Perception: Difference between revisions

|Authors=[[User:Maja Elena B. Schachtner|Maja Schachtner]]

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Perception is the sensory experience of the world <ref name="ref1"/>, the process and the subjective result of obtaining and processing information from stimuli originated in the environment and the self. An object or situation may be perceived differently by multiple individuals. Everyone is limited to their own perception. Perception is shaped through internal and external factors, such as ones beliefs, knowledge, experiences and sensing structures. Personal circumstances can also affect one's perception. What we perceive is not an accurate depiction of the externally existing world. One's perception of reality is one's brains perception. Personal stories reflective of master narratives you were born into hailed by ideology <ref name="ref2"/> may also take effect.

Perception entails our diverse modalities of vision, touch, hearing, taste, and smell into an experience of the external world. Yet this experience is far from a direct reflection of reality. Individual perception is filtered by biological mechanisms, personal beliefs, and cultural contexts. As neuroscientific research shows, external stimuli are transformed into meaningful patterns. For this reason, philosophical approaches question how these patterns relate to any objective reality. Furthermore, we highlight the inherent subjectivity of perception by acknowledging that personal factors ranging from emotional states to social narratives shape the way we interpret stimuli. Consequently, examining both the neuroscience of sensation and the philosophical implications of our  perceptual construction of the world, it broadens our understanding of implicit and explicit frameworks of reality.

Visual perception can be understood as a diverse process that begins with the transformation of light stimuli into meaningful cognitive interpretations involving retinal sensing through photoreceptors and cortical processing in multiple brain areas.<ref name=":0">Donato, R., Pavan, A., & Campana, G. (2020). Investigating the Interaction Between Form and Motion Processing: A Review of Basic Research and Clinical Evidence. ''Frontiers in Psychology'', ''11''. <nowiki>https://doi.org/10.3389/fpsyg.2020.566848</nowiki></ref> The photoreceptors receive light signals through the retina, converting them into electrical signals. Those signals are then transmitted along the optic nerve in the eye, in order to reach the lateral geniculate nucleus before arriving at the striate cortex. This cortex, known as the visual cortex serves on fundamental basis for the conscious perception of static form and local brightness differences, establishing the base for more complex visual processing.<ref>Pollen, D. A. (1999). On the Neural Correlates of Visual Perception. ''Cerebral Cortex'', ''9''(1), 4–19. <nowiki>https://doi.org/10.1093/cercor/9.1.4</nowiki></ref> Following that, after leaving the visual cortex, signals travel along the dorsal stream to the parietal cortex, serving for spatial orientation and motor actions such as reaching or eye movements. Further, focusing on forms, colours and object identity, signals must flow through the ventral stream into the inferior temporal cortex.<ref name=":0" /> For perceptual experience to be created, the visual cortex engages in recursive feedback loops with higher brain regions, for instance temporal and parietal. Those feedbacks enter into loops between each other to continuously compare new sensory data with prior knowledge or expectations, leading to our visual recognition of the outer world.<ref name=":0" /> Visual perception involves actively searching for relevant stimuli, influenced by external factors such as color salience and movement, as well as internal states in order to recognise objects. For instance, conspicuous features can capture human attention instantly, leading to unusual preferences when distractions occur. At this state, the ventral stream captures specific details from it. In addition, the temporal cortex stores those representations, helping humans to categorise and label familiar objects in fractions of a second. <ref name=":1">Jansson-Boyd, C. V., & Bright, P. (2024). Visual neuroscience. ''Elsevier EBooks'', 51–69. <nowiki>https://doi.org/10.1016/b978-0-443-13581-1.00004-2</nowiki></ref> Furthermore, visual search engages emotional and reward circuits, when identifying form and motion. The ventral tegmental area and nucleus accumbens interact with cortical regions to process rewarding stimuli, reinforcing behaviour patterns triggered by appealing elements. Likewise research shows, that emotional associations are carried firmly throughout visual perception, that bias us towards or against objects before consciously registering the object. This phenomenon, known as microvalence, refers to subconscious evaluation of an object's aversiveness during visual processing.<ref name=":1" />

Touch helps us to navigate through the physical space, by integrating information from the skin, muscles and joints to foster a cohesive perception of objects, surfaces and spatial relationships. While joints and muscles enables feedback about cup's orientation and weight, the skin contains a complex system of specialised nerve endings designed to detect mechanical stimuli such as pressure, vibration, and texture. <ref name=":02">Reed, Catherine L., and Mounia Ziat. “Haptic Perception: From the Skin to the Brain ☆.” ''Reference Module in Neuroscience and Biobehavioral Psychology'', 2018, <nowiki>https://doi.org/10.1016/b978-0-12-809324-5.03182-5</nowiki>.</ref> The majority of receptors, which are distributed throughout the layers of the skin, are represented by:

Therefore, the multiple lines of sensory information offer a detailed and adaptive representation of the physical world.<ref name=":02" />

The interpretation of sound, begins with sound waves defined as vibration through a medium, for instance air pressure, which travales through the outer ear channels towards the eardrum. The eardrums begin to vibrate and convey them through the middle ear bones into the fluid-filled cochlea of the inner ear. Further, the frequency being established in the basilar membrane of the cochlea disperse it to specific locations, forming a tonotopic map. Hair cells convert these mechanical vibrations into neural signals transmitted onwards the auditory nerve to the brain. However, due to fine arranged cochlear filters a vast range of sound frequencies can be detected and separated into distinct pitches.<ref name=":2">Oxenham, Andrew J. “How We Hear: The Perception and Neural Coding of Sound.” ''Annual Review of Psychology'', vol. 69, no. 1, 4 Jan. 2018, pp. 27–50, www.ncbi.nlm.nih.gov/pmc/articles/PMC5819010/, <nowiki>https://doi.org/10.1146/annurev-psych-122216-011635</nowiki>.</ref> Once the signals travel through the central auditory nerve, main sound properties such as amplitude and frequency are processed by the midbrain's inferior colliculus, while high frequency is received by the inferior colliculus, overlapping with pure auditory processing. However, before tactile high frequencies reach the inferior colliculus, they must pass through the pacinian corpuscles of the skin. Pacinian corpuscles are primarily touch receptors contributing to a better sound experience. This overall convergence suggests, that touch and sound information being shared thereby interchangeable neuronal circuits, being the reason therefore why we feel and hear music. This underlines the human capacity to distinguish numerous pitches due to the cochlea's ability to segregate frequencies precisely.<ref name=":2" />

Generally speaking, perceiving smell begins in the nose, where specialised olfactory receptors bind molecules. Correspondingly, humans posses approximately 396 functional receptor genes and many pseudogenes. These genes encode a large family of proteins found on the surface of cells. As a result of encoding these G protein-coupled receptors, cells can respond to thousands of potential molecules entering our nasal cavity. This binding creates an electrical signal to the transmitted to the olfactory bulb, where subtle scent differences are distinguished.<ref>Sharma, Anju, et al. “Sense of Smell: Structural, Functional, Mechanistic Advancements and Challenges in Human Olfactory Research.” ''Current Neuropharmacology'', vol. 17, no. 9, 22 Aug. 2019, pp. 891–911, www.ncbi.nlm.nih.gov/pmc/articles/PMC7052838/, <nowiki>https://doi.org/10.2174/1570159x17666181206095626</nowiki>.</ref> After initial processing in the olfactory bulb, those information are passed to the piriform cortex region, where odor identification occurs, while on the other hand the amygdala and hippocampus receive likewise signals. The amygdala and hippocampus link smells to emotions and memories, contributing additional to an experience of recollections.<ref>NeuroLaunch editorial team. “Brain and Smell: Exploring the Olfactory System’s Neural Pathways.” ''NeuroLaunch.com'', 30 Sept. 2024, neurolaunch.com/what-part-of-the-brain-controls-smell/.</ref> Moreover, research suggest that the right orbitofrontal cortex (OFC) is essential for consicous olfactory awareness. As depicted in a case, individuals with damage to the right OFC can partially response to smell, while being unaware of it. Even though, odor processing occurs at the piriform cortex or left OFC, a full smell perception requires the connectivity of all involved brain regions.<ref>Li, Wen, et al. “Right Orbitofrontal Cortex Mediates Conscious Olfactory Perception.” ''Psychological Science'', vol. 21, no. 10, 3 Sept. 2010, pp. 1454–1463, <nowiki>https://doi.org/10.1177/0956797610382121</nowiki>.</ref> Nevertheless, the interplay between smell, memory and emotion is profound, hence it can evoke memories and shape our affective mood.

The idea of taste starts with taste visual buds found in across the tongue's surface - called papillae, where each bud contains receptor cells, supporting cells, and basal cells. <ref>Henley, Casey. “Taste.” ''Openbooks.lib.msu.edu'', Michigan State University Libraries, 1 Jan. 2021, openbooks.lib.msu.edu/neuroscience/chapter/taste/.</ref> Flavour such as sugars or bitter alkaloids are detected by those cells and converted into electrical signals. The signals are then transmitted via the cranial nerves to the brainstem and thalamus before reaching the primary gustatory cortex, where flavour information is perceived and processed.<ref>team, NeuroLaunch editorial. “Brain’s Taste Control Center: Mapping the Neural Pathways of Flavor Perception.” ''NeuroLaunch.com'', 30 Sept. 2024, neurolaunch.com/what-part-of-the-brain-controls-taste/. Accessed 29 Dec. 2024.</ref> Besides the gustatory cortex, taste, smell, and texture are  as well processed by the orbitofrontal cortex, influencing decisions about consume behaviour. In comparison, certain tastes evoke memories being attributable to the amygdala, while the hypothalamus contributes by regulating appetite and taste preferences. However, flavour depends, as a research depicts, further from genetics, aging, and neurological conditions. This underlies that the function of taste involves numerous neural circuits ensuring that each bite resonates beyond the tongue.<ref>Trivedi, Bijal P. “Neuroscience: Hardwired for Taste.” ''Nature'', vol. 486, no. 7403, June 2012, pp. S7–S9, <nowiki>https://doi.org/10.1038/486s7a</nowiki>.</ref>

Dualism proposes that perceiving is not an one dimensional outcome of physical processes in the brain, rather it involves a separate mental dimension which shapes our conscious experience. Accordingly the idea of Descartes argues that the mind is indeed a thinking substance distinct from the body's extended substance. While eyes, ears, and other organs receive physical data, our conscious perception exceeds these signals, and being therefore accountable for our intentional and subjective interpretation within our mental realm. For this reason, the dualism claims that physical explanations cannot resolve the pure nature of sensory experience. For instance, when viewing a striking painting, the sensation is tangled to the subjective awareness in a way, where no objective, third-person description of the painting's properties could evoke the same experience. Therefore, if mental events were only based on physical circumstances, then anyone using the right instruments could equally observe, yet first-person experiences resist sich observations. Nonetheless, whether the mental district is a separated substance or not, dualism demands that understanding true perception requires more than physical causation alone. <ref>Robinson, Howard. “Dualism.” ''Stanford Encyclopedia of Philosophy'', 2020, plato.stanford.edu/entries/dualism/.</ref>

Direct realism suggests that the perception of objects such as chairs, sun, or cups of coffee, arises from our engagement with them, rather than mere mental images. A sensible idea for this implies that objects exist independently of any perceiver's awareness. Hence, direct realism can be divided into naïve realism and scientific realism. According to naïve realism, objects retain all perceived properties, for example colour or surface texture regardless of the observation. In contrast, scientific realism argues that certain examined qualities (e.g., sweetness) depend on the examiner, while mass or shape persist irrespective of observation. Likewise, Locke's notion of primary (e.g, size, motion) versus secondary (e.g., colour, taste) qualities aligns partially, whereas primary exists objectively and secondary dispositional. However, both assert fundamentally that the senses must be in direct contact with the external reality. <ref name=":4">O’Brien, Daniel. “Perception, Objects of | Internet Encyclopedia of Philosophy.” ''Objects of Perception'', iep.utm.edu/perc-obj/#H1.</ref>

Indirect realism states that physical objects exist mind-independently, and we therefore perceive them through an internal intermediary rather than directly. This construct (intermediary), acts as a bridge between the mind and the external world. For instance, a chair is an internally produced image in the human visual system caused by the physical properties (light reflection, etc.), rather than a physcial entity itself.<ref name=":4" /> Hence, these physical objects and their properties cause mental perceptions, being commonly termed with sense data (e.g., colour, texture, shape). Despite being caused by physical stimuli, these sensed data are not themselves physical. According to John Locke, we do not perceive an external object itself but rather our idea of it, reinforcing this idea of an intermediary.<ref name="ref14" /> <ref name="ref13" /> Thus, the mind indirectly perceives an object thorugh sense data, which is generated in part by a causal chain including light rays, neuronal processes, and the subjective experience of colour, shape, or other features.<ref name=":4" /> As a result, the real object (e.g., a chair) remains independent of the observer, while our knowledge of the external world exists constantly indirect.

Internal Perception depicts about the internal world of a being, the world within the body. Feelings and information about ones body (e.g. positions, organic functions) falls into this category.  

External Perception describes the world outside of the body. Therefore we use our senses such as hearing, smelling and touching to perceive the external world.

Ones current emotional state often has a strong impact on their perception. Feelings and emotions may arise for multiple reasons. Be it an interaction, reaction, an experience or a hormonal setting.

The endocrine system regulates everything exerting its influence over the cells. It relies on interactions between glands, hormones and cell receptors. In order to manage balance within the body.

Mood hormones can influence the production of certain chemicals in the brain, like serotonin. When chemical levels shift, they also cause changes in mood. Humans behaviors are collectively shaped by a variety of influences, the brain and its neurotransmitters, hormones and various social factors <ref name="ref11" />.Therefore hormones hugely affect ones emotions, for example serotonin as the happiness hormone and progesterone for calming.

The human being has the ability to focus his perception. If one is in danger, for example, and a lot of adrenaline is released, his perception of external influences is documented. Therefore his perception focuses on hearing, seeing and smelling. Other perceptions, especially in the area of the emotional level, are largely faded out with the exception of the fearful feeling in a panic situation. Through the adrenaline rush, even the sense of pain may be temporarily eliminated. This is a result of the humans survival instincts.

The same goes for other focus situations. When focused while working on a piece of work, external perceptions, such as hearing and smelling are faded out. And when asleep, emotional impressions and experiences in particular are processed, possibly resulting in certain events in ones dreams.

The process of making judgments about other people is called social perception. During the first impression this process happen already, the so-called primacy effect. Later, this judgment can harden further through so-called summation and implicit personality theories.

This subfield has a special place in scientific psychology and social research, because social perception or judgment determines how one views, turns toward, or rejects other people.<ref name="ref12" />

# Stimulation

# Organization

# (Recall)

Human perception is limited by the limited capacity of human receptors. For example, the eyes can only absorb a very limited frequency range of light. In contrast to some animals, hearing is also limited (e.g.: bats, ultrasonic range). This limitation affects not only the perception but also the ability to react in various external situations. In addition to the limitations of hearing and seeing, the limitation of human perception has further limitations. For example the perception of the skin in this area is also very limited. A shark can perceive the minimalist movement of a fish via its lateral sensory organs, which are transmitted through water. The sense of smell animals such as sharks regarding blood or of some insects in the area of the perception of pheromones already shows a perception in the molecular area. The sense of smell is tightly networked with the sense of smell. In this category of perception, too, humans are inferior to many animals. In comparison to some animal species, humans cannot perceive electromagnetic fields. These examples show the limitations of the human perception. The limitation of man culminates in the limitation of his ability to think. This can be seen for example, in the limited ability to think, since when looking for solutions to problems one usually turns in a circle that is difficult to get out of. It is assumed that computers will reach performance of our brains by 2030 (the performance of a computer will double every 1-2 years)<ref name="ref10"/>. Through all these limitations, the human being is determined within its „self“ and „being“.

According to Saks and Johns, perception is categorized into three components of perception, The Perceiver, The Target and The Situation.

The Perceiver is influenced by external and internal factors, which affect the perceivers perception of the target.

The Situation and it's context can heavily impact the perception. "The most important effect that the situation can have is to add information about the target"<ref name="ref16" /><ref name="ref17" />.

==Philosophical Views==