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Perception () is the organization, identification, and interpretation of sense information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system, which in turn result from physical or chemical stimulation of the sensory system.Goldstein (2009) pp. 5–7 Visual system involves light striking the retina of the eye; smell is mediated by odor molecules; and hearing involves Sound wave.
Perception is not only the passive receipt of these signals, but it is also shaped by the recipient's learning, memory, expectation, and attention.Richard Gregory. "Perception" in Gregory, Zangwill (1987) pp. 598–601. Sensory input is a process that transforms this low-level information to higher-level information (e.g., extracts shapes for object recognition). The following process connects a person's concepts and expectations (or knowledge) with restorative and selective mechanisms, such as attention, that influence perception.
Perception depends on complex functions of the nervous system, but subjectively seems mostly effortless because this processing happens outside Consciousness awareness. Since the rise of experimental psychology in the 19th century, psychology's understanding of perception has progressed by combining a variety of techniques. Psychophysics quantitatively describes the relationships between the physical qualities of the sensory input and perception.Gustav Fechner. Elemente der Psychophysik. Leipzig 1860. Sensory neuroscience studies the neural mechanisms underlying perception. Perceptual systems can also be studied , in terms of the information they process. Perceptual issues in philosophy include the extent to which sensory qualities such as sound, smell or color exist in objective reality rather than in the mind of the perceiver.
Although people traditionally viewed the senses as passive receptors, the study of and has demonstrated that the brain's perceptual systems actively and pre-consciously attempt to make sense of their input. There is still active debate about the extent to which perception is an active process of hypothesis testing, analogous to science, or whether realistic sensory information is rich enough to make this process unnecessary.
The perceptual systems of the brain enable individuals to see the world around them as stable, even though the sensory information is typically incomplete and rapidly varying. Human and other animal brains are structured in a Cognitive module, with different areas processing different kinds of sensory information. Some of these modules take the form of Sensory Maps, mapping some aspect of the world across part of the brain's surface. These different modules are interconnected and influence each other. For instance, taste is strongly influenced by smell.
To explain the process of perception, an example could be an ordinary shoe. The shoe itself is the distal stimulus. When light from the shoe enters a person's eye and stimulates the retina, that stimulation is the proximal stimulus. The image of the shoe reconstructed by the brain of the person is the percept. Another example could be a ringing telephone. The ringing of the phone is the distal stimulus. The sound stimulating a person's auditory receptors is the proximal stimulus. The brain's interpretation of this as the "ringing of a telephone" is the percept.
The different kinds of sensation (such as warmth, sound, and taste) are called sensory modalities or stimulus modalities.
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Ambiguous figures demonstrate that a single stimulus can result in more than one percept. For example, the Rubin vase can be interpreted either as a vase or as two faces. The percept can bind sensations from multiple senses into a whole. A picture of a talking person on a television screen, for example, is bound to the sound of speech from speakers to form a percept of a talking person.
The timing of perception of a visual event, at points along the visual circuit, have been measured. A sudden alteration of light at a spot in the environment first alters photoreceptor cells in the retina, which send a signal to the retina bipolar cell layer which, in turn, can activate a retinal ganglion neuron cell. A retinal ganglion cell is a bridging neuron that connects visual retinal input to the visual processing centers within the central nervous system. Light-altered neuron activation occurs within about 5–20 milliseconds in a rabbit retinal ganglion, although in a mouse retinal ganglion cell the initial spike takes between 40 and 240 milliseconds before the initial activation. The initial activation can be detected by an action potential spike, a sudden spike in neuron membrane electric voltage.
A perceptual visual event measured in humans was the presentation to individuals of an anomalous word. If these individuals are shown a sentence, presented as a sequence of single words on a computer screen, with a puzzling word out of place in the sequence, the perception of the puzzling word can register on an electroencephalogram (EEG). In an experiment, human readers wore an elastic cap with 64 embedded electrodes distributed over their scalp surface. Within 230 milliseconds of encountering the anomalous word, the human readers generated an event-related electrical potential alteration of their EEG at the left occipital-temporal channel, over the left occipital lobe and temporal lobe.
The auditory system includes the Ear, which collect and filter sound waves; the Ear, which transforms the sound pressure (impedance matching); and the Ear, which produces neural signals in response to the sound. By the ascending auditory pathway these are led to the primary auditory cortex within the temporal lobe of the human brain, from where the auditory information then goes to the cerebral cortex for further processing.
Sound does not usually come from a single source: in real situations, sounds from multiple sources and directions are as they arrive at the ears. Hearing involves the computationally complex task of separating out sources of interest, identifying them and often estimating their distance and direction.
Professor Gibson defined the haptic system as "the sensibility of the individual to the world adjacent to his body by use of his body." Gibson and others emphasized the close link between body movement and haptic perception, where the latter is active exploration.
The concept of haptic perception is related to the concept of extended physiological proprioception according to which, when using a tool such as a stick, perceptual experience is transparently transferred to the end of the tool.
Traditionally, there have been four primary tastes: sweetness, bitterness, sourness, and saltiness. The recognition and awareness of umami, which is considered the fifth primary taste, is a relatively recent development in Western cuisine. Other tastes can be mimicked by combining these basic tastes, all of which contribute only partially to the sensation and flavor of food in the mouth. Other factors include Odor, which is detected by the olfactory epithelium of the nose; texture, which is detected through a variety of , muscle nerves, etc.; Food texture: measurement and perception (page 3–4/311) Andrew J. Rosenthal. Springer, 1999. and temperature, which is detected by . All basic tastes are classified as either Reward system or Aversives, depending upon whether the things they sense are harmful or beneficial. Why do two great tastes sometimes not taste great together? scientificamerican.com. Dr. Tim Jacob, Cardiff University. 22 May 2009.
Smell is also a very interactive sense as scientists have begun to observe that olfaction comes into contact with the other sense in unexpected ways. It is also the most primal of the senses, as it is known to be the first indicator of safety or danger, therefore being the sense that drives the most basic of human survival skills. As such, it can be a catalyst for human behavior on a subconscious and level.
Listeners manage to perceive words across a wide range of conditions, as the sound of a word can vary widely according to words that surround it and the tempo of the speech, as well as the physical characteristics, accent, tone, and mood of the speaker. Reverberation, signifying the persistence of sound after the sound is produced, can also have a considerable impact on perception. Experiments have shown that people automatically compensate for this effect when hearing speech. (2010). 9781441956859, Springer. ISBN 9781441956859
The process of perceiving speech begins at the level of the sound within the auditory signal and the process of audition. The initial auditory signal is compared with visual information—primarily lip movement—to extract acoustic cues and phonetic information. It is possible other sensory modalities are integrated at this stage as well. This speech information can then be used for higher-level language processes, such as word recognition.
Speech perception is not necessarily uni-directional. Higher-level language processes connected with morphology, syntax, and/or semantics may also interact with basic speech perception processes to aid in recognition of speech sounds. It may be the case that it is not necessary (maybe not even possible) for a listener to recognize before recognizing higher units, such as words. In an experiment, professor Richard M. Warren replaced one phoneme of a word with a cough-like sound. His subjects restored the missing speech sound perceptually without any difficulty. Moreover, they were not able to accurately identify which phoneme had even been disturbed.
Affective is a type of sensory information that elicits an emotional reaction and is usually social in nature. Such information is actually coded differently than other sensory information. Though the intensity of affective touch is still encoded in the primary somatosensory cortex, the feeling of pleasantness associated with affective touch is activated more in the anterior cingulate cortex. Increased blood oxygen level-dependent (BOLD) contrast imaging, identified during functional magnetic resonance imaging (fMRI), shows that signals in the anterior cingulate cortex, as well as the prefrontal cortex, are highly correlated with pleasantness scores of affective touch. Inhibitory transcranial magnetic stimulation (TMS) of the primary somatosensory cortex inhibits the perception of affective touch intensity, but not affective touch pleasantness. Therefore, the S1 is not directly involved in processing socially affective touch pleasantness, but still plays a role in discriminating touch location and intensity.
One or more dopaminergic pathways in the central nervous system appear to have a strong modulatory influence on mental chronometry, particularly interval timing.
Even in non-Pathology cases, there is a measurable difference between the making of a decision and the feeling of agency. Through methods such as the Libet experiment, a gap of half a second or more can be detected from the time when there are detectable neurological signs of a decision having been made to the time when the subject actually becomes conscious of the decision.
There are also experiments in which an illusion of agency is induced in psychologically normal subjects. In 1999, psychologists Daniel Wegner and Wheatley gave subjects instructions to move a mouse around a scene and point to an image about once every thirty seconds. However, a second person—acting as a test subject but actually a confederate—had their hand on the mouse at the same time, and controlled some of the movement. Experimenters were able to arrange for subjects to perceive certain "forced stops" as if they were their own choice.
The temporal lobe (specifically the perirhinal cortex) responds differently to stimuli that feel novel compared to stimuli that feel familiar. Firing rates in the perirhinal cortex are connected with the sense of familiarity in humans and other mammals. In tests, stimulating this area at 10–15 Hz caused animals to treat even novel images as familiar, and stimulation at 30–40 Hz caused novel images to be partially treated as familiar. In particular, stimulation at 30–40 Hz led to animals looking at a familiar image for longer periods, as they would for an unfamiliar one, though it did not lead to the same exploration behavior normally associated with novelty.
Recent studies on in the area concluded that rats with a damaged perirhinal cortex were still more interested in exploring when novel objects were present, but seemed unable to tell novel objects from familiar ones—they examined both equally. Thus, other brain regions are involved with noticing unfamiliarity, while the perirhinal cortex is needed to associate the feeling with a specific source.
The confusing ambiguity of perception is exploited in human technologies such as camouflage and biological mimicry. For example, the wings of European peacock bear eyespots that birds respond to as though they were the eyes of a dangerous predator.
There is also evidence that the brain in some ways operates on a slight "delay" in order to allow nerve impulses from distant parts of the body to be integrated into simultaneous signals. The Secret Advantage Of Being Short by Robert Krulwich. All Things Considered, NPR. 18 May 2009.
Perception is one of the oldest fields in psychology. The oldest quantitative laws in psychology are Weber's law, which states that the smallest noticeable difference in stimulus intensity is proportional to the intensity of the reference; and Fechner's law, which quantifies the relationship between the intensity of the physical stimulus and its perceptual counterpart (e.g., testing how much darker a computer screen can get before the viewer actually notices). The study of perception gave rise to the Gestalt School of Psychology, with an emphasis on a Holism approach.
The receptive field is the specific part of the world to which a receptor organ and receptor cells respond. For instance, the part of the world an eye can see, is its receptive field; the light that each Rod cell or Cone cell can see, is its receptive field.Kolb & Whishaw: Fundamentals of Human Neuropsychology (2003) Receptive fields have been identified for the visual system, auditory system and somatosensory system, so far. Research attention is currently focused not only on external perception processes, but also to "interoception", considered as the process of receiving, accessing and appraising internal bodily signals. Maintaining desired physiological states is critical for an organism's well-being and survival. Interoception is an iterative process, requiring the interplay between perception of body states and awareness of these states to generate proper self-regulation. Afferent sensory signals continuously interact with higher order cognitive representations of goals, history, and environment, shaping emotional experience and motivating regulatory behavior.
Later research has identified additional grouping principles.
"Simultaneous contrast effect" is the term used when stimuli are presented at the same time, whereas successive contrast applies when stimuli are presented one after another.
The contrast effect was noted by the 17th Century philosopher John Locke, who observed that lukewarm water can feel hot or cold depending on whether the hand touching it was previously in hot or cold water. In the early 20th Century, Wilhelm Wundt identified contrast as a fundamental principle of perception, and since then the effect has been confirmed in many different areas. These effects shape not only visual qualities like color and brightness, but other kinds of perception, including how heavy an object feels. One experiment found that thinking of the name "Hitler" led to subjects rating a person as more hostile. Whether a piece of music is perceived as good or bad can depend on whether the music heard before it was pleasant or unpleasant. For the effect to work, the objects being compared need to be similar to each other: a television reporter can seem smaller when interviewing a tall basketball player, but not when standing next to a tall building. In the brain, brightness contrast exerts effects on both neuronal firing rates and neuronal synchrony.
The perceptual ecology approach was introduced by professor James J. Gibson, who rejected the assumption of a poverty of stimulus and the idea that perception is based upon sensations. Instead, Gibson investigated what information is actually presented to the perceptual systems. His theory "assumes the existence of stable, unbounded, and permanent stimulus-information in the ambient optic array. And it supposes that the visual system can explore and detect this information. The theory is information-based, not sensation-based."Gibson, James J. (2002): "
target="_blank" rel="nofollow"> A Theory of Direct Visual Perception". In: Alva Noë/Evan Thompson (Eds.), Vision and Mind. Selected Readings in the Philosophy of Perception, Cambridge, MIT Press, pp. 77–89. He and the psychologists who work within this paradigm detailed how the world could be specified to a mobile, exploring organism via the lawful projection of information about the world into energy arrays. "Specification" would be a 1:1 mapping of some aspect of the world into a perceptual array. Given such a mapping, no enrichment is required and perception is direct.
The constructivist view, held by such philosophers as Ernst von Glasersfeld, regards the continual adjustment of perception and action to the external input as precisely what constitutes the "entity," which is therefore far from being invariant.Consciousness in Action, S. L. Hurley, illustrated, Harvard University Press, 2002, 0674007964, pp. 430–432. Glasersfeld considers an invariant as a target to be homed in upon, and a pragmatic necessity to allow an initial measure of understanding to be established prior to the updating that a statement aims to achieve. The invariant does not, and need not, represent an actuality. Glasersfeld describes it as extremely unlikely that what is desired or feared by an organism will never suffer change as time goes on. This social constructionist theory thus allows for a needful evolutionary adjustment.Glasersfeld, Ernst von (1995), Radical Constructivism: A Way of Knowing and Learning, London: RoutledgeFalmer; Poerksen, Bernhard (ed.) (2004), The Certainty of Uncertainty: Dialogues Introducing Constructivism, Exeter: Imprint Academic; Wright. Edmond (2005). Narrative, Perception, Language, and Faith, Basingstoke: Palgrave Macmillan.
A mathematical theory of perception-in-action has been devised and investigated in many forms of controlled movement, and has been described in many different species of organism using the General Tau Theory. According to this theory, "tau information", or time-to-goal information is the fundamental percept in perception.
Building and maintaining sense organs is metabolically expensive. More than half the brain is devoted to processing sensory information, and the brain itself consumes roughly one-fourth of one's metabolic resources. Thus, such organs evolve only when they provide exceptional benefits to an organism's fitness.
Scientists who study perception and sensation have long understood the human senses as adaptations. Depth perception consists of processing over half a dozen visual cues, each of which is based on a regularity of the physical world. Vision evolved to respond to the narrow range of electromagnetic energy that is plentiful and that does not pass through objects. Sound waves provide useful information about the sources of and distances to objects, with larger animals making and hearing lower-frequency sounds and smaller animals making and hearing higher-frequency sounds. Taste and smell respond to chemicals in the environment that were significant for fitness in the environment of evolutionary adaptedness. The sense of touch is actually many senses, including pressure, heat, cold, tickle, and pain. Pain, while unpleasant, is adaptive. An important adaptation for senses is range shifting, by which the organism becomes temporarily more or less sensitive to sensation. For example, one's eyes automatically adjust to dim or bright ambient light. Sensory abilities of different organisms often co-evolve, as is the case with the hearing of echolocating bats and that of the moths that have evolved to respond to the sounds that the bats make.
Evolutionary psychologists claim that perception demonstrates the principle of modularity, with specialized mechanisms handling particular perception tasks. For example, people with damage to a particular part of the brain are not able to recognize faces ( prosopagnosia). Evolutionary psychology suggests that this indicates a so-called face-reading module.
The preattentive stage of perception is largely unconscious, and analyzes an object by breaking it down into its basic features, such as the specific color, geometric shape, motion, depth, individual lines, and many others. Studies have shown that, when small groups of objects with different features (e.g., red triangle, blue circle) are briefly flashed in front of human participants, many individuals later report seeing shapes made up of the combined features of two different stimuli, thereby referred to as illusory conjunctions.
The unconnected features described in the preattentive stage are combined into the objects one normally sees during the focused attention stage. The focused attention stage is based heavily around the idea of attention in perception and 'binds' the features together onto specific objects at specific spatial locations (see the binding problem).
/ref>McClung, J. S., Placì, S., Bangerter, A., Clément, F., & Bshary, R. (2017). "The language of cooperation: shared intentionality drives variation in helping as a function of group membership." Proceedings of the Royal Society B: Biological Sciences, 284(1863), 20171682. http://dx.doi.org/10.1098/rspb.2017.1682.Shteynberg, G., & Galinsky, A. D. (2011). "Implicit coordination: Sharing goals with similar others intensifies goal pursuit." Journal of Experimental Social Psychology, 47(6), 1291-1294., https://doi.org/10.1016/j.jesp.
2011.04.012. and neurobiology.Fishburn, F. A., Murty, V. P., Hlutkowsky, C. O., MacGillivray, C. E., Bemis, L. M., Murphy, M. E., ... & Perlman, S. B. (2018). "Putting our heads together: interpersonal neural synchronization as a biological mechanism for shared intentionality." Social cognitive and affective neuroscience, 13(8), 841-849. The Shared intentionality approach considers perception occurrence at an earlier stage of organisms' development than other theories, even before the emergence of Intentionality. Because many theories build their knowledge about perception based on its main features of the organization, identification, and interpretation of sensory information to represent the holistic picture of the environment, Intentionality is the central issue in perception development. Nowadays, only one hypothesis attempts to explain Shared intentionality in all its integral complexity from the level of interpersonal dynamics to interaction at the neuronal level. Introduced by Latvian professor Igor Val Danilov, the hypothesis of neurobiological processes occurring during Shared intentionality highlights that, at the beginning of cognition, very young organisms cannot distinguish relevant sensory stimuli independently. Because the environment is the cacophony of stimuli (electromagnetic waves, chemical interactions, and pressure fluctuations), their sensation is too limited by the noise to solve the cue problem. The relevant stimulus cannot overcome the noise magnitude if it passes through the senses. Therefore, Intentionality is a difficult problem for them since it needs the representation of the environment already categorized into objects (see also binding problem). The perception of objects is also problematic since it cannot appear without Intentionality. From the perspective of this hypothesis, Shared intentionality is collaborative interactions in which participants share the essential sensory stimulus of the actual cognitive problem. This social bond enables ecological training of the young immature organism, starting at the reflexes stage of development, for processing the organization, identification, and interpretation of sensory information in developing perception. From this account perception emerges due to Shared intentionality in the embryonic stage of development, i.e., even before birth.
Past actions and events that transpire right before an encounter or any form of stimulation have a strong degree of influence on how sensory stimuli are processed and perceived. On a basic level, the information our senses receive is often ambiguous and incomplete. However, they are grouped together in order for us to be able to understand the physical world around us. But it is these various forms of stimulation, combined with our previous knowledge and experience that allows us to create our overall perception. For example, when engaging in conversation, we attempt to understand their message and words by not only paying attention to what we hear through our ears but also from the previous shapes we have seen our mouths make. Another example would be if we had a similar topic come up in another conversation, we would use our previous knowledge to guess the direction the conversation is headed in.
Sets can be created by motivation and so can result in people interpreting ambiguous figures so that they see what they want to see. For instance, how someone perceives what unfolds during a sports game can be biased if they strongly support one of the teams. In one experiment, students were allocated to pleasant or unpleasant tasks by a computer. They were told that either a number or a letter would flash on the screen to say whether they were going to taste an orange juice drink or an unpleasant-tasting health drink. In fact, an ambiguous figure was flashed on screen, which could either be read as the letter B or the number 13. When the letters were associated with the pleasant task, subjects were more likely to perceive a letter B, and when letters were associated with the unpleasant task they tended to perceive a number 13.
Perceptual set has been demonstrated in many social contexts. When someone has a reputation for being funny, an audience is more likely to find them amusing. Individual's perceptual sets reflect their own personality traits. For example, people with an aggressive personality are quicker to correctly identify aggressive words or situations. In general, perceptual speed as a mental ability is positively correlated with personality traits such as conscientiousness, emotional stability, and agreeableness suggesting its evolutionary role in preserving homeostasis.
One classic psychological experiment showed slower reaction times and less accurate answers when a deck of playing cards reversed the color of the suit symbol for some cards (e.g. red spades and black hearts)."On the Perception of Incongruity: A Paradigm" by Jerome S. Bruner and Leo Postman. Journal of Personality, 18, pp. 206-223. 1949. Yorku.ca
Philosopher Andy Clark explains that perception, although it occurs quickly, is not simply a bottom-up process (where minute details are put together to form larger wholes). Instead, our brains use what he calls predictive coding. It starts with very broad constraints and expectations for the state of the world, and as expectations are met, it makes more detailed predictions (errors lead to new predictions, or learning processes). Clark says this research has various implications; not only can there be no completely "unbiased, unfiltered" perception, but this means that there is a great deal of feedback between perception and expectation (perceptual experiences often shape our beliefs, but those perceptions were based on existing beliefs). Indeed, predictive coding provides an account where this type of feedback assists in stabilizing our inference-making process about the physical world, such as with perceptual constancy examples.
Embodied cognition challenges the idea of perception as internal representations resulting from a passive reception of (incomplete) sensory inputs coming from the outside world. According to O'Regan (1992), the major issue with this perspective is that it leaves the subjective character of perception unexplained. Thus, perception is understood as an active process conducted by perceiving and engaged agents (perceivers). Furthermore, perception is influenced by agents' motives and expectations, their bodily states, and the interaction between the agent's body and the environment around it.
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