Captain Psychology

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What Is Perception

Perception of touch

Sensation and perception go together. Our senses input data about our environment. All we know of the world comes through our senses. Vision is not our only sense but it is very well researched.

Perception is what we do with the raw data of sensation. We collect and interpret what we sense, build mental structures to explain it, and use our analyses to inform our decisions.

Sensation-Perception also has a cognitive component. In addition to the bottom-up process, there is top-down processing. We are not passive processors. We look ahead to the incoming information and determine ahead of time how we are going to process it. We are always alert to language. When we hear a sound, we process it as music or language, depending on our initial impression.

Perhaps perception could be categorized as sensational, perceptual and cognitive. How light passes through the eye and is transformed into neural impulses is sensory. Illusions and Gestalt processes are perceptual. And the top-down processing and organizational principles are cognitive.

As a low-vision person, my sensory input differs from most people. I don’t see that they see. My color vision is good but my focus and clarity are off. Yet my perceptual system works fine. I have trouble getting good data input but process well what I see. In addition, there are cognitive rules about how information is organized.

Perceptions is variously labeled sensation, perception, sensation perception, and introduction to cognitive science. Sensation is the collection of information. Perception is the processing of the information. And cognitive science is the study of what goes on inside the head.

Our reliance on our senses is why perceptions is a central component of psychology. Psychology’s earliest research was on perception. Wundt’s laboratory was dedicated to discovering more about how we perceive the world. Perception is about how we interact with our environment.

Here are some types of perception.

Proprioceptive. Processing of kinaesthetic information. The sensing of force, load and movement of body and limb. We keep track of joint position, tendon tension and the amount of muscle contraction.

Temperature. We don’t have temperature receptors, as much as we have temperature-sensing systems. Thermoreceptors are nonspecific. They are sensory nerves that also respond to changes in temperature. We have three major sensations: cold, warm, and extreme. Cold sensing neurons are 3x more common than warm because we can die from being cold.

Cold signals are carried on both on slow, unmyelinated C fibers and on fast, myelinated A Delta fibers. This gives us a fast reaction to acute cold, and a chronic, dull cold feeling. The firing rate of these neurons increases as the temperature drops, and decreases as you get warmer.

Warm signals are carried on unmyelinated C fibers. They increase their firing rate as temperatures rise, and settle down as things cool off.

There are no sensors for hot. The cold and warm systems work together to indicate it.

Extreme temperatures seem to be detected by triggering a pulse or short burst, either by triggering hot and cold receptors simultaneously, or by triggering sensory nerves which sense both hot and cold. This pulse travels quickly to the brain, telling you to put down the frying pan. It doesn’t tell you if the pan is horror cold, only that it is extremely one or the other. This is called paradoxical cold. The slower firmer send information that arrives later, letting you know if the pan just came out of the freezer or the oven.

In addition to the skin, the body gets temperature information from the cornea, mouth and liver. Internal body temperature is sensed and controlled by the hypothalamus.

Sensing is so vital to our survival that it is a complicated process. It processes absolute and relative changes in temperature with our having to think about it.7

Visceral. Most of the time your gains behave themselves and remain quiet. You don’t bother them, and they don’t bother you. Visceral sensations include nausea, bloating, and fullness. It also how you sense stress, gut feelings, and anxiety. In addition to signals from unspecialized nerves, visceral inflammation comes from intraganglionic laminar endings (IGLE) neurons, which have flattened branches. Or from long parallel branches of intramuscular arrays (IMA).

Hearing. Air waves that hit the ear are amplified and converted into neural impulses . The outer ear and middle ear are air pressured, balanced by air flow in the Eustachian tubes. The inner ear is self-contained, fluid filled, and holds the cochlea. Signals are then sent through several stages before reaching the temporal lobes. Our sound sensing system is not easily fooled.

Vision. The visual system processes a large amount of information but is easily fooled. We watch movies and videos composed of images quickly flashed and feel like we are watching real life. But it only take 24 fps or so to fool us. Light passes through the eye, is converted to neural impulses, preprocessed in the LGN, and then fully processed in the occipital lobes. This is the sensory system most studied and best understood.

Touch. We have a system of mechanical receptors. They inform us about touch, pressure, vibration and skin tension. These are low-threshold receptors, meaning it doesn’t take much stimulation to trigger the. They are not evenly distributed in the body. There are a lot of them on figure tips, lips, and other sensitive areas, and less where small distinctions aren’t that important. Elbows may be important but aren’t good at finding small ridges on objects. Fingers are much better at detecting texture.

We have two types of touch receptors. Some measure light touch; some respond to deep touch. Light touch receptors are close to the top of the skin. Deep touch receptors are deep down in the skin. Each positional placement has two types of receptors.

The most common receptors are Meissner’s corpuscles (40%). They are close to surface, rapid adapt, and are great at detecting texture and low vibrations. Meissner’s fire once when you touch an object, and once when you stop touching it. This onset-offset pattern marks the beginning and ending of an event.

Merkel’ s disks are the second most common touch receptor (25%). They like close to the surface, are slow adapting, and are great for sensing light pressure needed to detect shapes. Merkel’s provide continuous firing for as long as you hold an object.

If Meissners and Merkels live upstairs, Pacinian and Ruffini’s corpuscles live in the basement and report deep pressure. Pacinian corpuscles are more onion shaped than Meissner’s, respond to high frequencies, and adapt more quickly. They represent only 15% of touch receptors but they report onset-offset information. Ruffini’s corpuscles are the least understood. They account for about 20% of touch receptors, are located deep in the skin, are slow adapting, and report sustained pressure. They tell you where in your hand a coin is.

Haptic. This is the sensing of moving touch.

Smell. We have a deduction system of airborne molecules. All smells are small molecules. Smell (Olfaction) helps us detects important nutrients, and warns us about bad food or poison. Rancid meat and bathroom smells are more than unpleasant; they warn of potential harm.

You have 10 million smell receptors in your nose. Essential, they are nerve endings exposed to air. Our analysis of the small molecules that flow into our nose is coded into neural impulses. How it is coded is unknown. No one theory has strong evidence to support it. But neural pathways lead from the olfactory mucosa directly to the olfactory bulb.

The olfactory bulb sits right under the most frontal portion of the brain. It processes smells, and sends signals to the orbitofronal cortex to identify the smell, to the amygdala for emotional reaction, and to the parietal lobe for location.

Taste. This is a companion process of smell. Taste (gestation) is the detection of molecules in a solution. When we put something in our mouth, saliva tries to break it down into a liquid. If it already is liquid, we begin the analysis.

We are looking for carbohydrates, which we need to survive. And for sodium chloride, which we also need. There is a reason we like sweet and salty food.

Taste also protects us. Poisons are mostly bitter, so we have an aversion to bitter tastes. And as food rots, it turns acidic, so anything too sour is also avoided.

The tongue has taste buds, which are grouped in bundles of 30-100 cells. Under a microscope they look like red dots with tiny mushrooms on them. The receptors are wired many to one. They don’t have axons. Like smell it is more like nerve endings being directly stimulated.

Patterns of neural firing are somehow coded, and the information is passed on to the brain. The parietal lobe processes the taste. The frontal lobe determines flavor; the amygdala emotional response. The temporal lobe pulls up memories of similar smells, Grandma’s house and times long past.

Notice that taste and flavor are not the same. An Apple, onion and potato all have the same taste. Flavor is composed of: taste, smell, touch (texture), temperature, color, and sometimes pain.

Vestibular. Another mechanical sense, like touch, vestibular sensations occur in the inner ear. They track head position, bending, spatial orientation and balance. Signals come from the semicircular canals, neck muscle “stretch” receptors, the utricles, and the otolith organs.

Itch. Just talking about it can produce sensations of itchiness. When tissue is damaged, histamine is released. Histamine activates neurons in spinal cord which both produce a chemical called gastin-releasing peptide and sends slow neural impulses to the brain. Once alerted, the brain looks for the cause of problem and tries to resolve it by scratching the irritant off the skin.

Itch is not pain. In many ways itch an pain are opposites. Opiates cause less pain but increase itch. When we scratch it causes pain which stops the itch but causes damage which causes itch.

Pain. All tactile senses except pain adapt quickly. There are two independent systems for pain: sharp and dull. Treatments for one often don’t work on the other.

Time. There are no receptors for time. There are special receptors in the eyes for light level, which we pass on to the pineal gland and hypothalamus for sleep and circadian rhythm adjustment. But, in general, we are not good at treating time.

 

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Photo by Yoann Boyer on Unsplash

‘There are two great principles of psychology: people have a tremendous capacity to change, and we usually don’t.”   Ken Tangen