by Tiara Paul
While sensations reflect the raw nature of stimuli we pick up from our surroundings, perception is defined as our final experience we build of the world. Perception goes hand in hand with cognition; the way our brains process information, drawing from preexisting knowledge and identifying connections, is what impacts our interpretation of this “raw” data from our human senses. The picture below illustrates how we interpret simple sensations into more meaningful perceptions. In Chapter 4, the Gestalt principles describe how the whole is greater than the sum of the parts. For instance, we see a variety of cues (jumble of colors) but perceive with meaning (face of a friend).
Source: https://www.youtube.com/watch?v=0SErqVGcAR0
Illusions can be used to study perception. Cognitive illusions make us do a double take because they indicate how our expectations influence our perceptions. Typically, our perceptions help us perceive the world, but illusions fool us by tricking our natural perceptions, making us see things that do not exist or that are incorrect.
One example is the Ames room. I went to the Museum of Illusions in New York City this past summer and took a picture in the Ames room, but it was not until Psych 100 that I understood the concept! The Ames room is an illusion whereby the room is not what we typically consider a room. It is not a rectangular cuboidal volume. Rather, the floor, ceiling, and side walls are trapezoidal in shape. Opposite walls are not parallel and adjacent walls are not perpendicular at right angles. Rather, the walls are slanted outward. The floor is not level. Rather, it is on an incline where the far left corner is lower. These features show how our natural perceptions deviate from reality. The illustration below displays the true shape of the room: an irregular quadrilateral. We perceive two figures to be standing next to each other, but in reality, one is in a farther corner of the room, resulting in a flawed perception of both size and depth. Typically, the monocular depth cue of relative size tells us that smaller objects are perceived farther away. However, the Ames Room illusion prevents us from noticing this reality.
Source: http://editorial-ink.us/ames-room.asp
The consequence of the Ames Room is that if people who are the same size stand near each other at the far corners of the room, it appears that one is extremely tiny and one is very large. In the picture below, I am standing on the far right with my friend; we are both 5’3”. On the left, the two boys are 6 feet tall, but in the Ames Room, they appear to be considerably shorter than us.
Additionally, it is worth noting that in a video of the Ames Room, our idea of perceptual constancy is challenged. In this phenomenon, we perceive a stimulus as constant despite changes in sensation. Typically, with perceptual constancy, our percept is the same even though the sensations an object creates on our receptors is changing. The Ames room challenges this.
Example: https://www.youtube.com/watch?v=hCV2Ba5wrcs
For this blog post, I purposely explained the room first before showing the picture in order to reverse the normal order in which we witness illusions. Perhaps by first learning the “trick,” you were able to view the picture accurately instead of being fooled by your perceptions. In a slightly different way, relating to memories, this reflects bias. Bias is one of Daniel Schacter’s 7 Sins of Memory, whereby we align memories to our current beliefs, an example of distortion.
In these ways, illusions allow us to understand how perceptions, our final experience as a result of processing raw sensations, works because they show how our expectations influence what we perceive.