book Behind the Mirror.
The Max Planck Society established the Lorenz Institute for Behavioral Physiology in Buldern, Germany,
in 1950. In his memoirs Lorenz described the chronology of his war
years differently from what historians have been able to document after
his death. He himself claimed that he was captured in 1942, where in
reality he was only sent to the front and captured in 1944, leaving out
entirely his involvement with the Poznań project.
He retired from the Max Planck Institute in 1973 but continued to research and publish from Altenberg and Grünau im Almtal in Austria. He died on 27 February 1989 in Altenberg.
Ethology
Lorenz is recognized as one of the founding fathers of the field of ethology, the study of animal behavior. He is best known for his discovery of the principle of attachment, or imprinting,
through which in some species a bond is formed between a new born
animal and its caregiver. This principle had been discovered by Douglas Spalding in the 19th century, and Lorenz's mentor Oskar Heinroth had also worked on the topic, but Lorenz's description of Prägung, imprinting, in nidifugous birds such as greylag geese in his 1935 book Der Kumpan in der Umwelt des Vogels ("The Companion in the Environment of Birds") became the foundational description of the phenomenon.
Here, Lorenz used Jakob von Uexküll's concept of Umwelt
to understand how the limited perception of animals filtered out
certain phenomena with which they interacted instinctively. For example,
a young goose instinctively bonds with the first moving stimulus it
perceives, whether it be its mother, or a person. Lorenz showed that
this behavior of imprinting
is what allows the goose to learn to recognize members of its own
species, enabling them to be the object of subsequent behavior patterns
such as mating.
He developed a theory of instinctive behavior that saw behavior
patterns as largely innate but triggered through environmental stimuli,
for example the hawk/goose effect.
He argued that animals have an inner drive to carry out instinctive
behaviors, and that if they do not encounter the right stimulus they
will eventually engage in the behavior with an inappropriate stimulus.
Lorenz's approach to ethology derived from a skepticism towards
the studies of animal behavior done in laboratory settings. He
considered that in order to understand the mechanisms of animal
behavior, it was necessary to observe their full range of behaviors in
their natural context. Lorenz did not carry out much traditional
fieldwork but observed animals near his home. His method involved
empathizing with animals, often using anthropomorphization to imagine
their mental states. He believed that animals were capable of
experiencing many of the same emotions as humans.
Tinbergen, Lorenz's friend with whom he conjointly received the
Nobel prize, summarized Lorenz's major contribution to ethology as
making behavior a topic of biological inquiry, considering behavior a
part of an animal's evolutionary equipment.
Tinbergen and Lorenz contributed to making Ethology a recognized
sub-discipline within Biology and founded the first specialized journal
of the field "Ethology" (originally "Zeitschift für Tierpsychologie").
Politics
Lorenz joined the Nazi Party in 1938 and accepted a university chair under the Nazi regime.
In his application for party membership he wrote, "I'm able to say that
my whole scientific work is devoted to the ideas of the National Socialists."
His publications during that time led in later years to allegations
that his scientific work had been contaminated by Nazi sympathies. His
published writing during the Nazi period included support for Nazi ideas
of "racial hygiene" couched in pseudoscientific metaphors.
In his autobiography, Lorenz wrote:
I was frightened—as I still am—by the thought that
analogous genetical processes of deterioration may be at work with
civilized humanity. Moved by this fear, I did a very ill-advised thing
soon after the Germans had invaded Austria: I wrote about the dangers of
domestication and, in order to be understood, I couched my writing in the worst of Nazi terminology. I do not want to extenuate this action. I did, indeed, believe that some good might come of the new rulers. The precedent narrow-minded catholic regime
in Austria induced better and more intelligent men than I was to
cherish this naive hope. Practically all my friends and teachers did so,
including my own father who certainly was a kindly and humane man. None
of us as much as suspected that the word "selection", when used by
these rulers, meant murder. I regret those writings not so much for the
undeniable discredit they reflect on my person as for their effect of
hampering the future recognition of the dangers of domestication.
After the war, Lorenz denied having been a party member,
until his membership application was made public; and he denied having
known the extent of the genocide, despite his position as a psychologist
in the Office of Racial Policy. He was also shown to have made anti-Semitic jokes on 'Jewish characteristics' in letters to his mentor Heinroth. In 2015 the University of Salzburg
posthumously rescinded an honorary doctorate awarded to Lorenz in 1983,
citing his party membership and his assertions in his application that
he was "always a National Socialist", and that his work "stands to serve
National Socialist thought". The university also accused him of using
his work to spread "basic elements of the racist ideology of National
Socialism".
During the final years of his life, Lorenz supported the fledgling Austrian Green Party and in 1984 became the figurehead of the Konrad Lorenz Volksbegehren, a grass-roots movement that was formed to prevent the building of a power plant at the Danube near Hainburg an der Donau and thus the destruction of the surrounding woodland.
Lorenz has been called 'The father of ethology', by Niko Tinbergen.
Perhaps Lorenz's most important contribution to ethology was his idea
that behavior patterns can be studied as anatomical organs. This concept forms the foundation of ethological research. However, Richard Dawkins called Lorenz a "'good of the species' man", stating that the idea of group selection was "so deeply ingrained" in Lorenz's thinking that he "evidently did not realize that his statements contravened orthodox Darwinian theory."
Together with Nikolaas Tinbergen, Lorenz developed the idea of an innate releasing mechanism to explain instinctive behaviors (fixed action patterns). They experimented with "supernormal stimuli"
such as giant eggs or dummy bird beaks which they found could release
the fixed action patterns more powerfully than the natural objects for
which the behaviors were adapted. Influenced by the ideas of William McDougall, Lorenz developed this into a "psychohydraulic" model of the motivation of behavior, which tended towards group selectionist ideas, which were influential in the 1960s. Another of his contributions to ethology is his work on imprinting. His influence on a younger generation of ethologists; and his popular works, were important in bringing ethology to the attention of the general public.
Lorenz claimed that there was widespread contempt for the
descriptive sciences. He attributed this to the denial of perception as
the source of all scientific knowledge: "a denial that has been elevated
to the status of religion."
He wrote that in comparative behavioral research, "it is necessary to
describe various patterns of movement, record them, and above all,
render them unmistakably recognizable."
Lorenz predicted the relationship between market economics and the threat of ecological catastrophe. In his 1973 book, Civilized Man's Eight Deadly Sins, Lorenz addresses the following paradox:
All the advantages that man has gained from his
ever-deepening understanding of the natural world that surrounds him,
his technological, chemical and medical progress, all of which should
seem to alleviate human suffering... tends instead to favor humanity's
destruction
Lorenz adopts an ecological model to attempt to grasp the mechanisms
behind this contradiction. Thus "all species... are adapted to their
environment... including not only inorganic components... but all the
other living beings that inhabit the locality." p31.
Fundamental to Lorenz's theory of ecology is the function of negative feedback
mechanisms, which, in hierarchical fashion, dampen impulses that occur
beneath a certain threshold. The thresholds themselves are the product
of the interaction of contrasting mechanisms. Thus pain and pleasure act
as checks on each other:
To gain a desired prey, a dog or wolf will do things
that, in other contexts, they would shy away from: run through thorn
bushes, jump into cold water and expose themselves to risks which would
normally frighten them. All these inhibitory mechanisms... act as a
counterweight to the effects of learning mechanisms... The organism
cannot allow itself to pay a price which is not worth paying. p53.
In nature, these mechanisms tend towards a 'stable state' among the living beings of an ecology:
A closer examination shows that these beings... not only
do not damage each other, but often constitute a community of interests.
It is obvious that the predator is strongly interested in the survival
of that species, animal or vegetable, which constitutes its prey. ... It
is not uncommon that the prey species derives specific benefits from
its interaction with the predator species... pp31–33.
Lorenz states that humanity is the one species not bound by these
mechanisms, being the only one that has defined its own environment:
[The pace of human ecology] is determined by the progress
of man's technology (p35)... human ecology (economy) is governed by
mechanisms of POSITIVE feedback, defined as a mechanism which tends to
encourage behavior rather than to attenuate it (p43). Positive feedback
always involves the danger of an 'avalanche' effect... One particular
kind of positive feedback occurs when individuals OF THE SAME SPECIES
enter into competition among themselves... For many animal species,
environmental factors keep... intraspecies selection from [leading to]
disaster... But there is no force which exercises this type of healthy
regulatory effect on humanity's cultural development; unfortunately for
itself, humanity has learned to overcome all those environmental forces
which are external to itself p44.
Regarding aggression in human beings, Lorenz states:
Let us imagine that an absolutely unbiased investigator
on another planet, perhaps on Mars, is examining human behavior on
earth, with the aid of a telescope whose magnification is too small to
enable him to discern individuals and follow their separate behavior,
but large enough for him to observe occurrences such as migrations of
peoples, wars, and similar great historical events. He would never gain
the impression that human behavior was dictated by intelligence, still
less by responsible morality. If we suppose our extraneous observer to
be a being of pure reason, devoid of instincts himself and unaware of
the way in which all instincts in general and aggression in particular
can miscarry, he would be at a complete loss how to explain history at
all. The ever-recurrent phenomena of history do not have reasonable
causes. It is a mere commonplace to say that they are caused by what
common parlance so aptly terms "human nature." Unreasoning and
unreasonable human nature causes two nations to compete, though no
economic necessity compels them to do so; it induces two political
parties or religions with amazingly similar programs of salvation to
fight each other bitterly, and it impels an Alexander or a Napoleon to
sacrifice millions of lives in his attempt to unite the world under his
scepter. We have been taught to regard some of the persons who have
committed these and similar absurdities with respect, even as "great"
men, we are wont to yield to the political wisdom of those in charge,
and we are all so accustomed to these phenomena that most of us fail to
realize how abjectly stupid and undesirable the historical mass behavior
of humanity actually is
Lorenz does not see human independence from natural ecological processes as necessarily bad. Indeed, he states that:
A completely new [ecology] which corresponds in every way
to [humanity's] desires... could, theoretically, prove as durable as
that which would have existed without his intervention (36).
However, the principle of competition, typical of Western societies, destroys any chance of this:
The competition between human beings destroys with cold
and diabolic brutality... Under the pressure of this competitive fury we
have not only forgotten what is useful to humanity as a whole, but even
that which is good and advantageous to the individual. [...] One asks,
which is more damaging to modern humanity: the thirst for money or
consuming haste... in either case, fear plays a very important role: the
fear of being overtaken by one's competitors, the fear of becoming
poor, the fear of making wrong decisions or the fear of not being up to
snuff... pp45–47.
In this book, Lorenz proposes that the best hope for mankind lies in
our looking for mates based on the kindness of their hearts rather than
good looks or wealth. He illustrates this with a Jewish story,
explicitly described as such.
Lorenz was one of the early scientists who recognised the significance of human overpopulation. The number one deadly sin of civilized man in his book is overpopulation, which is what leads to aggression.
Philosophical speculations
In his 1973 book Behind the Mirror: A Search for a Natural History of Human Knowledge,
Lorenz considers the old philosophical question of whether our senses
correctly inform us about the world as it is, or provide us only with an
illusion. His answer comes from evolutionary biology.
Only traits that help us survive and reproduce are transmitted. If our
senses gave us wrong information about our environment, we would soon be
extinct. Therefore, we can be sure that our senses give us correct
information, for otherwise we would not be here to be deceived.
Lorenz's best-known books are King Solomon's Ring and On Aggression, both written for a popular audience. His scientific work appeared mainly in journal articles, written in German; it became widely known to English-speaking scientists through its description in Tinbergen's 1951 bookThe Study of Instinct, though many of his papers were later published in English translation in the two volumes titled Studies in Animal and Human Behavior.
King Solomon's Ring (1949) (Er redete mit dem Vieh, den Vögeln und den Fischen, 1949)
Man Meets Dog (1950) (So kam der Mensch auf den Hund, 1950)
Evolution and Modification of Behaviour (1965)
On Aggression (1966) (Das sogenannte Böse. Zur Naturgeschichte der Aggression, 1963)
Studies in Animal and Human Behavior, Volume I (1970)
Studies in Animal and Human Behavior, Volume II (1971)
Motivation of Human and Animal Behavior: An Ethological View. With Paul Leyhausen (1973). New York: D. Van Nostrand Co. ISBN0-442-24886-5
Civilized Man's Eight Deadly Sins (1974) (Die acht Todsünden der zivilisierten Menschheit, 1973)
The Year of the Greylag Goose (1979) (Das Jahr der Graugans, 1979)
The Foundations of Ethology (1982)
The Waning of Humaneness (1987) (Der Abbau des Menschlichen, 1983)
Here I Am – Where Are You? – A Lifetime's Study of the Uncannily Human Behaviour of the Greylag Goose. (1988). Translated by Robert D. Martin from Hier bin ich – wo bist du?.
The Natural Science of the Human Species: An Introduction to
Comparative Behavioral Research – The Russian Manuscript (1944–1948) (1995)
A drawing of a cat by T. W. Wood in Charles Darwin's book The Expression of the Emotions in Man and Animals, described as acting "in an affectionate frame of mind".
Worldwide laws regarding the formal recognition of nonhuman animal sentience and suffering
1certain animals are excluded, only mental health is acknowledged, and/or the laws vary internally 2only includes domestic animals
Emotion is defined as any mental experience with high intensity and high hedonic content. The existence and nature of emotions in animals are believed to be correlated with those of humans and to have evolved from the same mechanisms. Charles Darwin
was one of the first scientists to write about the subject, and his
observational (and sometimes anecdotal) approach has since developed
into a more robust, hypothesis-driven, scientific approach. Cognitive bias tests and learned helplessness
models have shown feelings of optimism and pessimism in a wide range of
species, including rats, dogs, cats, rhesus macaques, sheep, chicks,
starlings, pigs, and honeybees. Jaak Panksepp
played a large role in the study of animal emotion, basing his research
on the neurological aspect. Mentioning seven core emotional feelings
reflected through a variety of neuro-dynamic limbic emotional action
systems, including seeking, fear, rage, lust, care, panic and play. Through brain stimulation and pharmacological challenges, such emotional responses can be effectively monitored.
Emotion has been observed and further researched through multiple
different approaches including that of behaviourism, comparative,
anecdotal, specifically Darwin's approach and what is most widely used
today the scientific approach which has a number of subfields including
functional, mechanistic, cognitive bias tests, self-medicating, spindle
neurons, vocalizations and neurology.
While emotions in animals is still quite a controversial topic it
has been studied in a extensive array of species both large and small
including primates, rodents, elephants, horses, birds, dogs, cats,
honeybees and crayfish.
Etymology, definitions, and differentiation
The word "emotion" dates back to 1579, when it was adapted from the French word émouvoir, which means "to stir up". However, the earliest precursors of the word likely date back to the very origins of language.
Emotions have been described as discrete and consistent responses
to internal or external events which have a particular significance for
the organism. Emotions are brief in duration and consist of a
coordinated set of responses, which may include physiological, behavioural, and neural mechanisms. Emotions have also been described as the result of evolution because they provided good solutions to ancient and recurring problems that faced ancestors.
Laterality
It
has been proposed that negative, withdrawal-associated emotions are
processed predominantly by the right hemisphere, whereas the left
hemisphere is largely responsible for processing positive,
approach-related emotions. This has been called the "laterality-valence hypothesis".
Basic and complex human emotions
In humans, a distinction is sometimes made between "basic" and "complex" emotions. Six emotions have been classified as basic: anger, disgust, fear, happiness, sadness and surprise. Complex emotions would include contempt, jealousy and sympathy. However, this distinction is difficult to maintain, and animals are often said to express even the complex emotions.
Prior to the development of animal sciences such as comparative psychology and ethology, interpretation of animal behaviour tended to favour a minimalistic approach known as behaviourism.
This approach refuses to ascribe to an animal a capability beyond the
least demanding that would explain a behaviour; anything more than this
is seen as unwarranted anthropomorphism.
The behaviourist argument is, why should humans postulate consciousness
and all its near-human implications in animals to explain some
behaviour, if mere stimulus-response is a sufficient explanation to produce the same effects?
Some behaviourists, such as John B. Watson, claim that stimulus–response models
provide a sufficient explanation for animal behaviours that have been
described as emotional, and that all behaviour, no matter how complex,
can be reduced to a simple stimulus-response association. Watson
described that the purpose of psychology was "to predict, given the
stimulus, what reaction will take place; or given the reaction, state
what the situation or stimulus is that has caused the reaction".
The cautious wording of Dixon exemplifies this viewpoint:
“
Recent work in the area of ethics
and animals suggests that it is philosophically legitimate to ascribe
emotions to animals. Furthermore, it is sometimes argued that
emotionality is a morally relevant psychological state shared by humans
and non-humans. What is missing from the philosophical literature that
makes reference to emotions in animals is an attempt to clarify and
defend some particular account of the nature of emotion, and the role
that emotions play in a characterization of human nature. I argue in
this paper that some analyses of emotion are more credible than others.
Because this is so, the thesis that humans and nonhumans share emotions
may well be a more difficult case to make than has been recognized thus
far.
”
Moussaieff Masson and McCarthy describe a similar view (with which they disagree):
“
While
the study of emotion is a respectable field, those who work in it are
usually academic psychologists who confine their studies to human
emotions. The standard reference work, The Oxford Companion to Animal Behaviour,
advises animal behaviourists that "One is well advised to study the
behaviour, rather than attempting to get at any underlying emotion.
There is considerable uncertainty and difficulty related to the interpretation and ambiguity
of emotion: an animal may make certain movements and sounds, and show
certain brain and chemical signals when its body is damaged in a
particular way. But does this mean an animal feels—is aware
of—pain as we are, or does it merely mean it is programmed to act a
certain way with certain stimuli? Similar questions can be asked of any
activity an animal (including a human) might undertake, in principle.
Many scientists regard all emotion and cognition (in humans and animals)
as having a purely mechanistic basis.
”
Because of the philosophical questions of consciousness and mind
that are involved, many scientists have stayed away from examining
animal and human emotion, and have instead studied measurable brain
functions through neuroscience.
In no case is an animal activity to be interpreted in terms of higher psychological processes, if it can be fairly interpreted in terms of processes which stand lower
in the scale of psychological evolution and development.
”
Darwin's approach
Charles Darwin initially planned to include a chapter on emotion in The Descent of Man but as his ideas progressed they expanded into a book, The Expression of the Emotions in Man and Animals.
Darwin proposed that emotions are adaptive and serve a communicative
and motivational function, and he stated three principles that are
useful in understanding emotional expression: First, The Principle of Serviceable Habits takes a Lamarckian stance by suggesting that emotional expressions that are useful will be passed on to the offspring. Second, The Principle of Antithesis suggests that some expressions exist merely because they oppose an expression that is useful. Third, The Principle of the Direct Action of the Excited Nervous System on the Body suggests that emotional expression occurs when nervous energy has passed a threshold and needs to be released.
Darwin saw emotional expression as an outward communication of an
inner state, and the form of that expression often carries beyond its
original adaptive use. For example, Darwin remarks that humans often
present their canine teeth when sneering in rage, and he suggests that
this means that a human ancestor probably utilized their teeth in
aggressive action. A domestic dog's simple tail wag may be used in subtly different ways to convey many meanings as illustrated in Darwin's The Expression of the Emotions in Man and Animals published in 1872.
Examples of tail position indicating different emotions in dogs
"Small dog watching a cat on a table"
"Dog approaching another dog with hostile intentions"
"Dog in a humble and affectionate frame of mind"
"Half-bred shepherd dog"
"Dog caressing his master"
Anecdotal approach
Evidence
for emotions in animals has been primarily anecdotal, from individuals
who interact with pets or captive animals on a regular basis. However,
critics of animals having emotions often suggest that anthropomorphism
is a motivating factor in the interpretation of the observed behaviours.
Much of the debate is caused by the difficulty in defining emotions and
the cognitive requirements thought necessary for animals to experience
emotions in a similar way to humans.
The problem is made more problematic by the difficulties in testing for
emotions in animals. What is known about human emotion is almost all
related or in relation to human communication.
Scientific approach
In
recent years, the scientific community has become increasingly
supportive of the idea of emotions in animals. Scientific research has
provided insight into similarities of physiological changes between
humans and animals when experiencing emotion.
Much support for animal emotion and its expression results from
the notion that feeling emotions doesn't require significant cognitive
processes,
rather, they could be motivated by the processes to act in an adaptive
way, as suggested by Darwin. Recent attempts in studying emotions in
animals have led to new constructions in experimental and information
gathering. Professor Marian Dawkins suggested that emotions could be
studied on a functional or a mechanistic basis. Dawkins suggests that
merely mechanistic or functional research will provide the answer on its
own, but suggests that a mixture of the two would yield the most
significant results.
Functional
Functional
approaches rely on understanding what roles emotions play in humans and
examining that role in animals. A widely used framework for viewing
emotions in a functional context is that described by Oatley and Jenkins
who see emotions as having three stages: (i) appraisal in which there
is a conscious or unconscious evaluation of an event as relevant to a
particular goal. An emotion is positive when that goal is advanced and
negative when it is impeded (ii) action readiness where the emotion
gives priority to one or a few kinds of action and may give urgency to
one so that it can interrupt or compete with others and (iii)
physiological changes, facial expression and then behavioural action.
The structure, however, may be too broad and could be used to include
all the animal kingdom as well as some plants.
Mechanistic
The
second approach, mechanistic, requires an examination of the mechanisms
that drive emotions and search for similarities in animals.
The mechanistic approach is utilized extensively by Paul, Harding
and Mendl. Recognizing the difficulty in studying emotion in non-verbal
animals, Paul et al. demonstrate possible ways to better examine this.
Observing the mechanisms that function in human emotion expression, Paul
et al. suggest that concentration on similar mechanisms in animals can
provide clear insights into the animal experience. They noted that in
humans, cognitive biases
vary according to emotional state and suggested this as a possible
starting point to examine animal emotion. They propose that researchers
may be able to use controlled stimuli which have a particular meaning to
trained animals to induce particular emotions in these animals and
assess which types of basic emotions animals can experience.
Cognitive bias test
Is the glass half empty or half full?
A cognitive bias is a pattern of deviation in judgment, whereby
inferences about other animals and situations may be drawn in an
illogical fashion. Individuals create their own "subjective social reality" from their perception of the input. It refers to the question "Is the glass half empty or half full?",
used as an indicator of optimism or pessimism.
To test this in animals, an individual is trained to anticipate that
stimulus A, e.g. a 20 Hz tone, precedes a positive event, e.g. highly
desired food is delivered when a lever is pressed by the animal. The
same individual is trained to anticipate that stimulus B, e.g. a 10 Hz
tone, precedes a negative event, e.g. bland food is delivered when the
animal presses a lever. The animal is then tested by being played an
intermediate stimulus C, e.g. a 15 Hz tone, and observing whether the
animal presses the lever associated with the positive or negative
reward, thereby indicating whether the animal is in a positive or
negative mood. This might be influenced by, for example, the type of
housing the animal is kept in.
Using this approach, it has been found that rats which are
subjected to either handling or playful, experimenter-administered
manual stimulation (tickling) showed different responses to the intermediate stimulus: rats exposed to tickling were more optimistic.
The authors stated that they had demonstrated "...for the first time a
link between the directly measured positive affective state and decision
making under uncertainty in an animal model."
Cognitive biases have been shown in a wide range of species
including rats, dogs, rhesus macaques, sheep, chicks, starlings and
honeybees.
Self-medication with psychoactive drugs
Humans can suffer from a range of emotional or mood disorders such as depression, anxiety, fear and panic. To treat these disorders, scientists have developed a range of psychoactive drugs such as anxiolytics. Many of these drugs are developed and tested
by using a range of laboratory species. It is inconsistent to argue
that these drugs are effective in treating human emotions whilst denying
the experience of these emotions in the laboratory animals on which
they have been developed and tested.
Standard laboratory cages prevent mice from performing several
natural behaviours for which they are highly motivated. As a
consequence, laboratory mice sometimes develop abnormal behaviours
indicative of emotional disorders such as depression and anxiety. To
improve welfare, these cages are sometimes enriched with items such as
nesting material, shelters and running wheels. Sherwin and Ollson tested whether such enrichment influenced the consumption of Midazolam,
a drug widely used to treat anxiety in humans. Mice in standard cages,
standard cages but with unpredictable husbandry, or enriched cages,
were given a choice of drinking either non-drugged water or a solution
of the Midazolam. Mice in the standard and unpredictable cages drank a
greater proportion of the anxiolytic solution than mice from enriched
cages, indicating that mice from the standard and unpredictable
laboratory caging may have been experiencing greater anxiety than mice
from the enriched cages.
Whales have spindle cells in greater numbers and are maintained for twice as long as humans.
The exact function of spindle cells in whale brains is still not
understood, but Hof and Van Der Gucht believe that they act as some sort
of "high-speed connections that fast-track information to and from
other parts of the cortex".
They compared them to express trains that bypass unnecessary
connections, enabling organisms to instantly process and act on
emotional cues during complex social interactions. However, Hof and Van
Der Gucht clarify that they do not know the nature of such feelings in
these animals and that we cannot just apply what we see in great apes or
ourselves to whales. They believe that more work is needed to know
whether emotions are the same for humans and whales.
Vocalizations
Though
non-human animals cannot provide useful verbal feedback about the
experiential and cognitive details of their feelings, various emotional
vocalizations of other animals may be indicators of potential affective
states.
Beginning with Darwin and his research, it has been known that
chimpanzees and other great apes perform laugh-like vocalizations,
providing scientists with more symbolic self-reports of their emotional
experiences.
Research with rats has revealed that under particular conditions, they emit 50-kHz ultrasonic vocalisations (USV) which have been postulated to reflect a positive affective state (emotion) analogous to primitive human joy; these calls have been termed "laughter". The 50 kHz USVs in rats are uniquely elevated by hedonic stimuli—such as tickling, rewarding electrical brain stimulation, amphetamine injections, mating, play, and aggression—and are suppressed by aversive stimuli.[6] Of all manipulations that elicit 50 kHz chirps in rats, tickling by humans elicits the highest rate of these calls.
Some vocalizations of domestic cats, such as purring, are well
known to be produced in situations of positive valence, such as mother
kitten interactions, contacts with familiar partner, or during tactile
stimulation with inanimate objects as when rolling and rubbing.
Therefore, purring can be generally considered as an indicator of
"pleasure" in cats.
Low pitched bleating in sheep has been associated with some
positive-valence situations, as they are produced by males as an estrus
female is approaching or by lactating mothers while licking and nursing
their lambs.
Neurological
Neuroscientific
studies based off of the instinctual, emotional action tendencies of
non-human animals accompanied by the brains neurochemical and electrical
changes are deemed to best monitor relative primary process
emotional/affective states.
Predictions based off the research conducted on animals is what leads
analysis of the neural infrastructure relevant in humans.
Psycho-neuro-ethological triangulation with both humans and animals
allows for further experimentation into animal emotions. Utilizing
specific animals that exhibit indicators of emotional states to decode
underlying neural systems aids in the discovery of critical brain
variables that regulate animal emotional expressions. Comparing the
results of the animals converse experiments occur predicting the
affective changes that should result in humans.
Specific studies where there is an increase or decrease of playfulness
or separation distress vocalizations in animals, comparing humans that
exhibit the predicted increases or decreases in feelings of joy or
sadness, the weight of evidence constructs a concrete neural hypothesis
concerning the nature of affect supporting all relevant species.
Criticism
The
argument that animals experience emotions is sometimes rejected due to a
lack of evidence, and those who do not believe in the idea of animal
intelligence, often argue that anthropomorphism
plays a role in individuals' perspectives. Those who reject that
animals have the capacity to experience emotion do so mainly by
referring to inconsistencies in studies that have endorsed the belief
emotions exist. Having no linguistic means to communicate emotion beyond
behavioral response interpretation, the difficulty of providing an
account of emotion in animals relies heavily on interpretive
experimentation, that relies on results from human subjects.
Some people oppose the concept of animal emotions and suggest
that emotions are not universal, including in humans. If emotions are
not universal, this indicates that there is not a phylogenetic
relationship between human and non-human
emotion. The relationship drawn by proponents of animal emotion, then,
would be merely a suggestion of mechanistic features that promote
adaptivity, but lack the complexity of human emotional constructs. Thus,
a social life-style may play a role in the process of basic emotions
developing into more complex emotions.
Darwin concluded, through a survey, that humans share universal
emotive expressions and suggested that animals likely share in these to
some degree. Social constructionists disregard the concept that emotions
are universal. Others hold an intermediate stance, suggesting that
basic emotional expressions and emotion are universal but the
intricacies are developed culturally. A study by Elfenbein and Ambady
indicated that individuals within a particular culture are better at
recognising other cultural members' emotions.
Examples
Primates
Primates, in particular great apes, are candidates for being able to experience empathy and theory of mind. Great apes have complex social systems; young apes and their mothers have strong bonds of attachment and when a baby chimpanzee or gorilla dies, the mother will not uncommonly carry the body around for several days. Jane Goodall has described chimpanzees as exhibiting mournful behavior. Koko,
a gorilla trained to use sign language, was reported to have expressed
vocalizations indicating sadness after the death of her pet cat, All Ball.
Beyond such anecdotal evidence, support for empathetic reactions has come from experimental studies of rhesus macaques.
Macaques refused to pull a chain that delivered food to themselves if
doing so also caused a companion to receive an electric shock. This inhibition of hurting another conspecific was more pronounced between familiar than unfamiliar macaques, a finding similar to that of empathy in humans.
Furthermore, there has been research on consolation behavior in
chimpanzees. De Waal and Aureli found that third-party contacts attempt
to relieve the distress of contact participants by consoling (e.g.
making contact, embracing, grooming) recipients of aggression, especially those that have experienced more intense aggression. Researchers were unable to replicate these results using the same observation protocol in studies of monkeys, demonstrating a possible difference in empathy between monkeys and apes.
Other studies have examined emotional processing in the great apes.
Specifically, chimpanzees were shown video clips of emotionally charged
scenes, such as a detested veterinary procedure or a favorite food, and
then were required to match these scenes with one of two
species-specific facial expressions: "happy" (a play-face) or "sad" (a
teeth-baring expression seen in frustration or after defeat). The
chimpanzees correctly matched the clips to the facial expressions that
shared their meaning, demonstrating that they understand the emotional
significance of their facial expressions. Measures of peripheral skin
temperature also indicated that the video clips emotionally affected the
chimpanzees.
Rodents
In 1998, Jaak Panksepp proposed that all mammalian species are equipped with brains capable of generating emotional experiences. Subsequent work examined studies on rodents to provide foundational support for this claim. One of these studies examined whether rats would work to alleviate the distress of a conspecific.
Rats were trained to press a lever to avoid the delivery of an electric
shock, signaled by a visual cue, to a conspecific. They were then
tested in a situation in which either a conspecific or a Styrofoam block
was hoisted into the air and could be lowered by pressing a lever. Rats
that had previous experience with conspecific distress demonstrated
greater than ten-fold more responses to lower a distressed conspecific
compared to rats in the control group, while those who had never
experienced conspecific distress expressed greater than three-fold more
responses to lower a distressed conspecific relative to the control
group. This suggests that rats will actively work to reduce the distress
of a conspecific, a phenomenon related to empathy. Comparable results
have also been found in similar experiments designed for monkeys.
Langford et al. examined empathy in rodents using an approach based in neuroscience. They reported that (1) if two mice
experienced pain together, they expressed greater levels of
pain-related behavior than if pain was experienced individually, (2) if
experiencing different levels of pain together, the behavior of each
mouse was modulated by the level of pain experienced by its social
partner, and (3) sensitivity to a noxious stimulus was experienced to
the same degree by the mouse observing a conspecific in pain as it was
by the mouse directly experiencing the painful stimulus. The authors
suggest this responsiveness to the pain of others demonstrated by mice
is indicative of emotional contagion, a phenomenon associated with empathy, which has also been reported in pigs.
One behaviour associated with fear in rats is freezing. If female rats
experience electric shocks to the feet and then witness another rat
experiencing similar footshocks, they freeze more than females without
any experience of the shocks. This suggests empathy in experienced rats
witnessing another individual being shocked. Furthermore, the
demonstrator's behaviour was changed by the behaviour of the witness;
demonstrators froze more following footshocks if their witness froze
more creating an empathy loop.
Several studies have also shown rodents can respond to a conditioned stimulus that has been associated with the distress of a conspecific, as if it were paired with the direct experience of an unconditioned stimulus. These studies suggest that rodents are capable of shared affect, a concept critical to empathy.
Horses
Although
not direct evidence that horses experience emotions, a 2016 study showed
that domestic horses react differently to seeing photographs of
positive (happy) or negative (angry) human facial expressions. When
viewing angry faces, horses look more with their left eye which is
associated with perceiving negative stimuli. Their heart rate also
increases more quickly and they show more stress-related behaviours. One
rider wrote, 'Experienced riders and trainers can learn to read the
subtle moods of individual horses according to wisdom passed down from
one horseman to the next, but also from years of trial-and-error. I
suffered many bruised toes and nipped fingers before I could detect a
curious swivel of the ears, irritated flick of the tail, or concerned
crinkle above a long-lashed eye.' This suggests that horses have
emotions and display them physically but is not concrete evidence.
Birds
Marc Bekoff reported accounts of animal behaviour which he believed was evidence of animals being able to experience emotions in his book The Emotional Lives of Animals. The following is an excerpt from his book:
“
A few
years ago my friend Rod and I were riding our bicycles around Boulder,
Colorado, when we witnessed a very interesting encounter among five magpies.
Magpies are corvids, a very intelligent family of birds. One magpie had
obviously been hit by a car and was laying dead on the side of the
road. The four other magpies were standing around him. One approached
the corpse, gently pecked at it-just as an elephant noses the carcass of
another elephant- and stepped back. Another magpie did the same thing.
Next, one of the magpies flew off, brought back some grass, and laid it
by the corpse. Another magpie did the same. Then, all four magpies stood
vigil for a few seconds and one by one flew off.
”
Bystander
affiliation is believed to represent an expression of empathy in which
the bystander tries to console a conflict victim and alleviate their
distress. There is evidence for bystander affiliation in ravens (e.g.
contact sitting, preening, or beak-to-beak or beak-to-body touching) and
also for solicited bystander affiliation, in which there is
post-conflict affiliation from the victim to the bystander. This
indicates that ravens may be sensitive to the emotions of others,
however, relationship value plays an important role in the prevalence
and function of these post-conflict interactions.
The capacity of domestic hens to experience empathy
has been studied. Mother hens show one of the essential underpinning
attributes of empathy: the ability to be affected by, and share, the
emotional state of their distressed chicks. However, evidence for empathy between familiar adult hens has not yet been found.
Dogs
A drawing by Konrad Lorenz showing facial expressions of a dog
Some research indicates that domestic dogs may experience negative
emotions in a similar manner to humans, including the equivalent of
certain chronic and acute psychological conditions. Much of this is from
studies by Martin Seligman on the theory of learned helplessness as an extension of his interest in depression:
A dog that had earlier been
repeatedly conditioned to associate an audible stimulus with inescapable
electric shocks did not subsequently try to escape the electric shocks
after the warning was presented, even though all the dog would have had
to do is jump over a low divider within ten seconds. The dog didn't even
try to avoid the "aversive stimulus"; it had previously "learned" that
nothing it did would reduce the probability of it receiving a shock. A
follow-up experiment involved three dogs affixed in harnesses, including
one that received shocks of identical intensity and duration to the
others, but the lever which would otherwise have allowed the dog a
degree of control was left disconnected and didn't do anything. The
first two dogs quickly recovered from the experience, but the third dog
suffered chronic symptoms of clinical depression as a result of this perceived helplessness.
A further series of experiments showed that, similar to humans, under
conditions of long-term intense psychological stress, around one third
of dogs do not develop learned helplessness or long-term depression.
Instead these animals somehow managed to find a way to handle the
unpleasant situation in spite of their past experience. The
corresponding characteristic in humans has been found to correlate
highly with an explanatory style and optimisticattitude that views the situation as other than personal, pervasive, or permanent.
Since these studies, symptoms analogous to clinical depression, neurosis, and other psychological conditions have also been accepted as being within the scope of emotion in domestic dogs. The postures of dogs may indicate their emotional state. In some instances, the recognition of specific postures and behaviors can be learned.
Psychology research has shown that when humans gaze at the face
of another human, the gaze is not symmetrical; the gaze instinctively
moves to the right side of the face to obtain information about their
emotions and state. Research at the University of Lincoln
shows that dogs share this instinct when meeting a human, and only when
meeting a human (i.e. not other animals or other dogs). They are the
only non-primate species known to share this instinct.
The existence and nature of personality traits in dogs have been
studied (15,329 dogs of 164 different breeds). Five consistent and
stable "narrow traits" were identified, described as playfulness,
curiosity/fearlessness, chase-proneness, sociability and aggressiveness.
A further higher order axis for shyness–boldness was also identified.
Dogs presented with images of either human or dog faces with
different emotional states (happy/playful or angry/aggressive) paired
with a single vocalization (voices or barks) from the same individual
with either a positive or negative emotional state or brown noise.
Dogs look longer at the face whose expression is congruent to the
emotional state of the vocalization, for both other dogs and humans.
This is an ability previously known only in humans.
The behavior of a dog can not always be an indication of its
friendliness. This is because when a dog wags its tail, most people
interpret this as the dog expressing happiness and friendliness. Though
indeed tail wagging can express these positive emotions, tail wagging is
also an indication of fear, insecurity, challenging of dominance,
establishing social relationships or a warning that the dog may bite.
Some researchers are beginning to investigate the question of whether dogs have emotions with the help of magnetic resonance imaging.
Elephants
Elephants
are known for their empathy towards members of the same species as well
as their cognitive memory. While this is true scientists continuously
debate the extent to which elephants feel emotion.
Observations show that elephants, like humans, are concerned with
distressed or deceased individuals, and render assistance to the ailing
and show a special interest in dead bodies of their own kind, however
this view is interpreted as being anthropomorphic.
Elephants have recently been suggested to pass mirror
self-recognition tests, and such tests have been linked to the capacity
for empathy. However, the experiment showing such actions did not follow
the accepted protocol for tests of self-recognition, and earlier
attempts to show mirror self-recognition in elephants have failed, so
this remains a contentious claim.
Elephants are also deemed to show emotion through vocal
expression, specifically the rumble vocalization. Rumbles are frequency
modulated, harmonically rich calls with fundamental frequencies in the
infrasonic range, with clear formant structure. Elephants exhibit
negative emotion and/or increased emotional intensity through their
rumbles, based on specific periods of social interaction and agitation.
Cats
Cat's response to a fear inducing stimulus.
It has been postulated that domestic cats can learn to manipulate their owners through vocalizations that are similar to the cries of human babies. Some cats learn to add a purr to the vocalization, which makes it less harmonious and more dissonant to humans, and therefore harder to ignore. Individual cats learn to make these vocalizations through trial-and-error;
when a particular vocalization elicits a positive response from a
human, the probability increases that the cat will use that vocalization
in the future.
Growling can be an expression of annoyance or fear, similar to
humans. When annoyed or angry, a cat wriggles and thumps its tail much
more vigorously than when in a contented state. In larger felids such
as lions,
what appears to be irritating to them varies between individuals. A
male lion may let his cubs play with his mane or tail, or he may hiss
and hit them with his paws.
Domestic male cats also have variable attitudes towards their family
members, for example, older male siblings tend not to go near younger or
new siblings and may even show hostility toward them.
Hissing
is also a vocalization associated with either offensive or defensive
aggression. They are usually accompanied by a postural display intended
to have a visual effect on the perceived threat. Cats hiss when they are
startled, scared, angry, or in pain, and also to scare off intruders
into their territory. If the hiss and growl warning does not remove the
threat, an attack by the cat may follow. Kittens as young as two to
three weeks will potentially hiss when first picked up by a human.
Honeybees
Honeybees become pessimistic after being shaken
Honeybees ("Apis mellifera carnica") were trained to extend their proboscis to a two-component odour mixture (CS+) predicting a reward (e.g., 1.00 or 2.00 M sucrose)
and to withhold their proboscis from another mixture (CS−) predicting
either punishment or a less valuable reward (e.g., 0.01 M quinine
solution or 0.3 M sucrose). Immediately after training, half of the
honeybees were subjected to vigorous shaking for 60 s to simulate the
state produced by a predatory attack on a concealed colony. This shaking
reduced levels of octopamine, dopamine, and serotonin in the hemolymph
of a separate group of honeybees at a time point corresponding to when
the cognitive bias tests were performed. In honeybees, octopamine is the
local neurotransmitter
that functions during reward learning, whereas dopamine mediates the
ability to learn to associate odours with quinine punishment. If flies
are fed serotonin, they are more aggressive; flies depleted of serotonin
still exhibit aggression, but they do so much less frequently.
Within 5 minutes of the shaking, all the trained bees began a
sequence of unreinforced test trials with five odour stimuli presented
in a random order for each bee: the CS+, the CS−, and three novel odours
composed of ratios intermediate between the two learned mixtures.
Shaken honeybees were more likely to withhold their mouthparts from the
CS− and from the most similar novel odour. Therefore, agitated honeybees
display an increased expectation of bad outcomes similar to a
vertebrate-like emotional state. The researchers of the study stated
that, "Although our results do not allow us to make any claims about the
presence of negative subjective feelings in honeybees, they call into
question how we identify emotions in any non-human animal. It is
logically inconsistent to claim that the presence of pessimistic
cognitive biases should be taken as confirmation that dogs or rats are
anxious but to deny the same conclusion in the case of honeybees."
Crayfish naturally explore new environments but display a general preference for dark places. A 2014 study on the freshwater crayfish Procambarus clarkii tested their responses in a fear paradigm, the elevated plus maze
in which animals choose to walk on an elevated cross which offers both
aversive and preferable conditions (in this case, two arms were lit and
two were dark). Crayfish which experienced an electric shock displayed
enhanced fearfulness or anxiety as demonstrated by their preference for
the dark arms more than the light. Furthermore, shocked crayfish had
relatively higher brain serotonin concentrations coupled with elevated blood glucose, which indicates a stress response. Moreover, the crayfish calmed down when they were injected with the benzodiazepine anxiolytic, chlordiazepoxide,
used to treat anxiety in humans, and they entered the dark as normal.
The authors of the study concluded "...stress-induced avoidance behavior
in crayfish exhibits striking homologies with vertebrate anxiety."
A follow-up study using the same species confirmed the anxiolytic
effect of chlordiazepoxide, but moreover, the intensity of the
anxiety-like behaviour was dependent on the intensity of the electric
shock until reaching a plateau. Such a quantitative relationship between
stress and anxiety is also a very common feature of human and
vertebrate anxiety.