Perception

[gL.edu] This article gathers contributions by Maja Schachtner, Haris Omerhodzic, developed within the context of the Conceptual clarification about "Information, Knowledge and Philosophy", under the supervisión of J.M. Díaz Nafría.

Perception is the sensory experience of the world , the process, and the subjective result of obtaining and processing information from stimuli originated in the environment and the self. Yet every individual may perceive the same situation differently, which is filtered by biological mechanisms, personal beliefs, and cultural contexts. What we perceive may be far from a direct reflection of reality. Personal interpretation is further influenced by cultural or ideological circumstances, affecting individual worldviews consistently. Whether through vision, touch, hearing, taste, or smell, human perception is never purely objective. For this reason, philosophical approaches question how each person's subjective pattern recognition relates to any objective reality. Consequently, examining both the neuroscience of sensation and the philosophical implications of our perceptual construction of the world broadens our understanding of implicit and explicit frameworks of reality.

Neuroscientific Foundations

Visual Perception

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. 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 as a fundamental basis for the conscious perception of static form and local brightness differences, establishing the base for more complex visual processing. 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. For perceptual experience to arise, 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. Along with Descartes analytical approach, raw light signals are simplified into features such as edges and movements by the visual cortex, then recombined under the guidance of attention and memory. This creates a synergy between modern neuroscience and analysing complex phenomena into smaller bits.

Moreover, visual perception involves actively searching for relevant stimuli, influenced by external factors such as colour 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. In addition, the temporal cortex stores those representations, helping humans to categorise and label familiar objects in fractions of a second. 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, which biases us towards or against objects before we consciously register the object. This phenomenon, known as microvalence, refers to subconscious evaluation of an object's aversiveness during visual processing.

Haptic Perception

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 enable feedback about an object'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. The majority of receptors, which are distributed throughout the layers of the skin, are represented by:

1. Merkel's Disc's:
   • Located in the deep epidermis
   • Highly sensitive to light touch and fine details
2. Hair Follicle Receptors:
   • Responding to bending or subtle movement of hair
   • Detection of gentle stimuli (e.g., a soft breeze)
3. Mechanoreceptors:
   • Meissner's Corpuscles: Specialise in detecting fine, precise touch and are concentrated in the fingertips
   • Pacinian Corpuscles: Respond to deep pressure and vibration regarding sudden changes in pressure
   • Ruffini's Endings: Perceives sustained pressure and skin stretch, helping to maintain a firm grip on objects

At different rates of stimulation, each of the receptor types adapts continuously. Likewise, it converts physical energy (pressure, vibration, temperature) into electrical impulses, which are sent along nerve fibres towards the spinal cord, ensuring instantaneous awareness of haptic changes. The electrical impulses are either transmitted through slowly adapting fibres, firing with persistent pressure, or rapidly adapting fibers. Once triggered, these signals travel to the somatosensory cortex, containing topographic maps of the skin, which represent different body parts. Furthermore, heating or cooling are detected by skin thermoreceptors influencing our recognition of objects (e.g., metal feels colder than plastic at room temperature). If an object begins to warm up or cool down in the hand, through feedback humans can then indicate material properties such as moisture. This overall process from touching to interpretation follows multiple pathways. First of all, the skin collects input with receptors (touch and vibration). Further, it leads to an awareness of the object's movement in order to judge its weight and orientation, which is defined as kinaesthetic feedback. This refers to the sense of limb movement, where muscles, tendons, and joints work together with inputs to inform the brain. Those information are then processed at the cortex and other parietal regions. Consequently, the multiple lines of sensory information offer a detailed and adaptive representation of the physical world.

Auditory Perception

The interpretation of sound begins with sound waves defined as vibrations through a medium, for instance, air pressure, which travels 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 disperses 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 finely arranged cochlear filters, a vast range of sound frequencies can be detected and separated into distinct pitches. 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. In the same way, hearing a sound from different angles illustrates how inductive reasoning shapes the confidence we have in locating a pitch, leading to an overcross of auditory sensation and perceptual belief.

Smell Perception

Generally speaking, perceiving smell begins in the nose, where specialised olfactory receptors bind molecules. Correspondingly, humans possess 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 that is transmitted to the olfactory bulb, where subtle scent differences are distinguished.

After initial processing in the olfactory bulb, that information is passed to the piriform cortex region, where odour identification occurs, while on the other hand the amygdala and hippocampus receive similar signals. The amygdala and hippocampus link smells to emotions and memories, contributing additionally to an experience of recollections.

Moreover, research suggests that the right orbitofrontal cortex (OFC) is essential for conscious olfactory awareness. As depicted in a case, individuals with damage to the right OFC can partially respond to smell while being unaware of it. Even though odour processing occurs at the piriform cortex or left OFC, a full smell perception requires the connectivity of all involved brain regions. Nevertheless, the interplay between smell, memory, and emotion is profound, hence it can evoke memories and shape our affective mood.

Taste Perception

The idea of taste starts with taste visual buds found across the tongue's surface—called papillae, where each bud contains receptor cells, supporting cells, and basal cells. Flavours 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.

Besides the gustatory cortex, taste, smell, and texture are also processed by the orbitofrontal cortex, influencing decisions about consumption 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 research depicts, further from genetics, ageing, and neurological conditions. This underlies that the function of taste involves numerous neural circuits ensuring that each bite resonates beyond the tongue.

Philosophical Dimensions

Dualism

Dualism proposes that perceiving is not a one-dimensional outcome of physical processes in the brain, rather, it involves a separate mental dimension that 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. This aligns with Plato's views, where the soul is held to be immaterial and intellectually with higher being forms. While eyes, ears, and other organs receive physical data, our conscious perception exceeds these signals, and we are 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 such observations. Nonetheless, whether the mental district is a separated substance or not, dualism demands that understanding true perception requires more than physical causation alone.

The Causal Theory

Perception requires a causal link between an external object and the perceiver's sensory experience following the causal theory. We see, hear, or smell an object if that object itself brings the relevant sensory experiences. This principle can be illustrated by the thought experiment where a blocked pathway (e.g., a mirror) exists in front of the person and the pillar behind the person, no direct causal relationship exists, and therefore the pillar cannot be truly perceived. In this scenario, the mirror redirects the light from the actual pillar to the eyes, and therefore the individual cannot perceive the intended object. Likewise suggested by Hyman, a person lacks true perception if the external object is not causing the experience. This applies across modalities of vision, auditory, and olfaction for intuitive judgement in "Blocker cases" (e.g., a mirror redirecting) and "Non-Blocker cases" (e.g., brain stimulation producing similar experience). However, some individuals diverge from those intuitive philosophical standpoints, where participants believe that genuine perception can occur even in non-Blocker scenarios, as shown by studies. This discrepancy raises questions about whether causal condition is truly a conceptual truth for perception. Thereupon, this mismatch illustrates that individuals assume perception might be conceivable only on brain stimulation, implying an exposure without physical obstruction.

In contrast, due to the causal condition embedded in our very own concept of perception, deeper reflection or strict philosophical training is needed to align our intuitions with the standards of the causal theory. Nonetheless, in order to avoid illusions or blocked pathways, it is necessary to identify if the external cause matches the internal impression.

Direct Realism

Direct realism suggests that the perception of objects such as chairs, books, 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.

Indirect Realism

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 physical entity itself. 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. Thus, the mind indirectly perceives an object through 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. 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.

The Intentional Theory

Perception is a representational relationship linking conscious experience to the external world in virtue of their content rather than any direct sensory object following the intentional theory. However, we perceive a chair not by apprehending a mental entity, but by adopting a perceptual state that possess intentional content. This suggests that our perceptual state inherently carries representations (e.g., there is a chair) that manifest the existence of objects within our mind. Therefore, seeing a bent stick in water is experienced still as a bent stick despite the fact that the stick might be straight in the physical reality. Likewise, those illusions demonstrate cases where the world is misaligned with the mind's interpretation, yet the representational object remains intact within the human. Moreover, when referring to intentionality, perception is defined as resembling beliefs or other attitudes, which postulates that illusions involve representational states that fail to match external objects or their properties. This concludes that intentionalism does not require the postulation of mental intermediaries, for instance, sense data.

The Disjunctive Theory

A sensible idea for this theory is its core distinction between the veridical (mind-independent object) and non-veridical (illusion or hallucination) perception. The veridical states that the human observes a mind-independent object in the world (e.g., a real cup in front of you) involving the actual external object, whereas non-veridical defines illusory or hallucinatory experiences as not genuinely seeing a mind-independent object. For this reason, J.M. Hinton argued that veridical perception and hallucination do not need to share a common nature, implying that even when both are indistinguishable from the inside, they do not share identical intrinsic properties. In contrast, intentionalism proposes that both those experiences share an internal representation of which one happens to match reality, while disjunctive theory denies a shared mental representation for both experiences. Hence, seeing a cup in front of oneself, the cup belongs partly to the perceptual state, because its properties create in part the nature of one's perception. Whereas in hallucination, there does not exist such a real cup forming a part of the experience. This difference is displayed by disjunctivism, either seeing actually a cup, where the external object is present, or merely undergoing a hallucination, being entirely internal and absent from the real object. Thereupon, disjunctivism embraces a form of externalism, stating that identical brain states alone cannot guarantee the same perceptual state, due to the veridical experience that involves an actual object in the presence to be experienced. If the neural processes remain the same while observing the object, but the external object disappears (e.g., a person shifts to a hallucination), the mental state changes from the ground on, once the subject is no longer the same type of the perceptual state. Thus, both veridical and non-veridical do not share an internal representation.

Beholder's Share

The Beholder's Share, first introduced by Alois Riegl, later elaborated by Ernst Gombrich, highlights how each viewer actively completes an artwork. Sensory elements such as colours, patterns, shapes, or scenic details initially shape our perception of the piece. However, top-down processes, like prior expectations or learnt associations, further refine our conscious vision. Certainty, perception involves the interpretation and integration of sensory stimuli and expectations, unlike sensing relying only on raw detection of stimuli. For this reason, can perception be seen as an active construction of experience, while sensing as a passive reception of information. Due to the heavily influential nature of context, information about the artist's life or familiarity with their work of art can dramatically shift interpretation, illustrating that the viewer's knowledge and beliefs co-create an artwork's effect. Moreover, the artist's intentions often differ from those of the observer. This lack or conflict of context can completely redirect the emotional or intellectual experience of an artwork. Following this interplay between stimulus input and the observer's framework undermines the deeper principle that perception emphasises a projection of one's internal model onto the external features to construct meaning. As a result, the physical properties of the artwork itself emerge as much from the viewer's interpretive engagement.

Broader Influences

Internal Perception

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

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.

Feelings and Emotions

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 .Therefore hormones hugely affect ones emotions, for example serotonin as the happiness hormone and progesterone for calming.

Perceptional Focus

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.

Social Perception

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.

Stages of Perception

1. Stimulation
2. Organization
3. Interpretation
4. (Memory)
5. (Recall)

Limitations of Human Perception

Limitation

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). Through all these limitations, the human being is determined within its „self“ and „being“.

Components of Perception

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 target is being interpreted. It is possible, that prior expectations impact this interpretation as well as „ambiguous targets [being] especially susceptible to interpretation and addition“. 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."

Philosophical Views

Platos Allegory of the Cave

In Plato's Allegory of the cave, Plato concerns himself with the perception and perspective of the individuals in the cave and the actual reality outside the cave. The allegory deals with the alienated perception of mankind. It also shows the subjectivity of human perception. The people in the cave don't see directly, but only an image of reality. The same goes for different people in our daily life, everyone takes the environment around them differently and interpretations vary, according to their own experience. A modern example of this is when interviewing whitnesses. The implicity statements in accidents for example can be widely different, every witness perceives the truth differently. Here, different descriptions of the course of the accident are often described.

The humans in the cave not wanting to leave it upon hearing about the real world also displays humans being afraid of what they don't know. The question therefore arises whether there is a real correct perception of truth, or as Paul Watzlawick's ook title is also called, "How real is reality?".

Dretske's Approach

Dretske distances himself from the 'Causal Theory of Perception', introducing "a fundamental difference between causal and informational relationship". He "ascribes perception to informational relations […] [and] assigns an important role to information in the explanation of the sensory and cognitive processes [allowing] him to present a clear definitionof objects of perception". According to Dretske the perceived object is a component in the causal sensorial chain about which the the perception carries information. The perceived object is the 'causal antecedent'of the chain as the 'object of perceptual state'. Realized as a primary representation of the object in the perceptual process.

Descartes Method of Doubt - Cartesian Sceptism

In René Descartes Method of doubt, Descartes put all beliefs, ideas, thoughts and matter in doubt. Showing his grounds, reasonings aswell as any knowledge could in fact be false. That any belief that falls prey to even the slightest doubt ,ay be false. Therefore showing, that if there is a way for a belief to be disapproved, the reasonings are insufficient and hence may be doubted. From this work his famous phrase "I think, therefore I am" came about. As the one thimg he couldnt doubt was him doubting, thinking, and him being. Descartes method used four main principles also kmown s Descartes four rules of logic. To accept nothing as true that is not self-evident, unless known to be true. To divide every problem into as many parts as necessary to analyze and solve the problem. To conduct ones thoughts and find the easiest solutions, from the simplest to the more complex in order to proceed. To make enumerations so complete that nothing was omitted, to list every detail of the problem.

The Problem of Perception

Illusion and Hallucination

A problem of perception can be excellently described with a sentence by Nitzsche. "The truths are illusions, of which one has forgotten that they are some". To the problem of perceptual illusion comes the problem of perceptual hallunization. If the perception is clouded by illusions and hallunizations, how can a real direct perception of the world be possible?Answers to this question could be provided by the main theories of experience.

Intentionalism

Intentionalism is the theory that a literal work should be judged in terms of the authors intentions. That the meaning of texts is determined by the intentions of the author. The intent is not only important in writing but also interactions and other parts of perception. Ones intentions can hugely impact the reality of a situation, which may not be perceived rightfully, due to a lack of context and known intent. Knowing the intend is unavoidable to fully understand the reality. If intentions are not known the perception of subjects cannot be considered reality. Therefore intent is a major part to perceiving reality.

Adverbialism

Adverbialism is a theory that describes how people actually receive and feel events. The focus is more on the experience of the object than on the object itself. For example, if a person sees a red object, then he sees this object from a certain perspective in his experience rather than the object itself, in this case he senses the object redly. It should be said that the experience in this case is the red object, but that the experience has been modified so that the experience relates to redness. To summarize, the experience that is gathered is not summarized in a verb but by an adverb. The Adverbialism also endorsed the Common Kind Claim.

The Sensum Datum Theory

The Sensum Datum Theory says that, every experience sensed with the senses, has an object that represent it. This concept of receiving experience is called the act-object conception. The act-object conception also distinct between the mental act of an object being represented and the object, that is being represented. In other word the sense datum theory explains that an object a with the qualities of b, that can be sensed with one of the five senses, like the color or the form consist in is presented with the actual quality of f. The example object would be a red tomato. This objects of the perception are referred as the sense-data. In summary, the sensory experience of an object in the Sensum Datum Theory can be anything that is currently represented, which imprints the perceptible sensual quality of the object into the experience. The Sensum Datum Theory also endorsed the Common Kind Claim.

Bibliography

Tim Crane; Craig French.(March 8, 2005); Imagery and Imagination, Retrieved December 28, 2022, from [4].