Processing Sensation and Perception

• 16-1 What are sensation and perception? What do we mean by bottom-up processing and top-down processing?

Flip It Video: Top-Down and Bottom-Up Processing

Heather Sellers’ curious mix of “perfect vision” and face blindness illustrates the distinction between sensation and perception. When she looks at a friend, her sensation is normal. Her sensory receptors detect the same information yours would, and her nervous system transmits that information to her brain. Her perception—the processes by which her brain organizes and interprets sensory input—is almost normal. Thus, she may recognize people from their hair, gait, voice, or particular physique, just not from their face. Her experience is much like the struggle any human would have trying to recognize a specific penguin.

sensation

the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.

sensory receptors

sensory nerve endings that respond to stimuli.

perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

Under normal circumstances, sensation and perception blend into one continuous process. In this module, we slow down that process to study its parts; in real life, your sensory and perceptual processes work together to help you decipher the world around you.

• Bottom-up processing starts at your sensory receptors and works up to higher levels of processing.
• Top-down processing constructs perceptions from this sensory input by drawing on your experience and expectations.

bottom-up processing

analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information.

top-down processing

information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.

As your brain absorbs the information in Figure 16.1, bottom-up processing enables your sensory systems to detect the lines, angles, and colors that form the flower and leaves. Using top-down processing, you interpret what your senses detect.

Figure 16.1 What’s going on here?

Our sensory and perceptual processes work together to help us sort out complex images, including the hidden couple in Sandro Del-Prete’s drawing, The Flowering of Love.

At first sight, the drawing shows a white rose with long petals. Its stem is covered in green leaves. In the background, there is drawing of a faded arch. The drawing of the rose has a wooden frame. At the bottom of the frame, there are two red heels and the left leg of a pair of pantyhose. The right one is hanging from one of the leaves. At the top of the frame, a sign with the phrase “La vie en rose” is fixed with a nail. A closer look reveals that the center of the rose petals is formed of a couple embracing.