Sensation
Sensory receptors in our sense organs respond to information in the world and send this to the brain, a process called sensation. For example, light causes changes in eye cells which relay messages to the nervous system. We call this information stimuli.
You probably know about our five major senses, but were you aware we also have systems that provide information about balance, body position, movement, pain, and temperature?
Our sensory systems:
- Vision
- Hearing (audition)
- Smell (olfaction)
- Taste (gustation)
- Touch (somatosensation)
- Other senses: Balance (vestibular sense), body position (proprioception), body movement (kinesthesia), pain (nociception), and temperature (thermoception)
Perception
Our sensory receptors are constantly collecting information from the environment. However, our interactions with the world are affected by how we perceive that information. Perception is how we interpret sensory information either automatically (bottom-up) or based in knowledge (top-down)[1]. For example, imagine searching for keys: you focus on a yellow key chain in sensible places. This is top-down processing influenced by knowledge and expectancy.
Now imagine sitting in a crowded restaurant eating lunch and talking with others. Suddenly, there is a loud sound of breaking glass and clang of metal pans hitting the floor. That crashing sound would likely grab our attention – our brain would have no choice but to notice the sound and then interpret it. Because this attentional capture was caused by the sound from the environment: it would be considered a bottom-up process.
Sensation vs perception
One way to think of the difference between sensation and perception is to remember that sensation is a physical process, whereas perception is psychological. For example, imagine walking into a kitchen and smelling the scent of baking cinnamon rolls, the sensation is the smell receptors reacting to the odor of cinnamon and sending information to the brain, but the perception might be “Mmm, this smells like the holiday bread that Grandma used to bake when I was a kid”.
Sensation is physical; perception is psychological. Smelling cinnamon is a sensation; recalling holiday bread is perception.
Although sensation and perception are defined as separate processes, they are almost impossible to separate, since each influences the other. For example, the strength of a sensation changes with sensory adaptation: If you burn a cake, you might stop noticing the smell after a while, but your roommate will smell it right away.
Similarly, attention affects what we sense and perceive. In a noisy environment, we can tune out background noise to focus on a conversation (top-down processing). Attention determines what we notice in our environment.
The Influence of Culture and Experience
Cultural psychologists, like Shinoba Kitayama and Richard Nisbett and their colleagues, have conducted multiple studies on the effects of culture on visual perception.[1] In gener