Before we can understand how the brain reconstructs our world using mental schemas it’s critical to learn how information from the world is first sensed and perceived.

Sensation

The physical process during which our sensory organs (e.g., eyes, ears, nose among others) respond to external stimuli is called sensation. Sensation happens when you eat noodles or feel the wind on your face or hear a car horn honking in the distance. During sensation, our sense organs are engaging in transduction, the conversion of one form of energy into another. For example, physical energy such as light or a sound wave is converted into a form of electrical energy that the brain can understand.

Perception

After our brain receives the electrical signals we make sense of all this stimulation and begin to appreciate the complex world around us. This psychological process, making sense of the stimuli, is called perception. It is during this process that you are able to identify a gas leak in your home, recognize the color orange, or connect a song that reminds you of a specific afternoon spent with friends. Perception is the process of interpreting and organizing the information that we received from our senses.

Our experience influences how our brain processes information. You have tasted food that you like and food that you don’t like. There are some bands you enjoy and others you can’t stand. When eat something new or hear a new band, you process those stimuli using bottom-up processing. This is when we build up to perception from the individual pieces.

Sometimes stimuli we’ve experienced in our past will influence how we process new ones. This is called top-down processing. The best way to illustrate these two concepts is with our ability to read.

Read the following quote out loud:

Notice anything odd while you were reading the text in the triangle? Did you notice the second “the”? If not, it’s likely because you were reading this from a top-down approach. Having a second “the” doesn’t make sense. We know this and our brain knows this and doesn’t expect there to be a second one, so we tend to skip right over it. In other words, your past experience has changed the way you perceive the writing in the triangle. Someone who is just learning to read is using a bottom-up approach by carefully attending to each piece and would be less likely to make this error.

Attention

Attention is the behavioral and cognitive process of selectively concentrating on one thing in our environment while ignoring other distractions. Attention is a limited resource. This means that your brain can only devote attention to a limited number of stimuli (things in the environment). Despite what you may believe, we are terrible multi-taskers. Research shows that when multitasking, people make more mistakes or perform their tasks more slowly. Each task increases cognitive load (the amount of information our brain has to process) and our attention must be divided among all of the tasks to perform them. This is why it takes more time to finish something when we are multitasking.

Many aspects of attention have been studied in the field of psychology. In some respects, we define different types of attention by the nature of the task used to study it. For example, a crucial issue in World War II was how long an individual could remain highly alert and accurate while watching a radar screen for enemy planes, and this problem led psychologists to study how attention works under such conditions. Research results found that when watching for a rare event, it is easy to allow concentration to lag. This continues to be a challenge today for TSA agents, charged with looking at images of the contents of your carry-on luggage in search of knives, guns, or shampoo bottles larger than 3 oz.

Culture can also influence and shape how we attend to the world around us. Masuda and Nisbett (2001) asked American and Japanese students to describe what they saw in images like the one shown below. They found that while both groups talked about the most salient objects (the fish, which were brightly colored and swimming around), the Japanese students also tended to talk and remember more about the images in the background (they remembered the frog and the plants as well as the fish).

North Americans and Western Europeans in these types of studies were more likely to pay attention to salient and central parts of the pictures, while Japanese, Chinese, and South Koreans were more likely to consider the context as a whole. The researchers described this as holistic perception and analytic perception.

Holistic Perception: A pattern or perception characterized by processing information as a whole. This pattern makes it more likely to pay attention to relationships among all elements. Holistic perception promotes holistic cognition: a tendency to understand the gist, the big idea, or the general meaning. Eastern medicine is traditionally holistic; it emphasizes health in general terms as the result of the connection and balance between mind, body, and spirit.

Analytic Perception: A pattern of perception characterized by processing information as a sum of the parts. Analytic perception promotes analytic thinking: a tendency to understand the parts and details of a system. This pattern makes it more likely to pay attention and remember salient, central, and individual elements. Western medicine is traditionally analytic; it emphasizes specialized subdisciplines and it focuses on individual symptoms and body parts.

How we attend and perceive our world has implications for how we evaluate and explain the world around us, including the actions of others. We will talk more about this concept, known as attributions, later in the chapter.