Perception and Detection

Sensory data, such as sight, sound, smell, temperature, taste, touch, pressure, movement, location, or changes in the environment, are detected by sense organs (eyes, ears, skin, etc.) and then translated into nerve impulses. This is the process of transduction. 
 
These impulses travel along afferent nerves of the spinal cord to the dorsal root, which relays raw data to the brain’s reticular formation and then on to the thalamus (and hippocampus relay system) where the brain reconstructs outside reality by separating stimuli into specific types of input—mapped to neurons in appropriate sensory areas of the cortex. Sensory stimuli has to travel through the spinal cord, the cranial nerves, the brainstem, the reticular activating system, and then get processed through the thalamus, which weighs the importance and urgency of the messages.
 
Most data gets discarded and is never translated into “meaning” packets. However, the patterns of data that we perceive do get signified or “tagged” with salience. This is how we are able to interpret the importance of data, and predict the outcome of events (whether something is a threat, or that there are constellations in the stars, or that when waves recede from the beach, they will soon come crashing back in). 
 
The hippocampus then either sends the new data to the appropriate area of the cortex to be stored as memory, or further processes the messages sent to the hypothalamus or the amygdala. The hypothalamus activates the pituitary gland to trigger messages to the other glands to secrete hormones and neurohormones and then an enormous association process occurs where a complex interpretation and translation of these messages is turned into something meaningful. 

The human nervous system is finely tuned and highly sensitive and is constantly processing information, perceptions and sensations from the environment; and sending messages back and forth from the body to the brain. Each message can trigger a cascade of physiological responses —hormonal, neurochemical, metabolic, cardiovascular, and muscular—which result in emotional, cognitive, and behavioral responses and actions.

This process is a reconstructing of reality that is dependent on our personal biological, neurological, and genetic make up; which are all changing from moment to moment. It does not function the same way that a security camera records images or a multitrack recorder records sound. In addition to each instrument (or human body) being different and constantly changing, there are other issues that get in the way of perceptual fidelity. 
Link to Papers on 
Perception and Belief
The human brain is composed of about 100 billion individual cells, and there are about 500 trillion connections between those neurons. The brain also contains one trillion glial cells which provide a “scaffolding for the neurons” and other important functions. Each neuron is linked with hundreds and thousands of others, forming simple and complex neural networks that hold specific information about the behaviors, beliefs, emotions, memories, and body sensations associated with specific experiences.  
As the main communications grid of our bodies the nervous system needs time to absorb and digest any new information it receives from the outside, otherwise it can be overloaded, “burned out” and functionally impaired—with a detrimental impact on everything from our capacity to learn, our relationships, mood, health, and our society.