Tag Archives: perception

Staring Statues, A Top-down Processing Illusion

When I was a little girl, I loved going to Disneyland. My family only went about once a year, but each time I went, I just had to ride the Haunted House! Filled with flying ghosts, stretching pictures and singing statues, the Haunted House was as much magical as it was terrifying for me. One particular illusion I found fascinating was of two, white statue heads that stared at me as I walked through the hall of portraits. Each year, I would linger a little longer, staring back at those statues, wondering how they were staring at me at the same time other people claimed that the statues were staring at them. One year, I was bold enough to take a closer look and, to my surprise, they were not statues at all! In fact, instead of being convex, they were actually concave. This fascinated me even more, especially because they continued to look like rounded, white statues even after I knew that they weren’t. Recently, I learned that an illusion like this is achieved by something called top-down processing (Goldstein, 2011).

Top-down processing occurs when we look at something and our previous knowledge or expectations influence how we perceive what we are looking at (Goldstein, 2011). In the case of the two statues in the hall of portraits of Disneyland’s Haunted House, previous experience with looking at a statue of a person’s head, as well as the innumerable amount of times I had looked at a person’s face, would cause me to expect that the statues and their faces were convex. Therefore, when I looked at the concave, white molds of statue heads, lit up in a dark room and surrounded by a thick black border, I perceived them as curving outward toward me.

You may be wondering why Disney didn’t just choose to use normal, rounded statues. I thought the same thing. The park is filled with mechanical dolls and puppets, so why wouldn’t they just do the same for these statues and make them mechanically follow people as they walk by? They could have, but then they would not have been able to achieve the illusion that the statues were staring back at every individual at the same time. Again, because of top-down processing that happens in our brains, each person is experiencing the illusion based on their own prior experiences and expectations (Goldstein, 2011). The statues would appear to follow me as I walked past them because the part of the faces that got cut off, from my point of view, due to them being concave and not convex, is what I’d expect a person’s facial features to look like, according to my past experience, when looking at me from that angle. Meanwhile, another person could be walking in the opposite direction of me and for the same reasons the statues would look as if they were looking at them.

Finally, you may be wondering why the illusion continued to work, even after acquiring the knowledge that the statues were actually concave molds facing away from me. As the narrator of the video “Hollow Face Optical Illusion – VisualFunHouse.com” states, we have such a large amount of knowledge containing faces with noses that stick out, that the top-down processing overrides any signals from the receptors in our visual senses that says otherwise.

So the next time you get a chance to visit Disneyland or Disneyworld or maybe even a nearby haunted house during Halloween, make sure to take a closer look at what kinds of illusions you may be experiencing due to top-down processing. It’s amazing the way our brains work! To experience the illusion now, check out the following two videos…

Hollow Face Optical Illusion – VisualFunHouse.com

and

Hollow face illusion by John Kubie, author of “Depth Perception and The Hollow Face Illusion” on BrainFacts.org.

Reference

Goldstein, E. B. (2011). Beyond bottom-up processing. In Cognitive psychology: Mind, research and everyday experience (3rd ed., pp. 52-56). Belmont, CA: Wadsworth Cengage Learning.

Hollow face optical illusion – visualfunhouse.com. (2008, March 29). YouTube. Retrieved February 2, 2014, from http://www.youtube.com/watch?v=OHuStlT1RM8

Kubie, J. (2013, July 28). Depth Perception and the Hollow Face Illusion. Retrieved February 1, 2014, from http://blog.brainfacts.org/2013/07/depth-perception-and-the-hollow-face-illusion/#.Uu9LnvuorzO

Demon Hill - Science Friday

Demon Hill: Perceptual Conflicts

Optical illusions have always been intriguing to me so, this week’s lesson on perception was really fascinating.  As I was reading all of these images of optical illusions I had seen before were popping into my head.  I realized I could apply what I now know about the way neurons deliver perception to just about every optical illusion I’ve ever seen.  For an optical illusion to work it needs to trick the mind into experiencing something that isn’t there or not experiencing something that is there.

I scoured the Internet for a reputable source that would demonstrate a difference between perception and reality.  I kept finding photos of sidewalk art.  They were impressive but they only twisted our perception in two dimensions.  During several rounds of searches I kept seeing a YouTube video of an illusion that worked in three dimensions (Science Friday, 2012).

Step Into an Optical Illusion

The illusion, called Demon Hill, is a room that is canted on two different axes.  It’s designed to put a person’s senses at odds with what they know to be true about the room.  I’m still trying to wrap my own brain around the way top-down and bottom-up processing work together.  But, what I think is happening to people who visit the room experience is that they are experiencing conflict between several bottom-up processes and then a conflicting top-down process is thrown in for good measure.

If you were to stand in this room, your physiology would send sensory data to your brain about your surroundings. Your sense of equilibrium would tell you that the room is tilted but your visual [bottom-up (Goldstein, 2011)] and experience with normal rooms [top-down (Goldstein, 2011)] would tell you that the floor of the room has to be parallel with the ground.  We can see this expectation most clearly when the subject in the video tries to pour water into a glass.  He expects that the pull of gravity will be perpendicular to the floor of the room despite his knowledge that the room is canted.

The more I study psychology, the more it changes the way I look at the world.  I tend to think much more about what I’m experiencing and how other people are behaving.  I know that because of this lesson alone I will be much more aware of differences in what I’m perceiving and reality.

Bibliography

Goldstein, B. E. (2011). Cognitive Psychology (Third Edition ed.). Belmont, CA, USA: Wadsworth.

Science Friday. (2012, October 12). Step Into an Optical Illusion. Retrieved January 29, 2014, from SciFri Channel on YouTube.com: http://youtu.be/1BMSYXK4-AI

Science Friday. (2012, October 12). Step Into an Optical Illusion. Image retrieved January 29, 2014, from ScienceFriday.com: http://www.sciencefriday.com/video/10/12/2012/step-into-an-optical-illusion.html

How Fear Alters Perception

How Fear Alters Perception

I found the topic of perception the most interesting out of the topics that had been discussed thus far, but I was interested in knowing how the accuracy or normality of our perception can change depending on the stimuli.  I went to reddit.com/r/psychology and searched for articles on perception.  An interesting articles that appeared in the results was “Phobias alter perception, German researchers say.”

In our lesson on perception, we learned of bottom-up processing and top-down processing.  In bottom-up processing we are taking in stimuli from the environment in the form of environmental energy through our sense organs.  Our sense organs then transform this environmental energy into action potential.  This action potential is sent to our brains where it is processed.  In top-down processing, we gain information from our experiences, knowledge, and expectations.  This information is used to help process the external stimuli.  With these processes combined, our brain can smoothly process both internal and external stimuli to help us understand and interact with the world.

The article I read was a summary of findings from a study that considered the individual differences of human perception.  The control group had no phobias and the test group suffered from arachnophobia.  The researchers found that phobia-related stimuli can alter the way that the brain processes vision (Osterath, 2014). This is significant because it helps to demonstrate what is occurring in the brain of someone with a phobia, which can further influence how treatment for their phobia is developed and applied.  One of the tests (and the one that specifically relates to these findings) that the psychologists performed was a test that showed two pictures at the same time.  According to the researchers, the brain cannot see two different pictures at the same time (Osterath, 2014).  Essentially, this means that we (subconsciously) make a decision on which picture to process first.  In the test, one of two pictures was a series of colored triangles; the other image was either a spider or a flower, alternating.  The test subjects pressed a button on which image they saw on the screen.

The researchers found that the Arachnophobe group processed the image of the spider almost twice as often as those in the control group (Osterath, 2014).  With these results, the researchers can hypothesize that fear and emotion play a large role in what stimuli the brain chooses to perceive.  The researchers believe that the amygdalae may be directly connected to the brain’s visual processing center.  This would mean that your brain will not let you miss something that you are afraid of, probably an evolutionary defense mechanism that went awry in the brains of those suffering from phobias (Osterath, 2014).  Researchers have yet to confirm this connection; this is speculation.

The results of this study can be a tool in understanding our lesson on perception.  Not only do we use bottom-up processing, but we use top-down processing.  So, while our brain is perceiving this image of a spider, it is using top-down processing to connect the spider with feelings and emotions of fear and distress.  Our brain knows we are afraid of it, and can use this top-down processing to communicate this with the body and let the body take the next steps (fight or flight).  With these findings, another door is opened in the research field of cognitive psychology and neuroscience.  We can hope that next someone will study the link between the amygdalae and the brain’s perception centers.  One of the most common mental health disorders is a phobia.  With more research concentrated on the things we are afraid of are perceived in the brain, we can help improve daily life with those who suffer from this disorder.

 

References

 

Osterath, B. (2014, January 09). Phobias alter perception, German researchers say. Retrieved from http://www.dw.de/phobias-alter-perception-german-researchers-say/a-17345676?maca=en-rss-en-all-1573-rdf