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97-485: Pathological visual illusions arise from pathological changes in the physiological visual perception mechanisms causing the aforementioned types of illusions; they are discussed e.g. under visual hallucinations . Optical illusions, as well as multi-sensory illusions involving visual perception, can also be used in the monitoring and rehabilitation of some psychological disorders, including phantom limb syndrome and schizophrenia . A familiar phenomenon and example for

194-426: A branch of biology . Anthropologist John Tooby and psychologist Leda Cosmides note: Evolutionary psychology is the long-forestalled scientific attempt to assemble out of the disjointed, fragmentary, and mutually contradictory human disciplines a single, logically integrated research framework for the psychological, social, and behavioral sciences – a framework that not only incorporates the evolutionary sciences on

291-460: A fear response is described as arising from a neurological computation that inputs the perceptional data, e.g. a visual image of a spider, and outputs the appropriate reaction, e.g. fear of possibly dangerous animals. Under this view, any domain-general learning is impossible because of the combinatorial explosion . Evolutionary Psychology specifies the domain as the problems of survival and reproduction. While philosophers have generally considered

388-983: A foundational, metatheoretical framework that integrates the entire field of psychology in the same way evolutionary biology has for biology. Evolutionary psychologists hold that behaviors or traits that occur universally in all cultures are good candidates for evolutionary adaptations, including the abilities to infer others' emotions, discern kin from non-kin, identify and prefer healthier mates, and cooperate with others. Findings have been made regarding human social behaviour related to infanticide , intelligence , marriage patterns, promiscuity , perception of beauty , bride price , and parental investment . The theories and findings of evolutionary psychology have applications in many fields, including economics , environment, health, law, management, psychiatry , politics , and literature . Criticism of evolutionary psychology involves questions of testability , cognitive and evolutionary assumptions (such as modular functioning of

485-488: A full and equal basis, but that systematically works out all of the revisions in existing belief and research practice that such a synthesis requires. Just as human physiology and evolutionary physiology have worked to identify physical adaptations of the body that represent "human physiological nature," the purpose of evolutionary psychology is to identify evolved emotional and cognitive adaptations that represent "human psychological nature." According to Steven Pinker , it

582-463: A higher-level integration of visual information beyond the primary visual cortex, V1 . Understanding how this specifically occurs in the brain may help in understanding how visual distortions , beyond imaginary hallucinations , affect schizophrenic patients. Additionally, evaluating the differences between how schizophrenic patients and unaffected individuals see illusions may enable researchers to better identify where specific illusions are processed in

679-522: A large object, like an airplane, to move more slowly than smaller objects, like a car, although the larger object is actually moving faster. The phi phenomenon is yet another example of how the brain perceives motion, which is most often created by blinking lights in close succession. The ambiguity of direction of motion due to lack of visual references for depth is shown in the spinning dancer illusion . The spinning dancer appears to be moving clockwise or counterclockwise depending on spontaneous activity in

776-491: A meaningful whole. Gestalt organization can be used to explain many illusions including the rabbit–duck illusion where the image as a whole switches back and forth from being a duck then being a rabbit and why in the figure–ground illusion the figure and ground are reversible. In addition, gestalt theory can be used to explain the illusory contours in the Kanizsa's triangle . A floating white triangle, which does not exist,

873-446: A medical practitioner. Etiologies associated with pathological visual illusions include multiple types of ocular disease , migraines , hallucinogen persisting perception disorder , head trauma , and prescription drugs . If a medical work-up does not reveal a cause of the pathological visual illusions, the idiopathic visual disturbances could be analogous to the altered excitability state seen in visual aura with no migraine headache. If

970-432: A more imaginative take on optical illusions, saying that they are due to a neural lag which most humans experience while awake. When light hits the retina, about one-tenth of a second goes by before the brain translates the signal into a visual perception of the world. Scientists have known of the lag, yet they have debated how humans compensate, with some proposing that our motor system somehow modifies our movements to offset

1067-477: A new and different environment can create a mismatch. Because humans are mostly adapted to Pleistocene environments, psychological mechanisms sometimes exhibit "mismatches" to the modern environment. One example is the fact that although about 10,000 people are killed with guns in the US annually, whereas spiders and snakes kill only a handful, people nonetheless learn to fear spiders and snakes about as easily as they do

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1164-670: A new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Two of his later books were devoted to the study of animal emotions and psychology; The Descent of Man, and Selection in Relation to Sex in 1871 and The Expression of the Emotions in Man and Animals in 1872. Darwin's work inspired William James 's functionalist approach to psychology. Darwin's theories of evolution, adaptation, and natural selection have provided insight into why brains function

1261-461: A northern climate to the equator will have darker skin. The mechanisms regulating their pigmentation do not change; rather the input to those mechanisms change, resulting in different outputs. One of the tasks of evolutionary psychology is to identify which psychological traits are likely to be adaptations, byproducts or random variation. George C. Williams suggested that an "adaptation is a special and onerous concept that should only be used where it

1358-427: A physical visual illusion is when mountains appear to be much nearer in clear weather with low humidity ( Foehn ) than they are. This is because haze is a cue for depth perception , signalling the distance of far-away objects ( Aerial perspective ). The classical example of a physical illusion is when a stick that is half immersed in water appears bent. This phenomenon was discussed by Ptolemy ( c.  150 ) and

1455-477: A pointed gun, and more easily than an unpointed gun, rabbits or flowers. A potential explanation is that spiders and snakes were a threat to human ancestors throughout the Pleistocene, whereas guns (and rabbits and flowers) were not. There is thus a mismatch between humans' evolved fear-learning psychology and the modern environment. This mismatch also shows up in the phenomena of the supernormal stimulus ,

1552-436: A popular but recent theory of lightness illusions, states that any region belongs to one or more frameworks, created by gestalt grouping principles, and within each frame is independently anchored to both the highest luminance and the surround luminance. A spot's lightness is determined by the average of the values computed in each framework. Illusions can be based on an individual's ability to see in three dimensions even though

1649-403: A sign that the body schema , or an individual's sense of their own body and its parts, progressively adapts to the post-amputation state. Essentially, the amputees were learning to no longer respond to sensations near what had once been their arm. As a result, many have suggested the use of RHI as a tool for monitoring an amputee's progress in reducing their phantom limb sensations and adjusting to

1746-455: A slightly different perspective by trying to explain how human behavior is a product of two different and interacting evolutionary processes: genetic evolution and cultural evolution . DIT is seen by some as a "middle-ground" between views that emphasize human universals versus those that emphasize cultural variation. The theories on which evolutionary psychology is based originated with Charles Darwin's work, including his speculations about

1843-451: A species and should solve important problems of survival and reproduction . Evolutionary psychologists seek to understand psychological mechanisms by understanding the survival and reproductive functions they might have served over the course of evolutionary history. These might include abilities to infer others' emotions, discern kin from non-kin, identify and prefer healthier mates, cooperate with others and follow leaders. Consistent with

1940-437: A stimulus that elicits a response more strongly than the stimulus for which the response evolved. The term was coined by Niko Tinbergen to refer to non-human animal behavior, but psychologist Deirdre Barrett said that supernormal stimulation governs the behavior of humans as powerfully as that of other animals. She explained junk food as an exaggerated stimulus to cravings for salt, sugar, and fats, and she says that television

2037-548: A subfield of psychohistory collapsed under the weight of its presuppositions." She concludes that, as of 2014, the "'iron curtain' between historians and psychology...remains standing." Not all traits of organisms are evolutionary adaptations. As noted in the table below, traits may also be exaptations , byproducts of adaptations (sometimes called "spandrels"), or random variation between individuals. Psychological adaptations are hypothesized to be innate or relatively easy to learn and to manifest in cultures worldwide. For example,

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2134-417: A vast period of time to solve the recurrent information-processing problems faced by our ancestors. These problems involve food choices, social hierarchies, distributing resources to offspring, and selecting mates. Proponents suggest that it seeks to integrate psychology into the other natural sciences, rooting it in the organizing theory of biology ( evolutionary theory ), and thus understanding psychology as

2231-536: Is heuristic in that it may generate hypotheses that might not be developed from other theoretical approaches. One of the main goals of adaptationist research is to identify which organismic traits are likely to be adaptations, and which are byproducts or random variations. As noted earlier, adaptations are expected to show evidence of complexity, functionality, and species universality, while byproducts or random variation will not. In addition, adaptations are expected to be presented as proximate mechanisms that interact with

2328-424: Is "not a single theory but a large set of hypotheses" and a term that "has also come to refer to a particular way of applying evolutionary theory to the mind, with an emphasis on adaptation, gene-level selection, and modularity." Evolutionary psychology adopts an understanding of the mind that is based on the computational theory of mind . It describes mental processes as computational operations, so that, for example,

2425-401: Is 3D volumetric in appearance. Coloration consists of an assimilation of color radiating from a thin-colored edge lining a darker chromatic contour. The water-color illusion describes how the human mind perceives the wholeness of an object such as top-down processing. Thus, contextual factors play into perceiving the brightness of an object. Just as it perceives color and brightness constancies,

2522-504: Is a mismatch. His argument is that humans are not adapted to work in large, anonymous bureaucratic structures with formal hierarchies. The human mind still responds to personalized, charismatic leadership primarily in the context of informal, egalitarian settings. Hence the dissatisfaction and alienation that many employees experience. Salaries, bonuses and other privileges exploit instincts for relative status, which attract particularly males to senior executive positions. Evolutionary theory

2619-476: Is also used in film by the technique of forced perspective . Op art is a style of art that uses optical illusions to create an impression of movement, or hidden images and patterns. Trompe-l'œil uses realistic imagery to create the optical illusion that depicted objects exist in three dimensions. Tourists attractions employing large-scale illusory art allowing visitors to photograph themselves in fantastic scenes have opened in several Asian countries, such as

2716-426: Is an exaggeration of social cues of laughter, smiling faces and attention-grabbing action. Magazine centerfolds and double cheeseburgers pull instincts intended for an environment of evolutionary adaptedness where breast development was a sign of health, youth and fertility in a prospective mate, and fat was a rare and vital nutrient. The psychologist Mark van Vugt recently argued that modern organizational leadership

2813-410: Is dependent on whether early childhood caregivers could be trusted to provide reliable assistance and attention. The adaptation for skin to tan is conditional to exposure to sunlight; this is an example of another facultative adaptation. When a psychological adaptation is facultative, evolutionary psychologists concern themselves with how developmental and environmental inputs influence the expression of

2910-414: Is really necessary." As noted by Williams and others, adaptations can be identified by their improbable complexity, species universality, and adaptive functionality. A question that may be asked about an adaptation is whether it is generally obligate (relatively robust in the face of typical environmental variation) or facultative (sensitive to typical environmental variation). The sweet taste of sugar and

3007-523: Is seen. The brain has a need to see familiar simple objects and has a tendency to create a "whole" image from individual elements. Gestalt means "form" or "shape" in German. However, another explanation of the Kanizsa's triangle is based in evolutionary psychology and the fact that in order to survive it was important to see form and edges. The use of perceptual organization to create meaning out of stimuli

Optical illusion - Misplaced Pages Continue

3104-433: Is that a stimulus follows its individual dedicated neural path in the early stages of visual processing and that intense or repetitive activity in that or interaction with active adjoining channels causes a physiological imbalance that alters perception. The Hermann grid illusion and Mach bands are two illusions that are often explained using a biological approach. Lateral inhibition , where in receptive fields of

3201-462: Is the principle behind other well-known illusions including impossible objects . The brain makes sense of shapes and symbols putting them together like a jigsaw puzzle, formulating that which is not there to that which is believable. The gestalt principles of perception govern the way different objects are grouped. Good form is where the perceptual system tries to fill in the blanks in order to see simple objects rather than complex objects. Continuity

3298-406: Is where the perceptual system tries to disambiguate which segments fit together into continuous lines. Proximity is where objects that are close together are associated. Similarity is where objects that are similar are seen as associated. Some of these elements have been successfully incorporated into quantitative models involving optimal estimation or Bayesian inference. The double-anchoring theory,

3395-487: The Trickeye Museum and Hong Kong 3D Museum . The hypothesis claims that visual illusions occur because the neural circuitry in our visual system evolves, by neural learning, to a system that makes very efficient interpretations of usual 3D scenes based in the emergence of simplified models in our brain that speed up the interpretation process but give rise to optical illusions in unusual situations. In this sense,

3492-1014: The parietal cortex . In another study on the motion-induced blindness (MIB) illusion (pictured right), schizophrenic patients continued to perceive stationary visual targets even when observing distracting motion stimuli, unlike neurotypical controls , who experienced motion induced blindness. The schizophrenic test subjects demonstrated impaired cognitive organization, meaning they were less able to coordinate their processing of motion cues and stationary image cues. Artists who have worked with optical illusions include M. C. Escher , Bridget Riley , Salvador Dalí , Giuseppe Arcimboldo , Patrick Bokanowski , Marcel Duchamp , Jasper Johns , Oscar Reutersvärd , Victor Vasarely and Charles Allan Gilbert . Contemporary artists who have experimented with illusions include Jonty Hurwitz , Sandro del Prete , Octavio Ocampo , Dick Termes , Shigeo Fukuda , Patrick Hughes , István Orosz , Rob Gonsalves , Gianni A. Sarcone , Ben Heine and Akiyoshi Kitaoka . Optical illusion

3589-409: The visual streams. One study on schizophrenic patients found that they were extremely unlikely to be fooled by a three dimensional optical illusion, the hollow face illusion , unlike neurotypical volunteers. Based on fMRI data, researchers concluded that this resulted from a disconnection between their systems for bottom-up processing of visual cues and top-down interpretations of those cues in

3686-459: The " standard social science model ," according to which the mind is a general-purpose cognition device shaped almost entirely by culture. Evolutionary psychology argues that to properly understand the functions of the brain, one must understand the properties of the environment in which the brain evolved. That environment is often referred to as the "environment of evolutionary adaptedness". The idea of an environment of evolutionary adaptedness

3783-516: The "why?" questions, while traditional psychology focuses on the "how?" questions. Evolutionary psychology is founded on several core premises. Evolutionary psychology has its historical roots in Charles Darwin 's theory of natural selection. In The Origin of Species , Darwin predicted that psychology would develop an evolutionary basis: In the distant future I see open fields for far more important researches. Psychology will be based on

3880-509: The 1930s and 1940s. In the 1930s the study of animal behavior (ethology) emerged with the work of the Dutch biologist Nikolaas Tinbergen and the Austrian biologists Konrad Lorenz and Karl von Frisch . W.D. Hamilton's (1964) papers on inclusive fitness and Robert Trivers 's (1972) theories on reciprocity and parental investment helped to establish evolutionary thinking in psychology and

3977-530: The 1990s made some explorations in historical events, but the response from historical experts was highly negative and there has been little effort to continue that line of research. Historian Lynn Hunt says that the historians complained that the researchers: have read the wrong studies, misinterpreted the results of experiments, or worse yet, turned to neuroscience looking for a universalizing, anti-representational and anti-intentional ontology to bolster their claims. Hunt states that "the few attempts to build up

Optical illusion - Misplaced Pages Continue

4074-476: The 19th century by the German physicist and physician Hermann Helmholtz . Cognitive illusions are commonly divided into ambiguous illusions , distorting illusions, paradox illusions, or fiction illusions. To make sense of the world it is necessary to organize incoming sensations into information which is meaningful. Gestalt psychologists believe one way this is done is by perceiving individual sensory stimuli as

4171-607: The 3D environment around them. After a long process of learning, an internal representation of the world emerges that is well-adjusted to the perceived data coming from closer objects. The representation of distant objects near the horizon is less "adequate". In fact, it is not only the Moon that seems larger when we perceive it near the horizon. In a photo of a distant scene, all distant objects are perceived as smaller than when we observe them directly using our vision. Visual perception Too Many Requests If you report this error to

4268-583: The Wikimedia System Administrators, please include the details below. Request from 172.68.168.133 via cp1102 cp1102, Varnish XID 550346445 Upstream caches: cp1102 int Error: 429, Too Many Requests at Thu, 28 Nov 2024 05:53:42 GMT Evolutionary psychology Evolutionary psychology is a theoretical approach in psychology that examines cognition and behavior from a modern evolutionary perspective. It seeks to identify human psychological adaptations with regards to

4365-548: The ability of toddlers to learn a language with virtually no training is likely to be a psychological adaptation. On the other hand, ancestral humans did not read or write, thus today, learning to read and write requires extensive training, and presumably involves the repurposing of cognitive capacities that evolved in response to selection pressures unrelated to written language. However, variations in manifest behavior can result from universal mechanisms interacting with different local environments. For example, Caucasians who move from

4462-422: The adaptation. Evolutionary psychologists hold that behaviors or traits that occur universally in all cultures are good candidates for evolutionary adaptations. Cultural universals include behaviors related to language, cognition, social roles, gender roles, and technology. Evolved psychological adaptations (such as the ability to learn a language) interact with cultural inputs to produce specific behaviors (e.g.,

4559-484: The adaptation. Humans, the genus Homo , appeared between 1.5 and 2.5 million years ago, a time that roughly coincides with the start of the Pleistocene 2.6 million years ago. Because the Pleistocene ended a mere 12,000 years ago, most human adaptations either newly evolved during the Pleistocene, or were maintained by stabilizing selection during the Pleistocene. Evolutionary psychology, therefore, proposes that

4656-404: The ancestral problems they evolved to solve. In this framework, psychological traits and mechanisms are either functional products of natural and sexual selection or non-adaptive by-products of other adaptive traits. Adaptationist thinking about physiological mechanisms, such as the heart , lungs , and the liver , is common in evolutionary biology . Evolutionary psychologists apply

4753-475: The biological basis of all social behavior" and in 1978 as "the extension of population biology and evolutionary theory to social organization." Secondly, there was behavioral ecology which placed less emphasis on social behavior; it focused on the ecological and evolutionary basis of animal and human behavior. In the 1970s and 1980s university departments began to include the term evolutionary biology in their titles. The modern era of evolutionary psychology

4850-598: The brain has the ability to understand familiar objects as having a consistent shape or size. For example, a door is perceived as a rectangle regardless of how the image may change on the retina as the door is opened and closed. Unfamiliar objects, however, do not always follow the rules of shape constancy and may change when the perspective is changed. The Shepard tables illusion is an example of an illusion based on distortions in shape constancy. Researcher Mark Changizi of Rensselaer Polytechnic Institute in New York has

4947-400: The brain where perception is subjective. Recent studies show on the fMRI that there are spontaneous fluctuations in cortical activity while watching this illusion, particularly the parietal lobe because it is involved in perceiving movement. Perceptual constancies are sources of illusions. Color constancy and brightness constancy are responsible for the fact that a familiar object will appear

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5044-442: The brain, and large uncertainty about the ancestral environment), importance of non-genetic and non-adaptive explanations, as well as political and ethical issues due to interpretations of research results. Evolutionary psychologists frequently engage with and respond to such criticisms. Its central assumption is that the human brain is composed of a large number of specialized mechanisms that were shaped by natural selection over

5141-559: The characteristics of an evolved adaptation (complexity and universality). Margie Profet hypothesized that the function was to avoid the ingestion of toxins during early pregnancy that could damage fetus (but which are otherwise likely to be harmless to healthy non-pregnant women). Corresponding Neurological Modules. Evolutionary psychology and cognitive neuropsychology are mutually compatible – evolutionary psychology helps to identify psychological adaptations and their ultimate, evolutionary functions, while neuropsychology helps to identify

5238-445: The cognitive processes hypothesis can be considered a framework for an understanding of optical illusions as the signature of the empirical statistical way vision has evolved to solve the inverse problem. Research indicates that 3D vision capabilities emerge and are learned jointly with the planning of movements. That is, as depth cues are better perceived, individuals can develop more efficient patterns of movement and interaction within

5335-464: The converging parallel lines tell the brain that the image higher in the visual field is farther away, therefore, the brain perceives the image to be larger, although the two images hitting the retina are the same size. The optical illusion seen in a diorama / false perspective also exploits assumptions based on monocular cues of depth perception . The M.C. Escher painting Waterfall exploits rules of depth and proximity and our understanding of

5432-482: The course of human evolutionary history. Domain-general mechanisms, on the other hand, are proposed to deal with evolutionary novelty. Evolutionary psychology has roots in cognitive psychology and evolutionary biology but also draws on behavioral ecology , artificial intelligence , genetics , ethology , anthropology , archaeology , biology, ecopsycology and zoology . It is closely linked to sociobiology , but there are key differences between them including

5529-448: The delay. Changizi asserts that the human visual system has evolved to compensate for neural delays by generating images of what will occur one-tenth of a second into the future. This foresight enables humans to react to events in the present, enabling humans to perform reflexive acts like catching a fly ball and to maneuver smoothly through a crowd. In an interview with ABC Changizi said, "Illusions occur when our brains attempt to perceive

5626-576: The development of an individual may alter life-history trajectories. Evolutionary psychologists use several strategies to develop and test hypotheses about whether a psychological trait is likely to be an evolved adaptation. Buss (2011) notes that these methods include: Cross-cultural Consistency. Characteristics that have been demonstrated to be cross-cultural human universals such as smiling, crying, facial expressions are presumed to be evolved psychological adaptations. Several evolutionary psychologists have collected massive datasets from cultures around

5723-517: The development of culture, and culture, in turn, affecting human evolution on a genetic level, in a similar way to the Baldwin effect . Evolutionary psychology is based on the hypothesis that, just like hearts, lungs, livers, kidneys, and immune systems, cognition has a functional structure that has a genetic basis, and therefore has evolved by natural selection. Like other organs and tissues, this functional structure should be universally shared amongst

5820-404: The emphasis on domain-specific rather than domain-general mechanisms, the relevance of measures of current fitness , the importance of mismatch theory , and psychology rather than behavior. Nikolaas Tinbergen 's four categories of questions can help to clarify the distinctions between several different, but complementary, types of explanations. Evolutionary psychology focuses primarily on

5917-542: The environment in either a generally obligate or facultative fashion (see above). Evolutionary psychologists are also interested in identifying these proximate mechanisms (sometimes termed "mental mechanisms" or "psychological adaptations") and what type of information they take as input, how they process that information, and their outputs. Evolutionary developmental psychology , or "evo-devo," focuses on how adaptations may be activated at certain developmental times (e.g., losing baby teeth, adolescence, etc.) or how events during

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6014-607: The environment in which an organism evolved, the environment of evolutionary adaptedness. Sexual selection provides organisms with adaptations related to mating. For male mammals , which have a relatively high maximal potential reproduction rate, sexual selection leads to adaptations that help them compete for females. For female mammals, with a relatively low maximal potential reproduction rate, sexual selection leads to choosiness, which helps females select higher quality mates. Charles Darwin described both natural selection and sexual selection, and he relied on group selection to explain

6111-530: The environment of evolutionary adaptedness. Unfortunately, the few surviving hunter-gatherer societies are different from each other, and they have been pushed out of the best land and into harsh environments, so it is not clear how closely they reflect ancestral culture. However, all around the world small-band hunter-gatherers offer a similar developmental system for the young ("hunter-gatherer childhood model," Konner, 2005; "evolved developmental niche" or "evolved nest;" Narvaez et al., 2013). The characteristics of

6208-443: The evolution of altruistic (self-sacrificing) behavior. But group selection was considered a weak explanation, because in any group the less altruistic individuals will be more likely to survive, and the group will become less self-sacrificing as a whole. In 1964, the evolutionary biologist William D. Hamilton proposed inclusive fitness theory, emphasizing a gene-centered view of evolution . Hamilton noted that genes can increase

6305-469: The evolutionary origins of social instincts in humans. Modern evolutionary psychology, however, is possible only because of advances in evolutionary theory in the 20th century. Evolutionary psychologists say that natural selection has provided humans with many psychological adaptations, in much the same way that it generated humans' anatomical and physiological adaptations. As with adaptations in general, psychological adaptations are said to be specialized for

6402-601: The evolved mechanism in depression. Clinical depression is maladaptive and should have evolutionary approaches so it can become adaptive. Over the centuries animals and humans have gone through hard times to stay alive, which made our fight or flight senses evolve tremendously. For instances, mammalians have separation anxiety from their guardians which causes distress and sends signals to their hypothalamic pituitary adrenal axis, and emotional/behavioral changes. Going through these types of circumstances helps mammals cope with separation anxiety. Proponents of evolutionary psychology in

6499-403: The eye will compensate for color contrast depending on the color cast of the surrounding area. In addition to the gestalt principles of perception, water-color illusions contribute to the formation of optical illusions. Water-color illusions consist of object-hole effects and coloration. Object-hole effects occur when boundaries are prominent where there is a figure and background with a hole that

6596-494: The figure is static, we misperceive the straight lines as curved ones. Changizi said: Evolution has seen to it that geometric drawings like this elicit in us premonitions of the near future. The converging lines toward a vanishing point (the spokes) are cues that trick our brains into thinking we are moving forward—as we would in the real world, where the door frame (a pair of vertical lines) seems to bow out as we move through it—and we try to perceive what that world will look like in

6693-478: The future, and those perceptions don't match reality." For example, an illusion called the Hering illusion looks like bicycle spokes around a central point, with vertical lines on either side of this central, so-called vanishing point. The illusion tricks us into thinking we are looking at a perspective picture, and thus according to Changizi, switches on our future-seeing abilities. Since we are not actually moving and

6790-748: The human mind to include broad faculties, such as reason and lust, evolutionary psychologists describe evolved psychological mechanisms as narrowly focused to deal with specific issues, such as catching cheaters or choosing mates. The discipline sees the human brain as having evolved specialized functions, called cognitive modules , or psychological adaptations which are shaped by natural selection. Examples include language-acquisition modules , incest-avoidance mechanisms , cheater-detection mechanisms , intelligence and sex-specific mating preferences, foraging mechanisms, alliance-tracking mechanisms, agent-detection mechanisms, and others. Some mechanisms, termed domain-specific , deal with recurrent adaptive problems over

6887-452: The image hitting the retina is only two dimensional. The Ponzo illusion is an example of an illusion which uses monocular cues of depth perception to fool the eye. But even with two-dimensional images, the brain exaggerates vertical distances when compared with horizontal distances, as in the vertical–horizontal illusion where the two lines are exactly the same length. In the Ponzo illusion

6984-625: The majority of human psychological mechanisms are adapted to reproductive problems frequently encountered in Pleistocene environments. In broad terms, these problems include those of growth, development, differentiation, maintenance, mating, parenting, and social relationships. The environment of evolutionary adaptedness is significantly different from modern society. The ancestors of modern humans lived in smaller groups, had more cohesive cultures, and had more stable and rich contexts for identity and meaning. Researchers look to existing hunter-gatherer societies for clues as to how hunter-gatherers lived in

7081-399: The new state of their body. Other research used RHI in the rehabilitation of amputees with prosthetic limbs. After prolonged exposure to RHI, the amputees gradually stopped feeling a dissociation between the prosthetic (which resembled the rubber hand) and the rest of their body. This was thought to be because they adjusted to responding to and moving a limb that did not feel as connected to

7178-894: The next instant. A pathological visual illusion is a distortion of a real external stimulus and is often diffuse and persistent. Pathological visual illusions usually occur throughout the visual field, suggesting global excitability or sensitivity alterations. Alternatively visual hallucination is the perception of an external visual stimulus where none exists. Visual hallucinations are often from focal dysfunction and are usually transient. Types of visual illusions include oscillopsia , halos around objects , illusory palinopsia ( visual trailing , light streaking , prolonged indistinct afterimages ), akinetopsia , visual snow , micropsia , macropsia , teleopsia , pelopsia , metamorphopsia , dyschromatopsia , intense glare , blue field entoptic phenomenon , and purkinje trees . These symptoms may indicate an underlying disease state and necessitate seeing

7275-652: The niche are largely the same as for social mammals, who evolved over 30 million years ago: soothing perinatal experience, several years of on-request breastfeeding, nearly constant affection or physical proximity, responsiveness to need (mitigating offspring distress), self-directed play, and for humans, multiple responsive caregivers. Initial studies show the importance of these components in early life for positive child outcomes. Evolutionary psychologists sometimes look to chimpanzees, bonobos, and other great apes for insight into human ancestral behavior. Since an organism's adaptations were suited to its ancestral environment,

7372-695: The organism's close relatives so much that it more than compensates for the individual animal's sacrifice. Inclusive fitness theory resolved the issue of how altruism can evolve. Other theories also help explain the evolution of altruistic behavior, including evolutionary game theory , tit-for-tat reciprocity, and generalized reciprocity. These theories help to explain the development of altruistic behavior, and account for hostility toward cheaters (individuals that take advantage of others' altruism). Several mid-level evolutionary theories inform evolutionary psychology. The r/K selection theory proposes that some species prosper by having many offspring, while others follow

7469-465: The other social sciences. In 1975, Edward O. Wilson combined evolutionary theory with studies of animal and social behavior, building on the works of Lorenz and Tinbergen, in his book Sociobiology: The New Synthesis . In the 1970s, two major branches developed from ethology. Firstly, the study of animal social behavior (including humans) generated sociobiology , defined by its pre-eminent proponent Edward O. Wilson in 1975 as "the systematic study of

7566-445: The pain of hitting one's knee against concrete are the result of fairly obligate psychological adaptations; typical environmental variability during development does not much affect their operation. By contrast, facultative adaptations are somewhat like "if-then" statements. For example, adult attachment style seems particularly sensitive to early childhood experiences. As adults, the propensity to develop close, trusting bonds with others

7663-428: The physical world to create an illusion. Like depth perception , motion perception is responsible for a number of sensory illusions. Film animation is based on the illusion that the brain perceives a series of slightly varied images produced in rapid succession as a moving picture. Likewise, when we are moving, as we would be while riding in a vehicle, stable surrounding objects may appear to move. We may also perceive

7760-428: The primary streams of developmental , social and cognitive psychology. Establishing some measure of the relative influence of genetics and environment on behavior has been at the core of behavioral genetics and its variants, notably studies at the molecular level that examine the relationship between genes, neurotransmitters and behavior. Dual inheritance theory (DIT), developed in the late 1970s and early 1980s, has

7857-447: The proximate manifestations of these adaptations. Current Evolutionary Adaptiveness. In addition to evolutionary models that suggest evolution occurs across large spans of time, recent research has demonstrated that some evolutionary shifts can be fast and dramatic. Consequently, some evolutionary psychologists have focused on the impact of psychological traits in the current environment. Such research can be used to inform estimates of

7954-419: The replication of copies of themselves into the next generation by influencing the organism's social traits in such a way that (statistically) results in helping the survival and reproduction of other copies of the same genes (most simply, identical copies in the organism's close relatives). According to Hamilton's rule , self-sacrificing behaviors (and the genes influencing them) can evolve if they typically help

8051-406: The rest of their body or senses. RHI may also be used to diagnose certain disorders related to impaired proprioception or impaired sense of touch in non-amputees. Schizophrenia , a mental disorder often marked by hallucinations , also decreases a person's ability to perceive high-order optical illusions. This is because schizophrenia impairs one's capacity to perform top-down processing and

8148-538: The retina receptor signals from light and dark areas compete with one another, has been used to explain why we see bands of increased brightness at the edge of a color difference when viewing Mach bands. Once a receptor is active, it inhibits adjacent receptors. This inhibition creates contrast, highlighting edges. In the Hermann grid illusion, the gray spots that appear at the intersections at peripheral locations are often explained to occur because of lateral inhibition by

8245-442: The same color regardless of the amount of light or color of light reflecting from it. An illusion of color difference or luminosity difference can be created when the luminosity or color of the area surrounding an unfamiliar object is changed. The luminosity of the object will appear brighter against a black field (that reflects less light) than against a white field, even though the object itself did not change in luminosity. Similarly,

8342-557: The same thinking in psychology, arguing that just as the heart evolved to pump blood, the liver evolved to detoxify poisons, and the kidneys evolved to filter turbid fluids there is modularity of mind in that different psychological mechanisms evolved to solve different adaptive problems. These evolutionary psychologists argue that much of human behavior is the output of psychological adaptations that evolved to solve recurrent problems in human ancestral environments. Some evolutionary psychologists argue that evolutionary theory can provide

8439-607: The specific language learned). Basic gender differences, such as greater eagerness for sex among men and greater coyness among women, are explained as sexually dimorphic psychological adaptations that reflect the different reproductive strategies of males and females. It has been found that both male and female personality traits differ on a large spectrum. Males had a higher rate of traits relating to dominance, tension, and directness. Females had higher rates organizational behavior and more emotional based characteristics. Evolutionary psychologists contrast their approach to what they term

8536-958: The strategy of having fewer offspring but investing much more in each one. Humans follow the second strategy. Parental investment theory explains how parents invest more or less in individual offspring based on how successful those offspring are likely to be, and thus how much they might improve the parents' inclusive fitness. According to the Trivers–Willard hypothesis , parents in good conditions tend to invest more in sons (who are best able to take advantage of good conditions), while parents in poor conditions tend to invest more in daughters (who are best able to have successful offspring even in poor conditions). According to life history theory , animals evolve life histories to match their environments, determining details such as age at first reproduction and number of offspring. Dual inheritance theory posits that genes and human culture have interacted, with genes affecting

8633-469: The surround in larger receptive fields. However, lateral inhibition as an explanation of the Hermann grid illusion has been disproved . More recent empirical approaches to optical illusions have had some success in explaining optical phenomena with which theories based on lateral inhibition have struggled. Cognitive illusions are assumed to arise by interaction with assumptions about the world, leading to "unconscious inferences", an idea first suggested in

8730-401: The syndrome actually responded to RHI more strongly than controls, an effect that was often consistent for both the sides of the intact and the amputated arm. However, in some studies, amputees actually had stronger responses to RHI on their intact arm, and more recent amputees responded to the illusion better than amputees who had been missing an arm for years or more. Researchers believe this is

8827-863: The theory of natural selection, evolutionary psychology sees humans as often in conflict with others, including mates and relatives. For instance, a mother may wish to wean her offspring from breastfeeding earlier than does her infant, which frees up the mother to invest in additional offspring. Evolutionary psychology also recognizes the role of kin selection and reciprocity in evolving prosocial traits such as altruism. Like chimpanzees and bonobos , humans have subtle and flexible social instincts, allowing them to form extended families, lifelong friendships, and political alliances. In studies testing theoretical predictions, evolutionary psychologists have made modest findings on topics such as infanticide, intelligence, marriage patterns, promiscuity, perception of beauty, bride price and parental investment. Another example would be

8924-499: The visual illusions are diffuse and persistent, they often affect the patient's quality of life. These symptoms are often refractory to treatment and may be caused by any of the aforementioned etiologies, but are often idiopathic. There is no standard treatment for these visual disturbances. The rubber hand illusion (RHI), a multi-sensory illusion involving both visual perception and touch , has been used to study how phantom limb syndrome affects amputees over time. Amputees with

9021-400: The way they do. The content of evolutionary psychology has derived from, on the one hand, the biological sciences (especially evolutionary theory as it relates to ancient human environments, the study of paleoanthropology and animal behavior) and, on the other, the human sciences, especially psychology. Evolutionary biology as an academic discipline emerged with the modern synthesis in

9118-563: The world to assess cross-cultural universality. Function to Form (or "problem to solution"). The fact that males, but not females, risk potential misidentification of genetic offspring (referred to as "paternity uncertainty") led evolutionary psychologists to hypothesize that, compared to females, male jealousy would be more focused on sexual, rather than emotional, infidelity. Form to Function (reverse-engineering – or "solution to problem"). Morning sickness , and associated aversions to certain types of food, during pregnancy seemed to have

9215-419: Was first explored as a part of attachment theory by John Bowlby . This is the environment to which a particular evolved mechanism is adapted. More specifically, the environment of evolutionary adaptedness is defined as the set of historically recurring selection pressures that formed a given adaptation, as well as those aspects of the environment that were necessary for the proper development and functioning of

9312-444: Was often a prototypical example for an illusion. Physiological illusions, such as the afterimages following bright lights, or adapting stimuli of excessively longer alternating patterns ( contingent perceptual aftereffect ), are presumed to be the effects on the eyes or brain of excessive stimulation or interaction with contextual or competing stimuli of a specific type—brightness, color, position, tile, size, movement, etc. The theory

9409-656: Was ushered in, in particular, by Donald Symons ' 1979 book The Evolution of Human Sexuality and Leda Cosmides and John Tooby 's 1992 book The Adapted Mind . David Buller observed that the term "evolutionary psychology" is sometimes seen as denoting research based on the specific methodological and theoretical commitments of certain researchers from the Santa Barbara school (University of California), thus some evolutionary psychologists prefer to term their work "human ecology", "human behavioural ecology" or "evolutionary anthropology" instead. From psychology there are

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