Our sensory receptors are constantly processing information from the outside world, but it is not so much an act of sensing as it is an act of perceiving that is registered in our awareness. Sensation occurs when sensory receptors detect sensory stimuli, while perception involves the organization, interpretation, and conscious experience of those sensations. Another way to think about it is that sensation is a physiological process, whereas perception is psychological. Sensation is about detecting a stimulus; perception is about understanding it.
Although our perceptions are built from sensations, not all sensations result in perception. When a stimulus doesn’t pass a certain threshold, it is not detected by the organism, it is called the absolute threshold and refers to a sheer physiological process. When a stimulus is detected by the sensory apparatus, but does not reach conscious awareness, it is referred to as recognition threshold. There is also a phenomenon called differential threshold, which refers to capacity to perceive the increase in a given stimulus. All of these vary from person to person, but can be changed through practice. We also often don’t perceive stimuli that are constant over a long period, like smells or sounds that are consistent in the environment. Just imagine being inside a training room for a while, as compared to entering it from fresh air—the initial perception of smell is rather sharp when you first encounter it upon entering, but after a while, the stimulus is no longer registered by conscious awareness, even though it still persists in the environment. This phenomenon is called habituation, it helps us function in environments where we are being inundated with sensory experiences and information.
Attention is the major factor in how we perceive sensations. Imagine being in a loud room and trying to have a conversation with someone. In order to do so, you would have to actively ignore all the environmental noise and concentrate all your attention on the person speaking. If someone interrupted you at that moment and asked what song was playing, you would probably not be able to give an answer.
We can say that sensation is passive, and perception is active. Sensing a stimulus is automatic; sensory organs like eyes or ears respond mechanically to light and sound waves without any conscious effort. In fact, it would be impossible to stop this process from occurring unless the organ itself is impaired in some way. Sensing is a data-gathering state, in which information is simply received from the environment. It only involves bottom-up processing. Perception, on the other hand, requires the brain to interpret, organize, and understand the incoming data. It uses both bottom-up and top-down processing, meaning that while it depends on sensory information, it also requires resources like memory, focus, contextual understanding, and even imagination to make sense of the incoming content. Neither of these procedures alone can comprehensively explain the process of perception; we need both for the process to occur.
When your brain is interpreting information from sensory input, it is matching it against previous experiences. It is memory-driven—your expectations and references determine what you perceive. Different people will respond very differently to the same stimulus based on their past experiences. We are all familiar with the five primary senses: sight, hearing, touch, taste, and smell. However, humans possess other forms of perception beyond the direct assessment of mechanical stimuli, which are a combination of several, if not all, senses:
proprioception: the sense of bodily position and movement in space
vestibular perception: balance, detected from motion and orientation of the head
interoception: perceiving sensations within the body, such as hunger, thirst, etc.
thermoception: detection of changes in the temperature of the body and the environment
nociception: perception of pain, tissue damage, and discomfort associated with it
time perception: subjective sense of the passage of time
social perception: interpreting social cues, emotions of others, and intentions
symbolic perception: the capacity to interpret language and abstract patterns of thought
The crucial thing to recognize in relation to the process of perception is that COGNITIVE PROCESSES ARE INSEPARABLE FROM THE BODY! Even though sensing is a passive action that happens automatically, it is guided and activated by the physiological structures in the body and is tightly correlated with movement. When you are looking at an object, even though you may feel as if you are passively observing it, there is a myriad of small movements occurring in the eye to provide a full picture of what is being seen. There is an eye movement called saccades; during each saccade, the eyes move as fast as they can, and the speed cannot be consciously controlled between the fixations. This movement is used to scan the visual scene and obtain a higher-resolution image. When the ear processes sound waves, it also happens in the form of movement: the structures of the cochlea vibrate in response to sound with a specific vibratory pattern. This pattern allows the inner hair cells and their connections to the auditory nerve to send signals to the brainstem and brain about the sound's vibration and frequency content.
When information from sensory receptors reaches the brain, different layers of it must be processed in parallel pathways. For example, the pattern of light entering the eye provides information about an object’s form, depth, motion, and color. All of these categories have to be analyzed and integrated by different regions of the CNS, allowing us to recognize objects, understand their locations, track their movement, and perceive their color all at once, creating a unified perception of what is being seen.
Even though perception is built from sensory information, many of the signals detected through the sensory channels in the body never become actively perceived because of the sensory threshold mentioned earlier. The brain simply does not highlight their presence. Scientists Weber and Fechner formulated a law that describes the relationship between stimulus and its perception as follows: the perception of a stimulus change is proportional to the relative change in intensity rather than the absolute change. In other words, we perceive percentage change, not amount change, in relation to any given stimulus of the same kind. This is an essential notion in perception because it illustrates how even strong stimuli can be completely ignored by the system if it is already overwhelmed. For example, if you turn on a flashlight on a sunny street, you will notice no difference because there is already significant light in the environment. Turning on the same flashlight in a dark room will have a very different result. This is also why, when we experience intense pain, it becomes challenging to sense the body—the nociception overtakes sensory pathways, affecting movement quality. Other factors that block the perception of subtle layers of experience in the body are tension and intense emotional states.
Perception is the result of the physiological process of receiving sensory information and interpreting it through the lens of our experiences and conditioning. This process is closely linked to our memories, and the physiological structures in the brain involved in both are intertwined. Perception helps encode sensory experiences into memory, and memory, in turn, shapes how we perceive the world by adding context, expectations, and meaning. In fact, perception is the initial stage in forming memories, as it converts sensory input into mental representations. For example, when we see a new face, visual perception scans its features, which are then stored in memory for later recognition. What we pay attention to determines what sensory information is encoded in memory, so passive sensing that has not been actively processed by the brain will not have the same relationship to memory. The memories we have, in turn, affect how we perceive things; they provide context for interpreting sensory information, influencing what we see or hear. This makes perception faster on one hand, but can create associations on the other, which can sometimes be problematic. A perceptual set is a tendency to perceive things in a certain way based on prior knowledge or expectations. No two people will perceive things identically, even if they are looking at the same picture, hearing the same sounds, or feeling the same touch. Prior experiences color and define whether certain sensations are recognized as pleasant or not and which emotions they will trigger.
Perception, unlike sensing, can be an active and directed process. By deciding which sensory information to pay attention to, we can enhance and improve our ability to differentiate between various inputs. Many great examples illustrate this: musicians, through training, learn to recognize very subtle differences in pitch that others cannot detect, and sommeliers can perceive refined notes in the taste of wine that others without the same training cannot. Our ability to interpret sensory information and compartmentalize it is tightly linked to our capacity to learn. The better we are at discriminating sensory information, the better our perceptual accuracy, and all learning begins with perception. When we sense a stimulus in the environment and highlight it with our attention, our brain forms a mental template and strengthens specific neural pathways, making it easier to recognize in the future. This helps us to compartmentalize experiences for future learning, but also can create a certain bias, especially for experiences that had a strong emotional tone. Any new stimulus perceived that triggers the memory associated with it will be influenced by the emotion experienced in the first instance, which will affect how the new stimulus is perceived. These processes can be dissociated and worked with through deliberate practice of observing and detecting the connection between a stimulus and the reaction to it.
A principle of affordances, or action possibilities, first introduced by psychologist James Gibson, emphasizes the active nature of perception. It suggests that perception is goal-directed, constantly looking for actionable opportunities. According to this idea, when we encounter objects in our environment, we immediately recognize opportunities to act upon them. This recognition is also tightly connected to our memories, previous experiences, and goals. For example, seeing stairs suggests the possibility of climbing up, a doorknob invites pulling or turning, and a chair offers a place to sit. When we interact actively with the environment and gain experience, we create a more refined and broad understanding of affordances. A parkour practitioner, for instance, would see the urban environment in a much more sophisticated way than someone without such a reference. We can expand our understanding of affordances by engaging actively with the environment and directing our attention to the perception of possibilities within it.
Perception is not a passive experience; it is a skill that involves our physiological, psychological, and sensory mechanisms working in tandem. It is deeply intertwined with the body’s movements and the physiological structures that drive them, and it can be directed and improved. Just as our bodies can be trained to move with agility, our perception can be refined to interpret and respond to the world more effectively. Through deliberate practice, we can sharpen our awareness, enhance the sensitivity of our perceptions, and better recognize the subtleties in our environment. This expansion of perceptual abilities opens up new possibilities for personal growth, enabling us to engage more fully with our surroundings and ourselves. Understanding perception not only broadens our sensory experience but also lays a foundational skill for mastery in any field that depends on fine-tuned awareness and response.