Understanding Sensation and Perception

Sensation: 1) sensory organs absorb energy from the outside environment 2) sensory receptors convert energy into impulses that go to your brain. Taste Touch Sight Sound Smell

What is…? Sensory adaptation: receptors become less responsive to unchanging stimulus and stop sending signals to the brain Not being aware of the clothing you have on, the seat you are sitting in, or the “bad smell” in a room our brain is only interested in changes to information.

Perception: when the brain organizes sensory information and translates it into something meaningful Example: Hearing a sound is sensation, but identifying that sound as a phone ringing is perception

How have our brains evolved to help us perceive the world? Perceptual Constancies: Size constancy: SC: tendancy to interpret an object as always being the same actual size, regardless of it’s distance

Size constancy illusion: Consistent with this, the man in the background appears to be further away from you than the person in the foreground. What is not consistent, however, is that the background figure is not proportionally smaller to its identical counterpart in the foreground.      When a figure normally recedes into the distance, it gets smaller, i.e., its visual angle gets smaller. Here, the background figure remains the same size (and same visual angle) as the foreground figure. Your visual system assumes that since both figures have the same visual angle, but are at differing distances, the one in the background must be larger. This demonstrates that what you see is not necessarily what you perceive.      Your visual system is constantly making inferences based on constraints derived from the regularities of your visual environment.

Perceptual Constancies: Shape constancy: The door is many different shapes, but we still perceive it as the same shape

Shape constancy illusion: We assume that two-dimensional shapes  describe three-dimensional objects. Drawn on the two-dimensional page, the table tops are the same except for a rotation. Convince  yourself that the shapes are the same on the page by making a cotout equal insize to one of the table tops. Then, rotate the cutout  and place it on the other tabletop.

Perceptual Constancies: Brightness constancy

Brightness Constancy Illusion

Perceptual Expectancies: Our perception is affected by our past experiences People perceive smells of “apple”, “melon”, “pepper”, etc in wine… Have you ever seen the shape of a dog or face in a cloud? Can you hear this sound? What image do you see in the following drawing…? Try hearing this sound. It is called “under 20s” sound as the elder’s can’t perceive it. It is a sine wave at 18,000 Hz (by comparison, a dog whistle sounds at 16,000 – 22,000 HZ – meaning a dog can hear this sound as well). This sound is used by some teenagers as a ring tone on their cellphone so that only they (and others of their age group ofcourse) can tell when the phone is ringing. It is also occasionally used in England to play very loud in areas that authorities don’t want teens to congregate in, as the noise annoys them. The inner ear of the humans have a functional design to hear sounds in a range of a frequency. Hearing is not merely a function of ears but the oscillation amplitude is conducted to the brain. As people get older they lose the ability to hear higher pitched sounds. As people get older they lose the ability to hear higher pitched sounds – that is the reason that only young people can hear this sound – it is too high for most people over the age of 20.

Do you see dolphins? The way we see things depends on our frame of mind. In this illusion, Message of Love from the Dolphins, adult viewers see two nude lovers embracing. But when young children look at this image, they see only dolphins.

Which direction do you see this woman spinning Which direction do you see this woman spinning? Can you switch the direction? The spinning girl is a form of the more general spinning silhouette illusion. The image is not objectively “spinning” in one direction or the other. It is a two-dimensional image that is simply shifting back and forth. But our brains did not evolve to interpret two-dimensional representations of the world but the actual three-dimensional world. So our visual processing assumes we are looking at a 3-D image and is uses clues to interpret it as such. Or, without adequate clues it may just arbitrarily decide a best fit – spinning clockwise or counterclockwise. And once this fit is chosen, the illusion is complete – we see a 3-D spinning image.

For more ways to fool your brain based on your perceptual expectancies… Visit: http://www.smashinglists.com/10-amazing-tricks-to-play-with-your-brain/