Perception: Difference between revisions

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 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.<ref name=":0" /> Along with Descartes analytical approach, raw light signals are simplified into features such as edges and movements by the visual cortex, then recombined under guidance of attention and memory. This creates a synergy between modern neuroscience and analysing complex phenomena into smaller elements.IF

Moreover, 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" />

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" /> 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 a overcross of auditory sensationa and perceptual belief.IP

Perception requires a casual link between an external object and 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, were a blocked pathway (e.g., a mirror) exits 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 can the individual not 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 form those intuitive philosophical standpoints, where participants believe that genuinely perception can occur even in Non-Blocker scenarios, as shown by studies.<ref>Roberts, P., Allen, K. & Schmidtke, K. Reflective Intuitions about the Causal Theory of Perception across Sensory Modalities. ''Rev.Phil.Psych.'' '''12''', 257–277 (2021). <nowiki>https://doi.org/10.1007/s13164-020-00478-6</nowiki></ref> This discrepancy raises questions about whether causal condition is truly a conceptial 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.IP