Sensation and perception are two similar but distinct processes. When we smell a rose, we get a sensation. How we interpret that sensation (i.e. that smells like grandma) is the perception. Sensations bombard our bodies often without our active control; they bring information about our environment to our brain. Processing that information is the domain of perception. If someone grabs our arm, the feeling of the touch may be the same, but we may interpret it differently based upon who is touching us, when and where. If you want to be a master of touch, you could always look into a course on massage. If you sensed that that was a cheap promotional trick, your perception was correct.
Thresholds and Differences
If you’re taking a basic psych course, they’ll discuss sensations in terms of ‘thresholds.’ In this case, absolute threshold refers to the point at which something becomes a verifiable sensation. We don’t hear or smell as well as dogs because our absolute thresholds are higher. At the same time, an effect that you might normally feel can be mitigated if you’re already feeling that effect. For instance, if you’re holding a heavy weight, you’re not likely to notice the addition of a few ounces. If you’re holding a light weight, you would notice that difference. When you do notice weight is being added, that’s called the just noticeable difference. Weber’s law states that the size of the just noticeable difference is proportional to the intensity of the stimulus. It demonstrates that even our sensory awareness varies based on context. Sensory adaptation defines the process of our body adapting to a stimulus (like when you first feel the shock of jumping into a cold pool, but then you get used to it.)
Perception and Grouping
Much of what we know about perception comes from Gestalt Psychology. Gestalt psychology emphasizes the idea that the whole is other than the sum of its parts. It’s a theory that seeks to uncover how our brain organizes sensory information. For example, we see one object in motion against a backdrop of stagnant, fixed images. We also take into account our history and experiences with those objects. In Gestalt, any singular instance must be evaluated globally. If all this psychology theory is turning you on, you may as well check out this course in Practical Psychology.
Gestalt Laws of Grouping (not Groupon-ing)
Because Gestalt theorists were seeking to understand how our brain organizes information, they came across some of the cheats and shortcuts our brain uses to process new info. Here are the basic Gestalt Laws of Grouping.
- Similarity—Objects that seem similar are grouped together in our minds.
- Proximity—Objects that are close together are seen as going together.
- Good Gestalt—Our brains embrace, follow, and prefer patterns.
- Closure—Our brains prefer to complete a form even when it has gaps.
- Continuity—Objects within other objects are grouped together. We are more likely to group simple items together, like dots, than more complex forms, like jagged lines.
- Common fate—Objects that move together are seen as belonging together. (If half your marbles are moving left and the other half are moving right, your brain perceives them as two separate groups of marbles—not as one.)
- Symmetry—The brain prefers to find one axis of symmetry and will therefore perceive disparate objects as one group in order to confirm symmetry of the whole.
- Past Experience—Under some conditions, your brain interprets objects and activity based on what you have personally experienced in the past.
Are you asleep yet? You’re still with us? Good. Because knowing these principles will help you control other people’s brains. Seriously. Magicians do it all the time. Your brain is Lazy with a capital ‘L’ (though Brain prefers the term ‘efficient.’) All you have to do is control the perception and you control the thought. If you want to make some money on the playground with some cool card tricks, check out this course. For a few more simple magic tricks, here’s one magician who’s revealing his secrets.
One of the best ways to get your head around the difference between sensation and perception is to consider pain. The sensation of pain is one of the most studied and fascinating topics in psychology because studies have repeatedly shown that the perception of pain varies from person to person. In fact, there are a number of factors that influence whether we will experience more pain or less. These include:
- Personality—Anxiety and depression have been shown to contribute to post-operative chronic pain. (Source)
- Placebo effects—Because many people respond to placebos, we know that our brains are wired to respond simply to the idea of treatment to varying degrees.
- Expectations—When it comes to childbirth, coaching and expectations make a big difference. When in favor of a natural birth, women who opt for a doula or midwife to be present have fewer cesareans and medications. Women who fear labor are more likely to require medical intervention.
- Emotional state—You know how smiling can inadvertently make you happier? Our bodies are physiological feedback loops. Pain can trigger a negative emotional state and a bad mood can make us feel pain more severely. (If you’re battling chronic pain, force a smile onto your face and check out this course about the Mechanism of Pain)
Sometimes our brains misinterpret sensations substituting other sensual perceptions for the true sense. Synesthesia is a disorder in which the senses get mixed up. Some patients are able to ‘taste’ music (that Beethoven sonata tastes like scrambled eggs!); others are able to hear a rose. Phantom limb pain, or ghost pains, is another example of our minds misinterpreting stimuli. Almost 90% of amputees with missing limbs experience pains from a limb that no longer exists. But researches have been able to reduce the pain by simply having the amputee do exercises in front of a mirror. The mirror replicates the image of the existing limb, and tricks the brain into thinking the lost limb is still there. Then the brain can perceive the stimulation properly. This shows how our visual sense affects our sense of touch. Phantom pain has also been shown to respond to a virtual reality type of scenario where the arm is shown on screen responding to neural commands.
Studies are beginning to show that we can perceive information below our conscious awareness. Often words are flashed to participants too quickly for someone to perceive them visually, but nonetheless the subjects engage in behavior related to the word (i.e. drinking a beverage after not perceivably seeing the word ‘thirsty’.) This shows that we are susceptible to information even when we don’t give it our full attention.
Attention has a lot to do with our ability to perceive information. We are all well-versed at focusing on one person’s voice in a crowded restaurant. This focused attention is called selective attention. Attention is both selective and shiftable. Magicians capitalize on the fact that we tend to focus on one stimulus at a time by misdirection—asking us to focus on a distraction while the trick takes place. Inattentional blindness results when we are concentrating on a difficult task. If you want to understand more about what really makes people tick, check out this video psychology textbook.
ESP—Fact or Fiction?
Over half of the adults in the US believe in ESP or extrasensory perception. This is the idea behind conjurors being able to read minds and the mother who has a gut feeling that something is wrong before her daughter reports a car accident. While it’s tempting to believe that some people are innately more connected with our environment, seventy-five years of research has failed to produce proof.
All sensation begins with special cell receptors that transmit information to our brain. Our perceptions of that information can be influenced by our attention, or lack thereof, expectations, beliefs and previous experience. We adapt our responsiveness based on the average level of stimulation. If you want to know more about how our senses and perceptions develop, check out this course on Human Development. If you sensed that this article was coming to an end, you were right.