In chapter four of the Lilienfeld textbook, the concept of 'parallel processing' is described as a human being's ability to pay attention to multiple sense modalities at the same time. There are two critical ideas that are involved in parallel processing; the first is 'bottom-up processing'. This idea can be explained as the process in which human beings perceive an object through looking at all of its parts. The second critical idea involved in parallel processing is 'top-down processing', which refers to the manner in which beliefs and expectancies influence how humans perceive objects. I find parallel processing to be a relevant concept in my everyday life as it allows me to understand my surroundings (i.e. it allows me to comprehend what it is that I am looking at).
Several times a week I drive my car from my house to my place of work. I am able to drive to work safely because I understand how to read traffic signs and traffic lights. Before learning about the parallel processing concept, I thought I understood how to follow street rules because I learned from a driving instructor and because I know how to read. However, I now know that there are several more factors that explain why I am able to follow traffic sign/light rules while driving (parallel processing). For example, when I see a red, hexagonal shaped stop sign on the corner of a street, I know to stop because of the sign's shape (hexagon), color (red), and text written on it (the word 'stop'). My brain understands to perceive the sign as a traffic sign that must be obeyed due to bottom-up processing; I perceive the object through looking at all of its parts. If I were to only perceive the stop sign as a hexagon on a pole I would not understand the object, thus I would not stop and would continue driving and risk crashing into another moving vehicle. Thanks to parallel processing, I perceive the stop sign in its entirety and am able to understand its function and meaning and am able to avoid a possible car collision.
Here is a BBC special that goes in depth about the parallel process that occurs in our brain. It explains how when there is a malfunction/damage to the brain, the process does not work entirely.
Towards the end of part 1 of the special, at 9:00, explains how parallel processing works in the brain.
Part 2 of the video, beginning at 2:10, explains how the recognition system of the human brain turns seeing into understanding. At 3:35 the video begins to provide an example of how brain injury can alter the recognition system with the story of a man named Lincoln Homes.