Perception

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 or cone can see, is its receptive field.^[57] 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.^[58]

Features

Constancy

Perceptual constancy is the ability of perceptual systems to recognize the same object from widely varying sensory inputs.^{[5]: 118–120 [59]} For example, individual people can be recognized from views, such as frontal and profile, which form very different shapes on the retina. A coin looked at face-on makes a circular image on the retina, but when held at angle it makes an elliptical image.^[21] In normal perception these are recognized as a single three-dimensional object. Without this correction process, an animal approaching from the distance would appear to gain in size.^[60][61] One kind of perceptual constancy is color constancy: for example, a white piece of paper can be recognized as such under different colors and intensities of light.^[61] Another example is roughness constancy: when a hand is drawn quickly across a surface, the touch nerves are stimulated more intensely. The brain compensates for this, so the speed of contact does not affect the perceived roughness.^[61] Other constancies include melody, odor, brightness and words.^[62] These constancies are not always total, but the variation in the percept is much less than the variation in the physical stimulus.^[61] The perceptual systems of the brain achieve perceptual constancy in a variety of ways, each specialized for the kind of information being processed,^[63] with phonemic restoration as a notable example from hearing.

Grouping (Gestalt)

The principles of grouping (or Gestalt laws of grouping) are a set of principles in

1. Proximity: the principle of proximity states that, all else being equal, perception tends to group stimuli that are close together as part of the same object, and stimuli that are far apart as two separate objects.
2. Similarity: the principle of similarity states that, all else being equal, perception lends itself to seeing stimuli that physically resemble each other as part of the same object and that are different as part of a separate object. This allows for people to distinguish between adjacent and overlapping objects based on their visual texture and resemblance.
3. Closure: the principle of closure refers to the mind's tendency to see complete figures or forms even if a picture is incomplete, partially hidden by other objects, or if part of the information needed to make a complete picture in our minds is missing. For example, if part of a shape's border is missing people still tend to see the shape as completely enclosed by the border and ignore the gaps.
4. Good Continuation: the principle of good continuation makes sense of stimuli that overlap: when there is an intersection between two or more objects, people tend to perceive each as a single uninterrupted object.
5. Common Fate: the principle of common fate groups stimuli together on the basis of their movement. When visual elements are seen moving in the same direction at the same rate, perception associates the movement as part of the same stimulus. This allows people to make out moving objects even when other details, such as color or outline, are obscured.
6. The principle of good form refers to the tendency to group together forms of similar shape, pattern, color, etc.^{[64][65][66][67]}

Later research has identified additional grouping principles.^[68]

Contrast effects

A common finding across many different kinds of perception is that the perceived qualities of an object can be affected by the qualities of context. If one object is extreme on some dimension, then neighboring objects are perceived as further away from that extreme.

"

Cognitive theories of perception assume there is a poverty of stimulus. This is the claim that sensations, by themselves, are unable to provide a unique description of the world.^[75] Sensations require 'enriching', which is the role of the mental model.

The

Many philosophers, such as Jerry Fodor, write that the purpose of perception is knowledge. However, evolutionary psychologists hold that the primary purpose of perception is to guide action.^[81] They give the example of depth perception, which seems to have evolved not to aid in knowing the distances to other objects but rather to aid movement.^[81] Evolutionary psychologists argue that animals ranging from fiddler crabs to humans use eyesight for collision avoidance, suggesting that vision is basically for directing action, not providing knowledge.^[81] Neuropsychologists showed that perception systems evolved along the specifics of animals' activities. This explains why bats and worms can perceive different frequency of auditory and visual systems than, for example, humans.

Building and maintaining sense organs is

Scientists who study perception and sensation have long understood the human senses as adaptations.[81] Depth perception consists of processing over half a dozen visual cues, each of which is based on a regularity of the physical world.^[81] Vision evolved to respond to the narrow range of electromagnetic energy that is plentiful and that does not pass through objects.^[81] 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.^[81] Taste and smell respond to chemicals in the environment that were significant for fitness in the environment of evolutionary adaptedness.^[81] The sense of touch is actually many senses, including pressure, heat, cold, tickle, and pain.^[81] Pain, while unpleasant, is adaptive.^[81] An important adaptation for senses is range shifting, by which the organism becomes temporarily more or less sensitive to sensation.^[81] For example, one's eyes automatically adjust to dim or bright ambient light.^[81] 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.^[81]

Evolutionary psychologists claim that perception demonstrates the principle of modularity, with specialized mechanisms handling particular perception tasks.^[81] For example, people with damage to a particular part of the brain are not able to recognize faces (prosopagnosia).^[81] Evolutionary psychology suggests that this indicates a so-called face-reading module.^[81]

Closed-loop perception

The theory of closed-loop perception proposes dynamic motor-sensory closed-loop process in which information flows through the environment and the brain in continuous loops.^{[82][83][84][85]} Closed-loop perception appears consistent with anatomy and with the fact that perception is typically an incremental process. Repeated encounters with an object, whether conscious or not, enable an animal to refine its impressions of that object. This can be achieved more easily with a circular closed-loop system than with a linear open-loop one. Closed-loop perception can explain many of the phenomena that open-loop perception struggles to account for. This is largely because closed-loop perception considers motion to be an integral part of perception, and not an interfering component that must be corrected for. Furthermore, an environment perceived via sensor motion, and not despite sensor motion, need not be further stabilized by internal processes.^[85]

Feature integration theory

Anne Treisman's feature integration theory (FIT) attempts to explain how characteristics of a stimulus such as physical location in space, motion, color, and shape are merged to form one percept despite each of these characteristics activating separate areas of the cortex. FIT explains this through a two part system of perception involving the preattentive and focused attention stages.^{[86][87][88][89][90]}

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.^[86] 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.^[86][89]

The unconnected features described in the preattentive stage are combined into the objects one normally sees during the focused attention stage.^[86] 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).^[86][90]

Shared Intentionality theory

A fundamentally different approach to understanding the perception of objects relies upon the essential role of Shared intentionality.^[91] Cognitive psychologist professor Michael Tomasello hypothesized that social bonds between children and caregivers would gradually increase through the essential motive force of shared intentionality beginning from birth.^[92] The notion of shared intentionality, introduced by Michael Tomasello, was developed by later researchers, who tended to explain this collaborative interaction from different perspectives, e.g., psychophysiology,^[93][94][95] and neurobiology.^[96] 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^[97] 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.^[98] From this account perception emerges due to Shared intentionality in the embryonic stage of development, i.e., even before birth.^[99]

Other theories of perception

• Enactivism
• The Interactive Activation and Competition Model
• Recognition-By-Components Theory (Irving Biederman)

Effects on perception

Effect of experience