You are laughing out loud and simply having a good ol' time while walking down an alley. Everything seems perfect, and you just can't stop smiling throughout the entire night. You and your friends are dancing like crazy kids, and everybody is having a good time.
But fast forward to the following Monday. You walk down the same exact alley after school. This time, you are alone. All of your friends are no longer around you. You start to feel a bit anxious as your eyes sharply dart left and right. You don't really remember the street lights being turned off, and every step you take seems to create an endless ruckus. It smells like something died, and you feel beads of sweat crawling down the sides of your face.
Hmm... This seems awfully confusing. Why does the alley feel completely different from last week? Was it something you ate? Is it something in the air? When you went down the alley last time, you felt completely fine.
Nah, blame it on the signal detection theory.
Every second, our brains receive loads of information from our senses. Perception is how we interpret and process all of this incoming information. The signal detection theory is one of the many perceptual theories known to date. This theory states that the level of things you can detect depends on your expectations, your physical and psychological state, and the intensity of those things.
So, think back to when you were walking with your friends. At that time, you were having way too much fun to be more aware of the darkness, cluttered environment, creepy noises, and strange smells. You were simply not motivated to pay more attention to these things, so your ability to detect different signals was interrupted. However, when you were alone, you didn't have those distractions to bother you. Everything around you seemed to be more intense despite the fact that you were in the same exact alley in both situations.
Our power to perceive things is a lot more complicated than we think. Can you think of other examples of the signal detection theory affecting your life?