Basic Psychology: Types of Perception
Contents
- Introduction
- Vision
- Sound
- Touch
- Taste
- Sound
- Touch
- Taste
- Smell
- Social
- Multi-modal perception
- Other senses
Introduction
Perception (from the Latin perceptio, which means "gathering, receiving") is the organisation, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves the transmission of signals through the nervous system, which results from physical or chemical stimulation of the sensory system. Light strikes the retina of the eye, odour molecules mediate smell, and pressure waves mediate hearing.
Perception is formed not only by passively receiving these signals, but also by the recipient's learning, memory, expectation, and attention. Sensory input is the process by which this low-level information is transformed into higher-level information (e.g., extracts shapes for object recognition). The subsequent process links a person's concepts and expectations (or knowledge), restorative and selective mechanisms (such as attention), and perception.
Perception is based on complex nervous system functions, but it appears to be mostly effortless because this processing occurs outside of conscious awareness. Since the rise of experimental psychology in the nineteenth century, psychology's understanding of perception has advanced through the use of a variety of techniques. Psychophysics quantifies the relationships between the physical properties of sensory input and perception. Sensory neuroscience is the study of the neural mechanisms that underpin perception. In terms of the information they process, perceptual systems can also be studied computationally. In philosophy, perceptual issues include the extent to which sensory qualities such as sound, smell, or colour exist in objective reality rather than in the perceiver's mind.
Individuals can perceive the world around them as stable because their brain's perceptual systems allow them to do so even when sensory information is typically incomplete and rapidly changing. Human and animal brains are modularly structured, with different areas processing different types of sensory information. Some of these modules are sensory maps that map some aspect of the world across a portion of the brain's surface. These various modules are linked and influence one another. Smell, for example, has a strong influence on taste.
Vision
Vision is the primary human sense in many ways. Light enters each eye and is focused in such a way that it is sorted on the retina according to its origin. A dense surface of photosensitive cells, including rods, cones, and intrinsically photosensitive retinal ganglion cells, detects the intensity, colour, and position of incoming light. Before the information is sent to the brain, the neurons on the retina process texture and movement. The optic nerve then transmits approximately 15 different types of information to the brain proper.
The timing of perception of a visual event has been measured at various points along the visual circuit. A sudden change in light at a specific location in the environment first changes photoreceptor cells in the retina, which then sends a signal to the retina bipolar cell layer, which can then activate a retinal ganglion neuron cell. A retinal ganglion cell is a bridging neuron that connects visual retinal input to central nervous system visual processing centres. In a rabbit retinal ganglion, light-altered neuron activation takes about 5–20 milliseconds, whereas in a mouse retinal ganglion cell, the initial spike takes between 40 and 240 milliseconds before activation. An action potential spike, a sudden increase in neuron membrane electric voltage, can be used to detect the initial activation.
The presentation of an anomalous word to individuals was a perceptual visual event measured in humans. When these people 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 be recorded on an electroencephalogram (EEG). In one experiment, human participants wore an elastic cap with 64 embedded electrodes distributed across the surface of their scalp. 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, within 230 milliseconds of encountering the anomalous word.
Sound
Hearing (or audition) is the ability to detect vibrations in order to perceive sound (i.e., sonic detection). Audio or audible frequencies are those that can be heard by humans, and their frequency range is typically considered to be between 20 Hz and 20,000 Hz. Ultrasonic frequencies are those that are higher than audio frequencies, while infrasonic frequencies are those that are lower than audio frequencies.
The auditory system is made up of three parts: the outer ears, which collect and filter sound waves; the middle ear, which transforms sound pressure (impedance matching); and the inner ear, which generates neural signals in response to sound. These are led to the primary auditory cortex within the temporal lobe of the human brain by the ascending auditory pathway, from which the auditory information is then sent to the cerebral cortex for further processing.
In most cases, sound does not come from a single source; instead, sounds from multiple sources and directions are superimposed as they reach the ears. Hearing entails the computationally difficult task of distinguishing sources of interest, identifying them, and frequently estimating their distance and direction.
Touch
Haptic perception is the process of recognising objects through touch. It combines somatosensory perception of skin surface patterns (e.g., edges, curvature, and texture) with proprioception of hand position and conformation. Touch can be used to quickly and accurately identify three-dimensional objects. This entails exploratory procedures such as moving the fingers over the object's outer surface or holding the entire object in one hand. Haptic perception is based on the forces felt during touch.
Gibson defined the haptic system as "the individual's sensibility to the world adjacent to his body through the use of his body." Gibson and colleagues emphasised the close relationship between body movement and haptic perception, the latter of which is active exploration.
Haptic perception is related to the concept of extended physiological proprioception, which states that when using a tool, such as a stick, perceptual experience is transparently transferred to the tool's end.
Taste
Taste (formally known as gustation) is the ability to perceive the flavour of substances such as food. Taste buds, also known as gustatory calyculi, are sensory organs concentrated on the upper surface of the tongue that receive tastes. Each of the human tongue's roughly ten thousand taste buds contains 100 to 150 taste receptor cells.
Sweetness, bitterness, sourness, and saltiness have traditionally been the four primary tastes. The recognition and awareness of umami, the fifth primary taste, is a relatively new development in Western cuisine. Other tastes can be imitated by combining these basic tastes, which all contribute only partially to the sensation and flavour of food in the mouth. Other factors include smell (detected by the olfactory epithelium of the nose), texture (detected by a variety of mechanoreceptors, muscle nerves, and so on), and temperature (detected by thermoreceptors). All basic tastes are classified as appetitive or aversive based on whether they perceive something to be harmful or beneficial.
Smell
The process of absorbing molecules through olfactory organs, which are absorbed by humans through the nose, is referred to as smell. These molecules pass through a thick layer of mucus, come into contact with one of thousands of cilia protruding from sensory neurons, and are then absorbed by a receptor (one of 347 or so). From a physical standpoint, it is this process that allows humans to comprehend the concept of smell.
Smell is also a very interactive sense, as scientists have discovered that olfaction interacts with other senses in unexpected ways. [33] It is also the most primitive of the senses, as it is known to be the first indicator of safety or danger, and thus drives the most fundamental of human survival skills. As such, it has the potential to influence human behaviour on a subconscious and instinctive level.
Social
Social perception is the aspect of perception that enables people to comprehend the individuals and groups in their social environment. As a result, it is a component of social cognition.
Speech
Speech perception is the process of hearing, interpreting, and comprehending spoken language. This research aims to understand how human listeners recognise the sound of speech (or phonetics) and use this information to understand spoken language.
Listeners can perceive words in a variety of situations because the sound of a word can vary greatly depending on the words that surround it, the tempo of the speech, as well as the physical characteristics, accent, tone, and mood of the speaker. Reverberation, or the persistence of sound after it has been produced, can also have a significant impact on perception. Experiments have shown that when hearing speech, people automatically compensate for this effect.
The process of perceiving speech begins with the level of sound within the auditory signal and the auditioning process. To extract acoustic cues and phonetic information, the initial auditory signal is compared to visual information, primarily lip movement. Other sensory modalities may be integrated at this stage as well. This speech data can then be used for higher-level language processes like word recognition.
Speech perception is not always unidirectional. Higher-level language processes related to morphology, syntax, and/or semantics may interact with basic speech perception processes to aid in speech sound recognition. It is possible that recognising phonemes before recognising higher units, such as words, is not necessary (or even possible). Richard M. Warren conducted an experiment in which he replaced one phoneme of a word with a cough-like sound. His subjects perceptually restored the missing speech sound without difficulty. Furthermore, they were unable to determine which phoneme had been disrupted.
Faces
Facial perception refers to cognitive processes that specialise in dealing with human faces (including determining an individual's identity) and facial expressions (such as emotional cues.)
Social touch
The somatosensory cortex is a region of the brain that receives and encodes sensory information from all of the body's receptors.
Affective touch is a type of sensory information that causes an emotional response and is typically social in nature. This type of information is actually coded differently than other types of sensory information. Though affective touch intensity is still encoded in the primary somatosensory cortex, the pleasantness associated with affective touch is activated more in the anterior cingulate cortex. Increased blood oxygen level-dependent (BOLD) contrast imaging during functional magnetic resonance imaging (fMRI) reveals that signals in the anterior cingulate cortex and prefrontal cortex are highly correlated with affective touch pleasantness scores. Transcranial magnetic stimulation (TMS) of the primary somatosensory cortex inhibits affective touch intensity but not affective touch pleasantness perception. As a result, while the S1 is not directly involved in the processing of socially affective touch pleasantness, it does play a role in distinguishing touch location and intensity.
Multi-modal perception
Concurrent stimulation in more than one sensory modality and the effect on perception of events and objects in the world is referred to as multi-modal perception.
Time (chronoception)
Chronoception is the perception and experience of the passage of time. Although the sense of time is not associated with a specific sensory system, research by psychologists and neuroscientists suggests that human brains do have a system governing time perception, which is composed of a highly distributed system involving the cerebral cortex, cerebellum, and basal ganglia. The suprachiasmatic nucleus, a component of the brain, is responsible for the circadian rhythm (also known as one's "internal clock"), whereas other cell clusters appear to be capable of shorter-term timekeeping, known as an ultradian rhythm.
One or more central nervous system dopaminergic pathways appear to have a strong modulatory influence on mental chronometry, particularly interval timing.
Agency
The subjective feeling of having chosen a specific action is referred to as a sense of agency. Some conditions, such as schizophrenia, can cause a loss of this sense, which can lead to delusions such as feeling like a machine or being controlled by an outside source. The polar opposite can also occur, in which people experience everything in their environment as if they had decided it would happen.
Even in non-pathological cases, there is a discernible difference between making a decision and having a sense of agency. Methods such as the Libet experiment can detect a gap of half a second or more between the time when there are detectable neurological signs of a decision being made and the time when the subject becomes conscious of the decision.
There are also experiments in which psychologically normal subjects are given the illusion of agency. Wegner and Wheatley, psychologists, gave subjects instructions in 1999 to move a mouse around a scene and point to an image every thirty seconds. However, a second person—posing as a test subject but actually a confederate—held the mouse at the same time and controlled some of the movement. Experimenters were able to manipulate subjects' perceptions of "forced stops" so that they appeared to be their own choice
Familiarity
Neuroscientists sometimes divide recognition memory into two functions: familiarity and recollection. A strong sense of familiarity can occur in the absence of recollection, as in cases of deja vu.
The temporal lobe (specifically the perirhinal cortex) responds differently to novel stimuli versus familiar stimuli. In humans and other mammals, firing rates in the perirhinal cortex are linked to a sense of familiarity. In tests, stimulating this area at 10–15 Hz caused animals to treat even novel images as familiar, while stimulating this area at 30–40 Hz caused novel images to be partially treated as familiar. Stimulation at 30–40 Hz, in particular, caused animals to stare at a familiar image for longer periods of time, just as they would at an unfamiliar one, but it did not result in the same exploration behaviour normally associated with novelty.
Recent research on perirhinal cortex lesions found that rats with damaged perirhinal cortex were still more interested in exploring when novel objects were present, but they seemed unable to distinguish between novel and familiar objects—they examined both equally. Other brain regions are thus involved in detecting unfamiliarity, whereas the perirhinal cortex is required to associate the feeling with a specific source.
Sexual stimulation
Sexual stimulation is defined as any stimulus (including bodily contact) that induces, enhances, or maintains sexual arousal, potentially leading to orgasm. Sexual stimulation is distinct from the general sense of touch in that it is strongly linked to hormonal activity and chemical triggers in the body. Although sexual arousal can occur in the absence of physical sexual stimulation, achieving orgasm usually necessitates physical sexual stimulation (stimulation of the Krause-Finger corpuscles found in erogenous zones of the body.)
Other senses
Other senses allow us to perceive body balance, acceleration, gravity, body part position, temperature, and pain. They can also allow perception of internal senses such as suffocation, gag reflex, abdominal distension, rectum and urinary bladder fullness, and sensations in the throat and lungs.
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