Throughout the course, I struggled to understand the difference between bottom-up and top-down processing as it relates to perception. Bottom-up processing is any processing that originates with the incitement of the sensory receptors. Top-down processing always begins with a person’s previous knowledge, and forecasts due to this already acquired knowledge. While I was driving home one day, I had quite the realization while stopped at a stop sign. The interplay between bottom-up and top-down processing had actually caused me to stop at the stop sign. It became quite obvious how the two processes work in harmony in order to make this world negotiable for a human being. It seems that the two operate together more often than not, which, at times, makes them difficult to distinguish between.
It seems that driving an automobile is a great example of the teamwork between bottom-up and top-down processing. Some of our seemingly automatic reactions when we are driving a car are due to bottom-up processing. If a deer runs out in front of our car, we will most likely attempt to avoid a collision reflexively. We have perceived the deer through our visual receptors, and come to a stop. This has occurred without much conscious consideration and prior knowledge needed. The processing of this event appears to have happened by dominantly bottom-up means.
What about the stop sign? Is this bottom-up or top-down? I believe the correct answer is: both. In order for me to consider this stop sign, I must first visually perceive the octagonal red sign we all know so well. This initial perception comes from the environment and appears to be bottom-up. But, how do I even know what a stop sign is? I know the action I must take when this stop sign is perceived due to top-down processing. This is rooted in our knowledge and information about previous experiences. Previously, in my life, I learned about the concept of a stop sign, and what to do when encountering one while driving. I cannot perceive the stop sign in the environment without bottom-up processing, and would also have no idea what to do with this visual information without my previous experience with the theory of top-down processing. I know what side of the road to drive on, green means go, and essentially all of the rules of the road, seem to rely on both bottom-up and top-down processes in discussing perception.
There is enough information in our environment to make sense of the world in a direct way. Information provided to our senses by the environment is all that is needed in order for us to interact with our surroundings. The idea of a stop sign seems to contradict this assessment. If I were to simply perceive the shape, color, etc. of a stop sign without any top-down processes occurring, I would not know the meaning of the sign. This lack of knowledge would result in accidents.
Instead of struggling between both processes separately, my stop sign revelation has made these concepts clearer. This duality seems to occur quite regularly in our everyday lives, and is essential to our negotiation through this world.