Feature Integration Theory is a very important aspect of modern Psychology an Neuroscience in that it seeks to explain how human beings and other organisms integrate features of objects in the overall perception of said object. Is the entire object put together as one big thing or is it selectively and individually pieced together according to numerous features such as, but not limited to size, color, texture, etc.? This is interesting, especially in regards to complex structures that have a wide variety of components to them selves.
Biologically, different parts of the brain are used to process different things. An example is that vision is processed within the occipital lobe, faces are processed in the temporal lobe, etc. There is even a part of the brain that is specific for direction in regards to physical space and how to get to places. Feature integration theory seeks to understand how the brain does this and how it ultimately brings it all together into a single picture. An important thing to remember is that we technically do not see through our eyes. What we perceive visually is actually our minds replication of what is before us, using color as a means to identify light by its wave lengths. The brain somehow pieces together a perfect picture of all that is before us, with every individual object and all its features displayed prinstinely.
Specific neurons are fired according to various factors. The cones and rods upon our retinas in the backs of our eyes fire according to whatever kind of wave length they detect and color is made through this process once the light is transducted into chemical signals along the optical nerve and into the visual cortex in the occipital lobe. Cones, which function best in bright light, have at least three types that each correspond to either red, blue, or green color, respectively. Also, Studies have shown that at least thirty two areas of the brain become active during visual processing of a stimulus after the light is transducted, which seems to prove the point of feature integration theory that everything is pieced together individually before the final perception is made. The pre-attentive stage is when the object and all its features are analyzed and the focused attention stage is when everything is pieced together and thus, perception is achieved. Although scientists are not sure how all of this works, this seems to be the likely truth about how perception is achieved visually.
Experiments that seem to show that such have helped to pave the way in understanding. The man who pioneered this theory, Treisman, conducted an experiment to showcase it. He showed to numerous subjects a picture involving four objects concealed by two black numbers. The display was flashed for not even a second long and was succeeded by a random-dot masking field that appeared on screen to eliminate “any residual perception that might remain after the stimuli were turned off,” as he explained it. The subjects were to report the black numbers they saw at each location where the shapes had previously been. The results verified Treisman hypothesis. 18% of the time, subjects reported seeing shapes “made up of a combination of features from two different stimuli,” as he explained it even when the stimuli had great differences. Specifically, this result is called illusory conjunction and it is known to occur in various situations. The feature integration theory explains illusory conjunctions; because features are independent of each other during early processing and are not associated with a specific object, they can easily be incorrectly combined both in laboratory settings and in real life situations.

In my own life, vision is something I work with in my practice of gazing. I believe in alternative religion (AND NO, I’M NOT A DEVIL WORSHIPER!) and without going into much detail about my personal beliefs and overall practices, I will recollect one of them (the art of gazing into various substances such as a mirror, a black bowl filled with water, a crystal ball, etc.). The purpose of this and other practices, although not taken seriously by science or by most of the world for that matter, is to allow the mind to perceive insight into the future and the present with regards to various situations and all is made possible by metaphysics. Once one stares into the reflective surface, said one sees all that is reflected in it and all the features of said objects. Initially, they are firm and adamant and detailed with vigor, but as one lets their consciousness and vision fade away, the details begin to fade and one can still recognize some features, but not others. Within a short amount of time, the vision is totally blurred and one is left to the universe to show them what they are trying to gain insight to.  The point of me recollecting this experience (IS NOT TO FREAK EVERYONE OUT!!!!!) is to clarify that oftentimes when one lets their mind fade out gradually and as vision blurs, throughout the process, features also blur while others remain only to blur later on. This seems to support feature integration theory. This, obviously, is not something most people will understand or take seriously, but speaking from my experience as a Neo Pagan, it speaks truth to me.

In conclusion, feature integration theory seeks to explain how our brains piece together individual aspects of objects into one large picture that is what we see. No one is exactly sure of how this happens precisely, but this theory is a great start at uncovering the mystery.

References
Elbich, D. (2016) Lesson 4: Feature Integration theory. Retrieved from Lecture Notes Online Web site:
Goldstein, B. Sensation and Perception. 1980.