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122-411: During the early twentieth century, the public was especially interested in animal intelligence owing in large part to Charles Darwin 's recent publications. The case of Clever Hans was taken to show an advanced level of number sense in an animal . Hans was a horse owned by Wilhelm von Osten, who was a gymnasium mathematics teacher, an amateur horse trainer and phrenologist and was considered to be

244-490: A Piagetian methodology, taking tasks which human children are known to master at different stages of development and investigating which of them can be performed by particular species. Others have been inspired by concerns for animal welfare and the management of domestic species; for example, Temple Grandin has harnessed her unique expertise in animal welfare and the ethical treatment of farm livestock to highlight underlying similarities between humans and other animals. From

366-695: A mystic . Hans was said to have been taught to add, subtract, multiply, divide, work with fractions, tell the time, keep track of the calendar, differentiate between musical tones, and read, spell, and understand German. Von Osten would ask Hans, "If the eighth day of the month comes on a Tuesday, what is the date of the following Friday?" Hans would answer by tapping his hoof eleven times. Questions could be asked both orally and in written form. Von Osten exhibited Hans throughout Germany and never charged admission. Hans' abilities were reported in The New York Times in 1904. After von Osten died in 1909, Hans

488-626: A Clever Hans effect was present in a two-way object choice test and included an experimental group in which the owners actively tried to influence their dog's decision. The results showed that the experimenter had the strongest effect on the dog's choice in this task, regardless of the owner's knowledge or actions. This provides evidence that the Clever Hans effect is not always present when humans and dogs interact. Pfungst's final experiment showed that Clever Hans effects can occur in experiments with humans as well as with animals. For this reason, care

610-616: A behavior)? Theories addressing the proximate causes of behavior are based on answers to these two questions. For more details see Tinbergen's four questions . The 9th century scholar al-Jahiz wrote works on the social organization and communication methods of animals like ants. The 11th century Arabic writer Ibn al-Haytham (Alhazen) wrote the Treatise on the Influence of Melodies on the Souls of Animals , an early treatise dealing with

732-468: A black square, the correct choice is "green". Ingenious variations of this method have been used to explore many aspects of memory, including forgetting due to interference and memory for multiple items. The radial arm maze is used to test memory for spatial location and to determine the mental processes by which location is determined. In a radial maze test, an animal is placed on a small platform from which paths lead in various directions to goal boxes;

854-560: A broader meaning, comparative psychology includes comparisons between different biological and socio-cultural groups, such as species , sexes , developmental stages, ages, and ethnicities . Research in this area addresses many different issues, uses many different methods and explores the behavior of many different species, from insects to primates . Comparative psychology is sometimes assumed to emphasize cross-species comparisons, including those between humans and animals. However, some researchers feel that direct comparisons should not be

976-433: A class if they have a common use or lead to common consequences. An oft-cited study by Vaughan (1988) provides an example. Vaughan divided a large set of unrelated pictures into two arbitrary sets, A and B. Pigeons got food for pecking at pictures in set A but not for pecks at pictures in set B. After they had learned this task fairly well, the outcome was reversed: items in set B led to food and items in set A did not. Then

1098-490: A cross-fostered chimpanzee named Gua was better at recognizing human smells and clothing and that the Kelloggs' infant (Donald) recognised humans better by their faces. The study ended nine months after it had begun, after the infant began to imitate the noises of Gua. Nonhuman primates have also been used to show the development of language in comparison with human development. For example, Gardner (1967) successfully taught

1220-528: A crow drops pebbles into a vessel of water until he is able to drink. This was a relatively accurate reflection of the capability of corvids to understand water displacement. The Roman naturalist Pliny the Elder was the earliest to attest that said story reflects the behavior of real-life corvids. Aristotle , in his biology , hypothesized a causal chain where an animal's sense organs transmitted information to an organ capable of making decisions, and then to

1342-477: A flood of informative books and television programs on ethological studies that came to be widely seen and read in the United States. At present, comparative psychology in the United States is moribund. Throughout the long history of comparative psychology, repeated attempts have been made to enforce a more disciplined approach, in which similar studies are carried out on animals of different species, and

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1464-537: A fundamental precept of comparative (animal) psychology . In its developed form, it states that: 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. In other words, Morgan believed that anthropomorphic approaches to animal behavior were fallacious, and that people should only consider behaviour as, for example, rational, purposive or affectionate, if there

1586-428: A great deal of practice with many different stimuli. However, because the sample is presented first, successful matching might mean that the animal is simply choosing the most recently seen "familiar" item rather than the conceptually "same" item. A number of studies have attempted to distinguish these possibilities, with mixed results. The use of rules has sometimes been considered an ability restricted to humans, but

1708-457: A hard-and-fast line between their own nature and that of all other animals. Children have no scruples over allowing animals to rank as their full equals." With maturity however, humans find it hard to accept that they themselves are animals, so they categorize, separating humans from animals, and animals into wild animals and tame animals, and tame animals into house pets and livestock. Such divisions can be seen as similar to categories of humans: who

1830-469: A key role in the defense of Darwinism and its refinement over the years. Still, Romanes is most famous for two major flaws in his work: his focus on anecdotal observations and entrenched anthropomorphism . Unsatisfied with the previous approach, E. L. Thorndike brought animal behavior into the laboratory for objective scrutiny. Thorndike's careful observations of the escape of cats, dogs, and chicks from puzzle boxes led him to conclude that what appears to

1952-434: A large effect on experimental design and methodology for all experiments whatsoever involving sentient subjects, including humans. The risk of Clever Hans effects is one reason why comparative psychologists normally test animals in isolated apparatus, without interaction with them. However this creates problems of its own, because many of the most interesting phenomena in animal cognition are only likely to be demonstrated in

2074-429: A level of empathy in dogs, a point that is strongly debated. Pilley and Reid found that a Border Collie named Chaser was able to successfully identify and retrieve 1022 distinct objects/toys. Researchers who study animal cognition are interested in understanding the mental processes that control complex behavior, and much of their work parallels that of cognitive psychologists working with humans. For example, there

2196-437: A lever brings food" or "children give me peanuts". This is one of the simplest tests for memory spanning a short time interval. The test compares an animal's response to a stimulus or event on one occasion to its response on a previous occasion. If the second response differs consistently from the first, the animal must have remembered something about the first, unless some other factor such as motivation, sensory sensitivity, or

2318-421: A light appeared briefly in one of three goal boxes and then later the animal chose among the boxes, finding food behind the one that had been lighted. Most research has been done with some variation of the "delayed matching-to-sample" task. For example, in the initial study with this task, a pigeon was presented with a flickering or steady light. Then, a few seconds later, two pecking keys were illuminated, one with

2440-624: A little later of the outspoken behaviorist John B. Watson set the direction of much research on animal behavior for more than half a century. During this time there was considerable progress in understanding simple associations; notably, around 1930 the differences between Thorndike's instrumental (or operant) conditioning and Pavlov's classical (or Pavlovian) conditioning were clarified, first by Miller and Kanorski, and then by B. F. Skinner . Many experiments on conditioning followed; they generated some complex theories, but they made little or no reference to intervening mental processes. Probably

2562-622: A long period will ultimately develop unwanted behaviors that have been compared with human psychosis , like biting their owners. The way dogs behave when understimulated is widely believed to depend on the breed as well as on the individual animal's character. For example, huskies have been known to ruin gardens and houses if they are not allowed enough activity. Dogs are also prone to psychological damage if they are subjected to violence. If they are treated very badly, they may become dangerous. The systematic study of disordered animal behavior draws on research in comparative psychology, including

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2684-425: A methodological point of view, one of the main risks in this sort of work is anthropomorphism , the tendency to interpret an animal's behavior in terms of human feelings , thoughts, and motivations. Human and non-human animal cognition have much in common, and this is reflected in the research summarized below; most of the headings found here might also appear in an article on human cognition. Of course, research in

2806-466: A moth of species A, a moth of species B, or no moth at all. The birds were rewarded for pecks at a picture showing a moth. Crucially, the probability with which a particular species of moth was detected was higher after repeated trials with that species (e.g. A, A, A,...) than it was after a mixture of trials (e.g. A, B, B, A, B, A, A...). These results suggest again that sequential encounters with an object can establish an attentional predisposition to see

2928-548: A motor organ. Despite Aristotle's cardiocentrism (mistaken belief that cognition occurred in the heart), this approached some modern understandings of information processing . Early inferences were not necessarily precise or accurate. Nonetheless, interest in animal mental abilities, and comparisons to humans, increased with early myrmecology , the study of ant behavior, as well as the classification of humans as primates beginning with Linnaeus . Coined by 19th-century British psychologist C. Lloyd Morgan , Morgan's Canon remains

3050-650: A number of experiments have shown evidence of simple rule learning in primates and also in other animals. Much of the evidence has come from studies of sequence learning in which the "rule" consists of the order in which a series of events occurs. Rule use is shown if the animal learns to discriminate different orders of events and transfers this discrimination to new events arranged in the same order. For example, Murphy et al. (2008) trained rats to discriminate between visual sequences. For one group ABA and BAB were rewarded, where A="bright light" and B="dim light". Other stimulus triplets were not rewarded. The rats learned

3172-406: A number of species. One of the most common methods is the "peak procedure". In a typical experiment, a rat in an operant chamber presses a lever for food. A light comes on, a lever-press brings a food pellet at a fixed later time, say 10 seconds, and then the light goes off. Timing is measured during occasional test trials on which no food is presented and the light stays on. On these test trials,

3294-659: A panel of 13 people, known as the Hans Commission . This commission consisted of a veterinarian, a circus manager, a cavalry officer, a number of schoolteachers, and the director of the Berlin zoological gardens. This commission concluded in September 1904 that no tricks were involved in Hans's performance. The commission passed off the evaluation to Oskar Pfungst , who tested the basis for these claimed abilities by: Using

3416-405: A person is currently thinking about. Animal intelligence Animal cognition encompasses the mental capacities of non-human animals , including insect cognition . The study of animal conditioning and learning used in this field was developed from comparative psychology . It has also been strongly influenced by research in ethology , behavioral ecology , and evolutionary psychology ;

3538-716: A person or animal responds in a similar way to a range of stimuli that share common features. For example, a squirrel climbs a tree when it sees Rex, Shep, or Trixie, which suggests that it categorizes all three as something to avoid. This sorting of instances into groups is crucial to survival. Among other things, an animal must categorize if it is to apply learning about one object (e.g. Rex bit me) to new instances of that category (dogs may bite). Many animals readily classify objects by perceived differences in form or color. For example, bees or pigeons quickly learn to choose any red object and reject any green object if red leads to reward and green does not. Seemingly much more difficult

3660-470: A second stimulus ("B") accompanies A on additional training trials. Later tests with the B stimulus alone elicit little response, suggesting that learning about B has been blocked by prior learning about A. This result supports the hypothesis that stimuli are neglected if they fail to provide new information. Thus, in the experiment just cited, the animal failed to attend to B because B added no information to that supplied by A. If true, this interpretation

3782-419: A short-term memory of approximately 1 min and long-term memory of 1 month. As in humans, research with animals distinguishes between "working" or "short-term" memory from "reference" or long-term memory. Tests of working memory evaluate memory for events that happened in the recent past, usually within the last few seconds or minutes. Tests of reference memory evaluate memory for regularities such as "pressing

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3904-521: A simple stimulus matching-to-sample task (described above) many animals readily learn specific item combinations, such as "touch red if the sample is red, touch green if the sample is green." But this does not demonstrate that they distinguish between "same" and "different" as general concepts. Better evidence is provided if, after training, an animal successfully makes a choice that matches a novel sample that it has never seen before. Monkeys and chimpanzees do learn to do this, as do pigeons if they are given

4026-410: A small number have dominated the scene. Ivan Pavlov 's early work used dogs; although they have been the subject of occasional studies, since then they have not figured prominently. Increasing interest in the study of abnormal animal behavior has led to a return to the study of most kinds of domestic animal. Thorndike began his studies with cats, but American comparative psychologists quickly shifted to

4148-405: A social context, and in order to train and demonstrate them, it is necessary to build up a social relationship between trainer and animal. This point of view has been strongly argued by Irene Pepperberg in relation to her studies of parrots ( Alex ), and by Allen and Beatrix Gardner in their study of the chimpanzee Washoe . If the results of such studies are to gain universal acceptance, it

4270-399: A steady light and one with a flickering light. The bird got food if it pecked the key that matched the original stimulus. A commonly-used variation of the matching-to-sample task requires the animal to use the initial stimulus to control a later choice between different stimuli. For example, if the initial stimulus is a black circle, the animal learns to choose "red" after the delay; if it is

4392-406: A substantial number of trials, Pfungst found that the horse could get the correct answer even if von Osten himself did not ask the questions, ruling out the possibility of fraud. However, the horse gave the right answer only when the questioner knew what the answer was and the horse could see the questioner. He observed that when Hans could see the questioner, the horse got 89 percent (50 out of 56) of

4514-402: A task can be performed rather simply, for example by following a chemical trail. Typically, however, the animal must somehow acquire and use information about locations, directions, and distances. The following paragraphs outline some of the ways that animals do this. Many animals travel hundreds or thousands of miles in seasonal migrations or returns to breeding grounds. They may be guided by

4636-415: A tone and a light are presented simultaneously to pigeons. The pigeons gain a reward only by choosing the correct combination of the two stimuli (e.g. a high frequency tone together with a yellow light). The birds perform well at this task, presumably by dividing attention between the two stimuli. When only one of the stimuli varies and the other is presented at its rewarded value, discrimination improves on

4758-445: A typical experiment, a bird or other animal confronts a computer monitor on which a large number of pictures appear one by one, and the subject gets a reward for pecking or touching a picture of a category item and no reward for non-category items. Alternatively, a subject may be offered a choice between two or more pictures. Many experiments end with the presentation of items never seen before; successful sorting of these items shows that

4880-408: Is a circular tank filled with water that has been made milky so that it is opaque. Located somewhere in the maze is a small platform placed just below the surface of the water. When placed in the tank, the animal swims around until it finds and climbs up on the platform. With practice, the animal finds the platform more and more quickly. Reference memory is assessed by removing the platform and observing

5002-647: Is a well known case study (1976–2007) which was developed by Pepperberg, who found that the African gray parrot Alex did not only mimic vocalisations but understood the concepts of same and different between objects. The study of non-human mammals has also included the study of dogs. Due to their domestic nature and personalities, dogs have lived closely with humans, and parallels in communication and cognitive behaviours have therefore been recognised and further researched. Joly-Mascheroni and colleagues (2008) demonstrated that dogs may be able to catch human yawns and suggested

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5124-425: Is an animal's ability to categorize natural objects that vary a great deal in color and form even while belonging to the same group. In a classic study, Richard J. Herrnstein trained pigeons to respond to the presence or absence of human beings in photographs. The birds readily learned to peck photos that contained partial or full views of humans and to avoid pecking photos with no human, despite great differences in

5246-451: Is an important insight into attentional processing, but this conclusion remains uncertain because blocking and several related phenomena can be explained by models of conditioning that do not invoke attention. Attention is a limited resource and is not a none-or-all response: the more attention devoted to one aspect of the environment, the less is available for others. A number of experiments have studied this in animals. In one experiment,

5368-404: Is based on a rodents innate exploratory behavior. The test is divided into three phases: habituation, training/adaptation and test phase. During the habituation phase the animal is placed in an empty test arena. This is followed by the adaptation phase, where the animal is placed in the arena with two identical objects. In the third phase, the test phase, the animal is placed in the arena with one of

5490-418: Is being communicated. All great apes have been reported to have the capacity of allospecific symbolic production. Interest in primate studies has increased with the rise in studies of animal cognition. Other animals thought to be intelligent have also been increasingly studied. Examples include various species of corvid , parrots—especially the grey parrot —and dolphins . Alex (Avian Learning Experiment)

5612-543: Is closest to human performance and neglects behaviors that humans are usually incapable of (e.g. echolocation ). Specifically, comparative researchers encounter problems associated with individual differences, differences in motivation, differences in reinforcement, differences in sensory function, differences in motor capacities, and species-typical preparedness (i.e. some species have evolved to acquire some behaviors quicker than other behaviors). A wide variety of species have been studied by comparative psychologists. However,

5734-453: Is extensive research with animals on attention, categorization, concept formation, memory, spatial cognition, and time estimation. Much research in these and other areas is related directly or indirectly to behaviors important to survival in natural settings, such as navigation, tool use, and numerical competence. Thus, comparative psychology and animal cognition are heavily overlapping research categories. Veterinary surgeons recognize that

5856-407: Is freely available online. Most work on animal concepts has been done with visual stimuli, which can easily be constructed and presented in great variety, but auditory and other stimuli have been used as well. Pigeons have been widely used, for they have excellent vision and are readily conditioned to respond to visual targets; other birds and a number of other animals have been studied as well. In

5978-428: Is happening in the world at any moment is irrelevant to current behavior. Attention refers to mental processes that select relevant information, inhibit irrelevant information, and switch among these as the situation demands. Often the selective process is tuned before relevant information appears; such expectation makes for rapid selection of key stimuli when they become available. A large body of research has explored

6100-466: Is necessary to find some way of testing the animals' achievements which eliminates the risk of Clever Hans effects. However, simply removing the trainer from the scene may not be an appropriate strategy, because where the social relationship between trainer and subject is strong, the removal of the trainer may produce emotional responses preventing the subject from performing. It is therefore necessary to devise procedures where none of those present knows what

6222-450: Is no other explanation in terms of the behaviours of more primitive life-forms to which we do not attribute those faculties. Speculation about animal intelligence gradually yielded to scientific study after Darwin placed humans and animals on a continuum, although Darwin's largely anecdotal approach to the cognition topic would not pass scientific muster later on. This method would be expanded by his protégé George J. Romanes , who played

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6344-598: Is non-feeder specific and a feeder specific long-term reference memory. Memory induced in a free-flying honeybee by a single learning trial lasts for days and, by three learning trials, for a lifetime. Bombus terrestris audax workers vary in their effort investment towards memorising flower locations, with smaller workers less able to be selective and thus less interested in which flowers are richer sugar sources. Meanwhile, bigger B. t. audax workers have more carrying capacity and thus more reason to memorise that information, and so they do. Slugs, Limax flavus , have

6466-470: Is often taken in fields such as perception , cognitive psychology , and social psychology to make experiments double-blind , meaning that neither the experimenter nor the subject knows what condition the subject is in, and thus what their responses are predicted to be. Another way in which Clever Hans effects are avoided is by replacing the experimenter with a computer, which can deliver standardized instructions and record responses without giving clues. In

6588-428: Is part of a human community and someone who is not—that is, the outsider. The New York Times ran an article that showed the psychological benefits of animals, more specifically of children with their pets. It has been proven that having a pet does in fact improve kids' social skills. In the article, Dr. Sue Doescher, a psychologist involved in the study, stated, "It made the children more cooperative and sharing." It

6710-404: Is synchronized with the earth's daily light-dark cycle. Thus, many animals are active during the day, others are active at night, still others near dawn and dusk. Though one might think that these "circadian rhythms" are controlled simply by the presence or absence of light, nearly every animal that has been studied has been shown to have a "biological clock" that yields cycles of activity even when

6832-404: The behavior and mental processes of non- human animals , especially as these relate to the phylogenetic history, adaptive significance, and development of behavior. The phrase comparative psychology may be employed in either a narrow or a broad meaning. In its narrow meaning, it refers to the study of the similarities and differences in the psychology and behavior of different species. In

6954-715: The concept of "concept" was discussed for hundreds of years by philosophers before it became a focus of psychological study. Concepts enable humans and animals to organize the world into functional groups; the groups may be composed of perceptually similar objects or events, diverse things that have a common function, relationships such as same versus different, or relations among relations such as analogies. Extensive discussions on these matters together with many references may be found in Shettleworth (2010) Wasserman and Zentall (2006) and in Zentall et al. (2008). The latter

7076-523: The Sun, the stars, the polarization of light, magnetic cues, olfactory cues, winds, or a combination of these. It has been hypothesized that animals such as apes and wolves are good at spatial cognition because this skill is necessary for survival. Some researchers argue that this ability may have diminished somewhat in dogs because humans have provided necessities such as food and shelter during some 15,000 years of domestication. The behavior of most animals

7198-613: The alternative name cognitive ethology is sometimes used. Many behaviors associated with the term animal intelligence are also subsumed within animal cognition. Researchers have examined animal cognition in mammals (especially primates , cetaceans , elephants , bears , dogs , cats , pigs , horses , cattle , raccoons and rodents ), birds (including parrots , fowl , corvids and pigeons ), reptiles ( lizards , snakes , and turtles ), fish and invertebrates (including cephalopods , spiders and insects ). The mind and behavior of non-human animals has captivated

7320-427: The animal finds food in one or more goal boxes. Having found food in a box, the animal must return to the central platform. The maze may be used to test both reference and working memory. Suppose, for example, that over a number of sessions the same 4 arms of an 8-arm maze always lead to food. If in a later test session the animal goes to a box that has never been baited, this indicates a failure of reference memory. On

7442-415: The animal has not simply learned many specific stimulus-response associations. A related method, sometimes used to study relational concepts, is matching-to-sample. In this task an animal sees one stimulus and then chooses between two or more alternatives, one of which is the same as the first; the animal is then rewarded for choosing the matching stimulus. Perceptual categorization is said to occur when

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7564-428: The animal is in constant illumination or darkness. Circadian rhythms are so automatic and fundamental to living things – they occur even in plants – that they are usually discussed separately from cognitive processes, and the reader is referred to the main article ( Circadian rhythms ) for further information. Survival often depends on an animal's ability to time intervals. For example, rufous hummingbirds feed on

7686-402: The animal to choose from several alternatives. For example, several studies have shown that performance is better on, for example, a color discrimination (e.g. blue vs green) after the animal has learned another color discrimination (e.g. red vs orange) than it is after training on a different dimension such as an X shape versus an O shape. The reverse effect happens after training on forms. Thus,

7808-412: The animal's likely response may be. The Clever Hans effect has also been observed in drug-sniffing dogs . A study at University of California, Davis revealed that cues can be telegraphed by the handler to the dogs, resulting in false positives. A 2004 study of Rico , a border collie reported by his owners as having a vocabulary of over 200 words, avoided the Clever Hans effect by having the owner ask

7930-401: The answers correct, but when Hans was not able to see the questioner, the horse answered only six percent (2 out of 35) of the questions correctly. Pfungst was aware of the ability of circus trainers to train horses to respond to small gestures, and was aware of a number of cases of dogs, like that of English astrophysicist Sir William Huggins , who were able to point to an object their master

8052-455: The behavior of animals in their natural environments and discuss the putative function of the behavior for the propagation and survival of the species. These developments reflect an increased cross-fertilization from related fields such as ethology and behavioral ecology . Contributions from behavioral neuroscience are beginning to clarify the physiological substrate of some inferred mental process. Some researchers have made effective use of

8174-835: The behavior of humans and animals have sometimes been used in an attempt to understand the evolutionary significance of particular behaviors. Differences in the treatment of animals have been said to reflect a society's understanding of human nature and the place of humans and animals in the scheme of things. Domestication has been of particular interest. For example, it has been argued that, as animals became domesticated, humans treated them as property and began to see them as inferior or fundamentally different from humans. Ingold remarks that in all societies children have to learn to differentiate and separate themselves from others. In this process, strangers may be seen as "not people", and like animals. Ingold quoted Sigmund Freud: "Children show no trace of arrogance which urges adult civilized men to draw

8296-495: The behavior)? Theories addressing the ultimate causes of behavior are based on the answers to these two questions. Third, what mechanisms are involved in the behavior (i.e. what physiological, behavioral, and environmental components are necessary and sufficient for the generation of the behavior)? Fourth, a researcher may ask about the development of the behavior within an individual (i.e. what maturational, learning, social experiences must an individual undergo in order to demonstrate

8418-452: The characteristics of attentional selection and the factors that control it. Experimental research on visual search in animals was initially prompted by field observations published by Luc Tinbergen (1960). Tinbergen observed that birds are selective when foraging for insects. For example, he found that birds tended to catch the same type of insect repeatedly even though several types were available. Tinbergen suggested that this prey selection

8540-493: The decision making of AI models in order to detect such Clever Hans correlations. The German conceptual artist Max Haarich demonstrated the Clever Hans effect in Artificial Intelligence with his art installation “Smart Hans”. Based on the information from Oskar Pfungst's book "Clever Hans" (1911), the installation shows an animated horse and uses facial detection and pose estimation to predict which number

8662-407: The demands of different tasks, or in their choice of species to compare. However, the definition of "intelligence" in comparative psychology is deeply affected by anthropomorphism; experiments focused on simple tasks, complex problems, reversal learning, learning sets, and delayed alternation were plagued with practical and theoretical problems. In the literature, "intelligence" is defined as whatever

8784-400: The dog to fetch items from an adjacent room, so that the owner could not provide real time feedback while the dog was selecting an object. A study conducted in 2012 examined the socio-communicative ability of dogs with humans, looking at how much of an influence an owner, if present, would have on their dog during an object-choice pointing task, including looking at whether a Clever Hans effect

8906-437: The earlier learning appears to affect which dimension, color or form, the animal will attend to. Other experiments have shown that after animals have learned to respond to one aspect of the environment responsiveness to other aspects is suppressed. In "blocking", for example, an animal is conditioned to respond to one stimulus ("A") by pairing that stimulus with reward or punishment. After the animal responds consistently to A,

9028-448: The early work on conditioning and instrumental learning, but also on ethological studies of natural behavior. However, at least in the case of familiar domestic animals, it also draws on the accumulated experience of those who have worked closely with the animals. The relationship between humans and animals has long been of interest to anthropologists as one pathway to an understanding the evolution of human behavior. Similarities between

9150-584: The effects of music on animals . In the treatise, he demonstrates how a camel's pace could be hastened or slowed with the use of music , and shows other examples of how music can affect animal behavior , experimenting with horses, birds and reptiles. Through to the 19th century, a majority of scholars in the Western world continued to believe that music was a distinctly human phenomenon, but experiments since then have vindicated Ibn al-Haytham's view that music does indeed have an effect on animals. Charles Darwin

9272-447: The environment. Perceptual processes have been studied in many species, with results that are often similar to those in humans. Equally interesting are those perceptual processes that differ from, or go beyond those found in humans, such as echolocation in bats and dolphins, motion detection by skin receptors in fish, and extraordinary visual acuity, motion sensitivity and ability to see ultraviolet light in some birds . Much of what

9394-435: The familiar objects from the previous phase and with one novel object. Based on the rodents innate curiosity, the animals that remember the familiar object will spend more time on investigating the novel object. Whether an animal ranges over a territory measured in square kilometers or square meters, its survival typically depends on its ability to do such things as find a food source and then return to its nest. Sometimes such

9516-565: The female chimpanzee Washoe 350 words in American Sign Language . Washoe subsequently passed on some of this teaching to her adopted offspring, Loulis . A criticism of Washoe's acquisition of sign language focused on the extent to which she actually understood what she was signing. Her signs may have just been based on an association to get a reward, such as food or a toy. Other studies concluded that apes do not understand linguistic input, but may form an intended meaning of what

9638-427: The field of Artificial Intelligence , the Clever Hans effect describes a phenomenon where an algorithm seems to make correct predictions without having the relevant data and/or by using incorrect reasoning. This effect can appear, when a Deep Neural Network 's predictions are dominated by unknown features, which were not intended for the task, e.g. when an Image Classifier "reads" text on a photo instead of analysing

9760-498: The form, size, and color of both the humans displayed and in the non-human pictures. In follow-up studies, pigeons categorized other natural objects (e.g. trees) and after training they were able without reward to sort photos they had not seen before . Similar work has been done with natural auditory categories, for example, bird songs. Honeybees ( Apis mellifera ) are able to form concepts of "up" and "down". Perceptually unrelated stimuli may come to be responded to as members of

9882-466: The human imagination for centuries. Many writers, such as Descartes , have speculated about the presence or absence of the animal mind. These speculations led to many observations of animal behavior before modern science and testing were available. This ultimately resulted in the creation of multiple hypotheses about animal intelligence. One of Aesop's Fables was The Crow and the Pitcher , in which

10004-512: The image motif. The Clever Hans effect can also be seen as a "secret" overfitting of Deep Neural Networks towards an unknown feature. This overfitting might not affect the algorithm at all as long as the unknown feature is present, while it could lead to unpredictable fails in the absence of the unknown feature. The existence of this effect and its practical imperceceptibility restrict the robustness and validity of most AI models . Explainable AI research tries to find methods to fully comprehend

10126-485: The label of the field is never likely to disappear completely. A persistent question with which comparative psychologists have been faced is the relative intelligence of different species of animal. Indeed, some early attempts at a genuinely comparative psychology involved evaluating how well animals of different species could learn different tasks. These attempts floundered; in retrospect it can be seen that they were not sufficiently sophisticated, either in their analysis of

10248-803: The last 50 years or so has led to a rapid expansion in the variety of species studied and methods employed. The remarkable behavior of large-brained animals such as primates and cetacea have claimed special attention, but all sorts of animals large and small (birds, fish, ants, bees, and others) have been brought into the laboratory or observed in carefully controlled field studies. In the laboratory, animals push levers, pull strings, dig for food, swim in water mazes, or respond to images on computer screens to get information for discrimination, attention , memory , and categorization experiments. Careful field studies explore memory for food caches, navigation by stars, communication, tool use, identification of conspecifics , and many other matters. Studies often focus on

10370-562: The meantime, in Europe, ethology was making strides in studying a multitude of species and a plethora of behaviors. There was friction between the two disciplines where there should have been cooperation, but comparative psychologists refused, for the most part, to broaden their horizons. This state of affairs ended with the triumph of ethology over comparative psychology, culminating in the Nobel Prize being given to ethologists, combined with

10492-662: The more economical rat , which remained the almost invariable subject for the first half of the 20th century and continues to be used. Skinner introduced the use of pigeons , and they continue to be important in some fields. There has always been interest in studying various species of primate ; important contributions to social and developmental psychology were made by Harry F. Harlow 's studies of maternal deprivation in rhesus monkeys . Cross-fostering studies have shown similarities between human infants and infant chimpanzees. Kellogg and Kellogg (1933) aimed to look at heredity and environmental effects of young primates. They found that

10614-416: The most explicit dismissal of the idea that mental processes control behavior was the radical behaviorism of Skinner. This view seeks to explain behavior, including "private events" like mental images, solely by reference to the environmental contingencies impinging on the human or animal. Despite the predominantly behaviorist orientation of research before 1960, the rejection of mental processes in animals

10736-613: The naive human observer to be intelligent behavior may be strictly attributable to simple associations. According to Thorndike, using Morgan's Canon, the inference of animal reason, insight, or consciousness is unnecessary and misleading. At about the same time, I. P. Pavlov began his seminal studies of conditioned reflexes in dogs. Pavlov quickly abandoned attempts to infer canine mental processes; such attempts, he said, led only to disagreement and confusion. He was, however, willing to propose unseen physiological processes that might explain his observations. The work of Thorndike, Pavlov and

10858-539: The nectar of flowers, and they often return to the same flower, but only after the flower has had enough time to replenish its supply of nectar. In one experiment hummingbirds fed on artificial flowers that quickly emptied of nectar but were refilled at some fixed time (e.g. twenty minutes) later. The birds learned to come back to the flowers at about the right time, learning the refill rates of up to eight separate flowers and remembering how long ago they had visited each one. The details of interval timing have been studied in

10980-423: The object. Another way to produce attentional priming in search is to provide an advance signal that is associated with the target. For example, if a person hears a song sparrow he or she may be predisposed to detect a song sparrow in a shrub, or among other birds. A number of experiments have reproduced this effect in animal subjects. Still other experiments have explored nature of stimulus factors that affect

11102-399: The other hand, if the animal goes to a box that it has already emptied during the same test session, this indicates a failure of working memory. Various confounding factors, such as odor cues , are carefully controlled in such experiments. The water maze is used to test an animal's memory for spatial location and to discover how an animal is able to determine locations. Typically the maze

11224-515: The outcome was reversed again, and then again, and so on. Vaughan found that after 20 or more reversals, associating a reward with a few pictures in one set caused the birds to respond to the other pictures in that set without further reward as if they were thinking "if these pictures in set A bring food, the others in set A must also bring food." That is, the birds now categorized the pictures in each set as functionally equivalent. Several other procedures have yielded similar results. When tested in

11346-435: The part of the horse. Pfungst asked subjects to stand on his right and think "with a high degree of concentration" about a particular number, or a simple mathematical problem. Pfungst would then tap out the answer with his right hand. He frequently observed "a sudden slight upward jerk of the head" when reaching the final tap, and noted that this corresponded to the subject resuming the position they had adopted before thinking of

11468-473: The psychological state of a captive or domesticated animal must be taken into account if its behavior and health are to be understood and optimized. Common causes of disordered behavior in captive or pet animals are lack of stimulation, inappropriate stimulation, or overstimulation. These conditions can lead to disorders, unpredictable and unwanted behavior, and sometimes even physical symptoms and diseases. For example, rats who are exposed to loud music for

11590-408: The question. Some critics of Pfungst suggest that a proper way of validating the body language hypothesis should involve Pfungst acting out the same body language cues himself in order to reliably get Hans to give wrong answers. This would have validated the hypothesis that Hans is simply tapping in correspondence with certain body language cues, independently of the true answer; however, Pfungst never

11712-722: The rat presses the lever more and more until about 10 sec and then, when no food comes, gradually stops pressing. The time at which the rat presses most on these test trials is taken to be its estimate of the payoff time. Experiments using the peak procedure and other methods have shown that animals can time short intervals quite exactly, can time more than one event at once, and can integrate time with spatial and other cues. Such tests have also been used for quantitative tests of theories of animal timing, such as Gibbon's Scalar Expectancy Theory ("SET"), Killeen's Behavioral Theory of Timing, and Machado's Learning to Time model. No one theory has yet gained unanimous agreement. Although tool use

11834-418: The relative amount of time the animal spends swimming in the area where the platform had been located. Visual and other cues in and around the tank may be varied to assess the animal's reliance on landmarks and the geometric relations among them. The novel object recognition (NOR) test is an animal behavior test that is primarily used to assess memory alterations in rodents. It is a simple behavioral test that

11956-420: The results interpreted in terms of their different phylogenetic or ecological backgrounds. Behavioral ecology in the 1970s gave a more solid base of knowledge against which a true comparative psychology could develop. However, the broader use of the term "comparative psychology" is enshrined in the names of learned societies and academic journals, not to mention in the minds of psychologists of other specialisms, so

12078-450: The sole focus of comparative psychology and that intense focus on a single organism to understand its behavior is just as desirable; if not more so. Donald Dewsbury reviewed the works of several psychologists and their definitions and concluded that the object of comparative psychology is to establish principles of generality focusing on both proximate and ultimate causation . Using a comparative approach to behavior allows one to evaluate

12200-401: The spatial memory of scatter-hoarder animals such as Clark's nutcracker , certain jays , tits and certain squirrels , whose ecological niches require them to remember the locations of thousands of caches, often following radical changes in the environment. Memory has been widely investigated in foraging honeybees, Apis mellifera , which use both transient short-term working memory that

12322-405: The speed and accuracy of visual search. For example, the time taken to find a single target increases as the number of items in the visual field increases. This rise in reaction time is steep if the distracters are similar to the target, less steep if they are dissimilar, and may not occur if the distracters are very different from the target in form or color. Fundamental but difficult to define,

12444-401: The study of animal memory, and some of the phenomena characteristic of human short term memory (e.g. the serial position effect ) have been detected in animals, particularly monkeys . However most progress has been made in the analysis of spatial memory ; some of this work has sought to clarify the physiological basis of spatial memory and the role of the hippocampus ; other work has explored

12566-448: The target behavior from four different, complementary perspectives, developed by Niko Tinbergen. First, one may ask how pervasive the behavior is across species (i.e. how common is the behavior between animal species?). Second, one may ask how the behavior contributes to the lifetime reproductive success of the individuals demonstrating the behavior (i.e. does the behavior result in animals producing more offspring than animals not displaying

12688-408: The test stimulus has changed. Delayed response tasks are often used to study short-term memory in animals. Introduced by Hunter (1913), a typical delayed response task presents an animal with a stimulus such as colored light, and after a short time interval the animal chooses among alternatives that match the stimulus, or are related to the stimulus in some other way. In Hunter's studies, for example,

12810-405: The two also differs in important respects. Notably, much research with humans either studies or involves language, and much research with animals is related directly or indirectly to behaviors important to survival in natural settings. Following are summaries of some of the major areas of research in animal cognition. Animals process information from eyes, ears, and other sensory organs to perceive

12932-469: The variable stimulus but discrimination on the alternative stimulus worsens. These outcomes are consistent with the notion that attention is a limited resource that can be more or less focused among incoming stimuli. As noted above, the function of attention is to select information that is of special use to the animal. Visual search typically calls for this sort of selection, and search tasks have been used extensively in both humans and animals to determine

13054-425: The vehement opposition to Darwinism was the "anecdotal movement" led by George Romanes who set out to demonstrate that animals possessed a "rudimentary human mind". Romanes is most famous for two major flaws in his work: his focus on anecdotal observations and entrenched anthropomorphism . Near the end of the 19th century, several scientists existed whose work was also very influential. Douglas Alexander Spalding

13176-514: The visual sequence, although both bright and dim lights were equally associated with reward. More importantly, in a second experiment with auditory stimuli, rats responded correctly to sequences of novel stimuli that were arranged in the same order as those previously learned. Similar sequence learning has been demonstrated in birds and other animals as well. The categories that have been developed to analyze human memory ( short term memory , long term memory , working memory ) have been applied to

13298-479: The way attention and expectation affect the behavior of non-human animals, and much of this work suggests that attention operates in birds, mammals and reptiles in much the same way that it does in humans. Animals trained to discriminate between two stimuli, say black versus white, can be said to attend to the "brightness dimension", but this says little about whether this dimension is selected in preference to others. More enlightenment comes from experiments that allow

13420-434: The word". Although the field initially attempted to include a variety of species, by the early 1950s it had focused primarily on the white lab rat and the pigeon, and the topic of study was restricted to learning, usually in mazes. This stunted state of affairs was pointed out by Beach (1950) and although it was generally agreed with, no real change took place. He repeated the charges a decade later, again with no results. In

13542-415: Was Donald O. Hebb , who argued that "mind" is simply a name for processes in the head that control complex behavior, and that it is both necessary and possible to infer those processes from behavior. Animals came to be seen as "goal seeking agents that acquire, store, retrieve, and internally process information at many levels of cognitive complexity". The acceleration of research on animal cognition in

13664-561: Was able to successfully validate his hypothesis in this manner. After the investigations by Pfungst were done, von Osten, who was never persuaded by Pfungst's findings, continued to show Hans around Germany, attracting large and enthusiastic crowds. After Pfungst had become adept at giving Hans performances himself, and believed he was fully aware of the subtle cues which made them possible, he discovered that he would produce these cues involuntarily regardless of whether he wished to exhibit or suppress them. Recognition of this phenomenon has had

13786-471: Was acquired by several owners. After 1916, there is no record of him and his fate is unknown, but he was drafted into World War I as a military horse and "killed in action in 1916 or was consumed by hungry soldiers". The great public interest in Clever Hans led the German board of education to appoint a commission to investigate von Osten's scientific claims. Philosopher and psychologist Carl Stumpf formed

13908-637: Was also shown that these kids were more confident with themselves and able to be more empathic with other children. Furthermore, in an edition of Social Science and Medicine it was stated, "A random survey of 339 residents from Perth, Western Australia were selected from three suburbs and interviewed by telephone. Pet ownership was found to be positively associated with some forms of social contact and interaction, and with perceptions of neighborhood friendliness. After adjustment for demographic variables, pet owners scored higher on social capital and civic engagement scales." Results like these let us know that owning

14030-414: Was called the "first experimental biologist", and worked mostly with birds; studying instinct, imprinting, and visual and auditory development. Jacques Loeb emphasized the importance of objectively studying behavior, Sir John Lubbock is credited with first using mazes and puzzle devices to study learning and Conwy Lloyd Morgan is thought to be "the first ethologist in the sense in which we presently use

14152-510: Was caused by an attentional bias that improved detection of one type of insect while suppressing detection of others. This "attentional priming" is commonly said to result from a pretrial activation of a mental representation of the attended object, which Tinbergen called a "searching image". Tinbergen's field observations on priming have been supported by a number of experiments. For example, Pietrewicz and Kamil (1977, 1979) presented blue jays with pictures of tree trunks upon which rested either

14274-401: Was central in the development of comparative psychology; it is thought that psychology should be spoken in terms of "pre-" and "post-Darwin" because his contributions were so influential. Darwin's theory led to several hypotheses, one being that the factors that set humans apart, such as higher mental, moral and spiritual faculties, could be accounted for by evolutionary principles. In response to

14396-423: Was long assumed to be a uniquely human trait, there is now much evidence that many animals use tools, including mammals, birds, fish, cephalopods and insects. Discussions of tool use often involve a debate about what constitutes a "tool", and they often consider the relation of tool use to the animal's intelligence and brain size. Comparative psychologist Comparative psychology is the scientific study of

14518-515: Was looking at or who were able to "bark" the answer to questions like square roots while staring at their master's face, and so after refuting his initial suspicion of a fraud involving whispering or the like, began to consider accidental communication with Hans. Pfungst then examined the behaviour of the questioner in detail, and showed that as the horse's taps approached the right answer, the questioner's posture and facial expression changed in ways that were consistent with an increase in tension, which

14640-556: Was not universal during those years. Influential exceptions included, for example, Wolfgang Köhler and his insightful chimpanzees and Edward Tolman whose proposed cognitive map was a significant contribution to subsequent cognitive research in both humans and animals. Beginning around 1960, a "cognitive revolution" in research on humans gradually spurred a similar transformation of research with animals. Inference to processes not directly observable became acceptable and then commonplace. An important proponent of this shift in thinking

14762-435: Was present. The study concluded that when the experimenter provided a pointing gesture regardless of the owner’s knowledge, and that when no pointing cue was given to the dog, it only performed at chance level. This study proved that, for this pointing task, there was no Clever Hans effect affecting the dogs' performance, as long as the owners did not actively influence them. Similarly, a study done in 2013 also examined whether

14884-419: Was released when the horse made the final, correct tap. This provided a cue that the horse could use to stop tapping. The social communication systems of horses may depend on the detection of small postural changes, and this would explain why Hans so easily picked up on the cues given by von Osten, even if these cues were subconscious. Pfungst carried out laboratory tests with human subjects, in which he played

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