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Week 7--Interpreting Ambiguity

Anne Dalke's picture

What were your reactions to the story Paul Grobstein told in class today, that "incoming information is always ambiguous, and subject to multiple interpretations"? That, in a world in constant flux, our brains "locate and give meaning to randomness," by relying on "the presumption that things don't change a lot over time"?

What ambiguous figures/optical illusions/magic tricks/blindspots can you use, and what survey can you design to test out and extend your reactions to this story?

Post both the data you've gathered and your interpretation of it here, by 5 p.m. on Friday.

jfahl's picture

Ambigious Figures


Ambiguous Figures: Question 1: How many images did you see?       Question 2: How many images did you see?      Question 3: Did it affect your perception of the image knowing that it was an optical illusion?      The control group, Group B, which knew it was an optical illusion from the start disagreed that it affected the way that they viewed the picture. However in Group A only one person saw more than one image in the picture. I think that this makes an interesting case for what we think we know. The group that knew the image was an optical illusion considered it to be common knowledge. I didn’t know what the data was going to prove to me before I gave the survey. On one hand this means that I didn’t bend the data to any side. But I also didn’t know what the point of my study was. Ulitimately I found that the hubris of the average college student blinds them from truths. Take for example Group B. There is nothing different about Group B other than they were told ahead of time what the image was. But the data shows that group B overwhelmingly believe that their knowledge didn’t change their perceptions.Ambiguous Figures: Question 1: How many images did you see? Question 2: How many images did you see? Question 3: Did it affect your perception of the image knowing that it was an optical illusion? The control group, Group B, which knew it was an optical illusion from the start disagreed that it affected the way that they viewed the picture. However in Group A only one person saw more than one image in the picture. I think that this makes an interesting case for what we think we know. The group that knew the image was an optical illusion considered it to be common knowledge. I didn’t know what the data was going to prove to me before I gave the survey. On one hand this means that I didn’t bend the data to any side. But I also didn’t know what the point of my study was. Ulitimately I found that the hubris of the average college student blinds them from truths. Take for example Group B. There is nothing different about Group B other than they were told ahead of time what the image was. But the data shows that group B overwhelmingly believe that their knowledge didn’t change their perceptions.
pbrodfue's picture

Eliza's data

Pop Art Quiz

*Below are the results of 15 participants.

1. Out of the six questions, how many questions did you get right?

Correct answers

Number of people














2. Did you expect to get that many questions right or wrong?

No expectations

Expect to get more wrong

Same as expected

Expect to get more right






3. Did you have a strategy?






Strategies given by each participant:

1. tried to remember as much as she could

2. defocused eyes to see general picture

3. got an overall idea by looking at the rows

4. looked at the thing as a whole to see if anything flickered

5. stared at the screen, then at the big picture

6. looked all over page

7. circled around the page, whatever she just happened to be looking at

8. looking at the white squares


4. Did you think that you effectively or ineffectively processed the information presented?



Neither effective nor ineffective









Among the 15 people, the questions answered correctly were split fairly evenly between two, three, four, and five. As a result, no common trend existed in the number of questions that they got right or wrong.

My objectives in the following questions were as follows. In question 2, I wanted to see how people first approached the artwork and their task when it was originally presented. Would this be an easy activity (scoring right answers) or would it present a challenge (scoring poorly?) In question 3, my goal was to see how the participants actually went about completing the quiz and lastly, their ability to process the information they saw.

My data was split when it came to expectations, strategy, and effectiveness at processing information. However, not finding a common conclusion was significant. Before questioning anyone, I thought that all people would do relatively poorly. I did not expect to see such contrasts in the data, but it did show that each person truly dealt differently with the information. Interestingly, six out of the eight strategies included pertained to an overall, general picture of the artwork. From this, two points stand out. With so many boxes and colors, it was almost impossible to notice the details. It was necessary to look at the figure as a whole. Also, despite similar strategies presented, the number of correct answers widely varied. Just as Paul Groebstein mentioned, no brain is the same. Each brain has its inherent differences.



pbrodfue's picture

Marisa's data

Interpreting Ambiguous Figures: Omvivore’s Dilemma

Interpreting Ambiguous Figures: Omvivore’s Dilemma

Image 1Image 1 Image 2Image 2


Question Number


Yes Answers

No Answers

Question I

Do the horizontal lines appear parallel in image 1?



Question 2

Do the horizontal lines appear parallel in Image 2?



Question 3

In Image 2, does the starburst pattern effect your perception of horizotal lines?



Percentage Q1



Percentage Q2



Percentage Q3



Question Four: How does the starburst effect the perception of the horizontal lines in

Image 2? Most people said something along the lines of, “It makes the

middle lines appear to buldge outward slightly” or, “It makes the middle

buldge.” One person said “They’re actually parallel.” Two people didn’t

answer and a few had trouble seeing the curvature of the lines.

Question Five: What does this say about how peoples’ brains percieve the external

world? Most people came to the conclusion that our brain can

misinterpret reality and that we are easily influenced. Two people

neglected to answer because they weren’t sure.


The optical illusiion in image 2 teaches us that the brain is inclined to make guesses about the future. Thus, in the starburst pattern the viewer feels pulled towards the middle of the pattern. The brain expects us to walk up closer to the image and thus shows us ahead of time the middle getting bigger. Our brain assumes that our relation to stationary objects will change over time in predictable ways but this is not always the case. Most of the time it is advantageous to anticipate what we will see a little into the future but sometimes it can be more useful to see what is infront of us now.

lwacker's picture

 It was very difficult for

 It was very difficult for me to find a proper sample size for data intake

 but I polled sevenwoman and skull girls from Rock 2nd 2nd when looking at the very first optical illusion we studied with Paul Grobstein.

First, I asked the ladies whether or not they saw a woman in the picture. They could respond with a yes or no answer. All of my questionees saw the women in the image.


Then, I asked them whether or not they saw a skull. Yes or no. All of my questionees saw the skull in the image.


Lastly, I asked how many distinctly separate images they saw within in the picture.  I had them count for this question and it was here that I had the most interesting responses. Six girls, all but one test subject, thought that there were two separate women in the image. Only one girl realized that it was a reflection of the first woman in the mirror. Additionally, none of the girls saw curtains in the nose of the skull as Paul explained last Tuesday in class. When I explained to the girls that the skull might not exist but be entirely a creation of their brain they were astounded and quite confused but understood the concept almost entirely after further explanation.


Shoshi's picture

Ambigious figures

Ambigious figuresAmbigious figures
stephkim's picture

Proof   1 2 3








akaltwasse's picture

Just noting that, for the

Just noting that, for the second time, Serendip has logged me out and returned me to the home page after clicking "preview comment."  Has this happened to anyone else?

 For my survey, I asked residents of Rockefeller 1st-1st and 1st-2nd to answer three questions using this image:

1.) Which of the three soldiers looks the tallest?

All six subjects answered that the soldier on the right looks the tallest, which did not surprise me because that was my first impression (and the reason I made it the first question).

2.) Briefly explain your answer.

Although all six subjects said something different, all of them mentioned perspective, the spacing between the lines, the direction of the lines, and the angle at which each soldier stands.  These results did not surprise me, either, because it is clear from how the lines slant that there is an impression that there's a vanishing point and that the third soldier is placed towards that vanishing point, when he's really just placed the highest in the image.

3.) "All three are the same height."  Do you agree with this statement?"

Five of the subjects circled "yes" and one wrote in "maybe" (yes and no were the only choices I gave).  I am curious to know what makes that subject unsure, since you can easily measure each soldier or even remove the lines from the drawing.  But I do see how she could be uncertain without measuring, because, even though I know they're all the same height, I can't quite get my eyes to see that, too.

eolecki's picture

Pop Art Quiz!

I used the pop art quiz from the New York Times article as the subject of my survey.  The quiz shows a picture of many different colored squares.  It then gave the participant 3 seconds to look at the picture and then highlighted one of the squares.  When the square was highlighted it could either change colors or stay the same.  People were very surprised how hard it was to tell if the square changed colors.  I recorded everyone’s score and then asked them a series of questions. 


What was your score?    /6


Did you find it difficult to tell if the color was changing? Yes No


Why do you think you could or couldn’t tell if the color was changing?  What do you think you were you focusing on, the entire picture or individual squares?


I gave them the following excerpt from the article “Blind to Change, Even as It Stares Us in the Face” from the New York Times and had them answer the last question 
Visual attentiveness is born of limited resources. The basic problem is that far more information lands on your eyes than you can possibly analyze and still end up with a reasonable sized brain. Hence, the brain has evolved mechanisms for combating data overload, allowing large rivers of data to pass along optical and cortical corridors almost entirely unassimilated, and peeling off selected data for a close, careful view. In deciding what to focus on, the brain essentially shines a spotlight from place to place, a rapid, sweeping search that takes in maybe 30 or 40 objects per second, the survey accompanied by a multitude of body movements of which we are barely aware: the darting of the eyes, the constant tiny twists of the torso and neck. We scan and sweep until something sticks out and brings our bouncing cones to a halt.  So as you scanned the picture you did not take in the color of the individual square until it was highlighted and at that point you did not know what color the box was before, so when it was highlighted the individual square was recognized by your brain and appeared to change color. Experiments strongly suggest that the visual system can focus on only one or very few objects at a time, and that anything lying outside a given moment’s cone of interest gets short shrift. The brain, it seems, is a master at filling gaps and making do, of compiling a cohesive portrait of reality based on a flickering view.

Our spotlight of attention is grabbing objects at such a fast rate that introspectively it feels like you’re recognizing many things at once. “But the reality is that you are only accurately representing the state of one or a few objects at any given moment.” As for the rest of our visual experience, he said, it has been aptly called “a grand illusion.”


Do you think this is a reasonable explanation, why or why not?


The average score was 3.4, with the lowest score being a 2/6 and the highest a 5/6.  On average people got a little more than half of the questions right.  Everyone except one person (who got 5/6) said that they thought it was hard to tell if the color was changing or not.

I got a variety of responses for what method they used to try and see the boxes.  One person said they just focused on the black and white, that the entire picture looked different if the box changed, that she could only tell if she had just looked at the square that had changed and for most people the problem arose from trying to focus on too many squares at the same time while trying to remember the color of the square.

Everyone except for two of the fifteen found the story given in the article to be reasonable.  People who believed the articles came up with response that applied to their daily lives like not focusing on certain things or not picking up on detail.  There was also responses that said they believed it because the Pop Art Quiz supported it because they weren’t focusing on it until the squares were highlighted because there was just too much to look at.  The negative responses said that it was just guessing and chance and certain colors stuck out while others didn’t.  The second non-believer said that their brain viewed the picture as one image, not individual squares so they didn’t think the article was correct.

From collecting this data and taking the test myself, I found that I believe this information even more.  Once people were exposed to this theory they could think about their daily life and see lots of examples that support this theory.  It was very interesting to see people’s responses after the first trial because they were so surprised how hard it was to tell if the square had changed.  There is a moment of unsettled, was it there before?  It just seemed to appear out of nowhere.  A lot of people just guessed for a lot of them so the average score is a little inflated by lucky guessing.  I think the reason so many people believed the article because it was a logical argument and they had no alternative idea to dispute it.  I think this survey showed that people are willing to accept the first logical argument that comes along when there is something they don’t understand.  Most of the people who I surveyed tried to connect their original answer with the article.  
mkmerrill's picture

I did my survey on peoples

I did my survey on peoples reaction (the volleyball team) to the skull image. I wanted to see if there was a trend in what they saw. In other words I wanted to see what interpretation of the ambiguous figure the brain prefered, or if it even prefered one over the other.

I gave each player an image of the ambiguous figure and asked them four questions about it:

1. How many images do you see? and what are they?

2. What image did u see first?

3. What image did you like better?

4. Why do you think your brain chose the image you saw first?

Everyone saw two images (one person saw a woman playing chess). Everyone agreed that the first image they saw was the skull, and majority said they preferred the image of the lady in the mirror. Overall, they thought that the reason they saw the skull first was because it was the dominant image, in addition to being a white image surrounded by black.

It turns out that although the individuals preferred the softer image (more feminie-> all girls) the brain selected the other image. I interpreted this information as follows: the persons personal preference doesn't impact the choice of the brain. The brain chooses based on what is seen first; the dominant image. I wouldn't say that the brain has a preference as in it "likes" one image over the other, but it does "prefer" images more easily detectable.

Shoshi's picture

Ambigious figures

I did my survey on people’s reactions to an ambigious image of a woman and a skull. The picture was a black and white drawing of a woman sitting at a vanity table and staring into a mirror, or, if you see it another way, it is a picture of a giant skull. I noticed that when this picture was shown in class, many people had very different reactions to it. I, personally, could not see the woman in the picture until it was pointed out to me, yet there was another girl who was the complete opposite and could not see the skull. So I asked fifteen random people in dorm to look at the picture and tell me what they saw first, whether they could see the second picture without bring told it was there, how long it took them to be able to see the second picture, what caused them to see the second picture, and how they feel about being able to see both pictures. I choose these questions because of the diversity with which our CSEM class responded to this and other ambiguious figures in class. In class, not only did people see each picture differently, showing the different ways with which all of our brains view the world, but some people also objected to seeing these different images. They objected to seeing these images because in order to see both images you have to change the way your brain views the world. Therefore, I went into the survey expecting very diverse results, based not only on what I had esperienced firsthand in CSEM, but because I knew all of these people personally and they were all raised in completely different environments and all have very different opinions about the world. I was therefore beyond surprised as I went around to everyone individually and got almost identical answers from everyone. Everyone I showed the image too saw the skull first, then almost immediately, without being told saw the second image of the woman. Excepting two people who needed to be told about the secondimage. They all noticed the image fairly quickly and most for similar reasons, such as moving away from the object or as simple as taking a second lokk at the picture. I also was surprised by how everyone said that they were ok with being asked to change the way their brain works in order to see both images. At first I was surprised by these responses, but then one of the people I surveyed said the reason she liked the ambigious picture was that she liked having her views of the world changed and challenged. So, I thought that viewed in this sense, my results for that question made sense, Bryn Mawr is a place of open-minded women who are at the college for the purpose of being exposed to newideas, opinions, and experiences. This conclusion made the fact that everyone I asked could see both images without prompting and that they enjoyed the images, because they are open minded intellectuals who all view the world differently but areopen enough to view it multiple ways at the same time. But this only made me curious about why everyone saw the skull before the woman. Everyone could see both, so why the skull first? I thought maybe it was the simple solution that the skull was the bigger image and all white so it is much more striking, but I could not help thinking of the girl in class who could not see the skull. So, I thought maybeb it has something to do with what the image actually is. The skull is a picture that can inspire fear in many because it reminds us of our mortality and that the same fate awaits us all and the iamge of the woman was one of beauty. I believe this also has a lot to do with the student body woith Bryn Mawr. Even though I have only been here for a limited time I have found that not only are people here opneminded, they are not superficial. I have found that the average student at Bryn Mawr is more likely to have a conversation about religion and the meaning of life then about celebrities and what the new fall fashions are. We are all much more focused on our mortality, on worrying or learning about things that are more important for us to learn in our short time here, rather than on appearances, which are fleeting, and being superficial. Keeping this in mind, it made much more sense that everyone saw the skull first.
yhongo's picture

mans' face and woman

The picture I used for the survey was the one with the man's face as one figure and a woman in a winter coat over with her back showing, standing by a tree. I asked 15 people in my hall to explain to me what is happening in the picture. 8 people said that saw a lady in a fur coat standing by a tree first. Afterwards, they saw the man's face. 5 people said that they saw the face first, and the woman second. 1 person said, "well I see two things: a man's face and the back of a woman". 1 person said that they only saw a woman in a fur coat and nothing else.

It was interesting to see that people either saw the man's face first or the woman first. It was even more interesting that to some people, they can only see one image and nothing else. 

A factor that could have affected the results is the distance the person held the paper with the picture on it. I saw that if the person held the paper far away, they saw the man's face first. However, if they brought the paper close to their face and studied it very closely, they saw the woman first.  

ihe's picture

I surveyed 15 students


I surveyed 15 students about this optical illusion, asking the following questions:

1. Is the corner with teh dot towards you or away from you?

2. can you see the box fro the other point of view

3. Are you able to interchange the two points of views quickly?

4. Stare it it from one point of view for 10 seconds. Is it harder now to switch between teh two points of view?

5.How hard was it  for you to focus on one point of view on a scale of 1 to 5. 1 :easy, 5: hard

6. how hard was it for you to interchange views on a scale of 1 to 5. 1: easy 5: hard.

80% of the people I surveyed, saw the corner as away from them. Therefore they were seeing the top of the box.  The majority of the people saw the box as under them, therefore seeing the top of the box (dot away from them), becuase they are used to seeing boxes below their eyesight, and therefore having developed a mental image of a box. 87% of them said that they could see the dot coming towards them also, meaning they could see the box from bottom up. Their brain could process it and rotate the box around in there head. Many of them found that after staring at the box from one point of view for a period of time, in this case, ten seconds, it was harder for them to interchange the way they saw the box.I also found that there wasan inverse relationship between how hard it was for them to focus on one point of view and how hard it was for them to interchange the points of views. Many people who had a hard time switching view pointsquickly in the beginning, found it harder to switch the view points after staring at it for 10 seconds.


cantaloupe's picture



I asked seventeen people to look at the optical illusion and answer the five questions represented in the graphs. I was mostly interested in how people felt in regards to optical illusions: my last graph. However, I started off by asking people what they first saw. I was suprised that more than half of the people saw the person walking first because I see the face first. I realize that how close or how big the image is greatly affects what image one sees first. I first saw the image on the computer full size, which made the face more apparent. There was a discrepency in the results between question three and four because one person answered that she could not see both images, but every respondent answered that they could voluntarily switch between the face and the person walking. The results to the last question were the most interesting. I find optical illusions very frustrating, but most people responded that they find them fascinating. One of the reasons the results to this question might have turned out this way is because the majority of the respondents could see both images and switch between both images, which makes it less frustrating. If the respondent group had a harder time seeing both images, more of them would have been frustrated.

mmg's picture

Optical illusions


A skull or two ladies?

The pciture used for the survey


The questions I asked in the survey were: 

1. What do you see in this picture?

2. Do you see anything else in this picture?



3. If yes, what do you see?

4. Was it easy for you to see the second image, or did you have to concentrate really hard to see it?

It was easy
I saw both at the same time!
I had to concentrate really hard to see the other image
I could see only one image


The results I collected are displayed in these graphs: 

Graph showing the responses to the two images

Graph showing the responses to the two images


Level of difficulty in viewing the images

Level of difficulty in viewing the images

Most people saw the skull first because it is a bigger whole than the lady. The image of the two ladies is one that is more detailed and hence can be brought to focus by looking at the picture in detail. Thus I found that the brain looks at the whole or bigger picture first. Thus the ‘top down’ method of perception was at work here.

I also found that two people who were not able to see the other image – that of the two ladies incorrectly assumed a second one because of the way the questions were phrased. Even though the second question of my survey enabled people to say that they did not see a second image, because the following question was about the second image, they assumed that there was definitely a second image and worked at developing it. Thus the brain took cues from the environment and made an estimated guess.

Most people however found it easy to see both the images in the illusion. Half of them saw both the pictures at the same time. Yet they chose to report the skull first because of the reasons already discussed.

This made me realise that our brain often takes the liberty of interpreting things for us and chooses the most obvious answer first.

hwiencek's picture

Does Context Affect Meaning Perceived?

After the class with Paul Grobstein the other day I was left wondering if our brains locate and give meaning to randomness does context affect the meaning we perceive?  I used the images below to test this.

Picture 1Picture 1

Picture 2Picture 2

There are two images hidden in each picture.  The middle color block can be seen as a goblet/candlestick/vase and the outer color block can be seen as two profile faces. 

I gave half of my participants Picture 1 and half Picture 2 and asked the following questions:

1) Look at the figure below for 1 second (basically aglance).

2) What do you see?

3) Look at the figure below again for 10 seconds.

4) What do you see?

I was hoping to see that the background (the context) would affect a person's ability to see both images.  I hypothesized that more people would be able to see both  images in Picture 2 because the outer blue border calls more attention to there being two images, whereas in Picture 1 the image of the profile faces is lost into the white of the background.


However, I found that the background didn't actually made a difference.  Of the twelve people that I surveyed (six with each picture) all six people saw both images in Picture 1 and five people saw both images in Picture 2.  (Interestingly, the person who did not see both images in Picture 2 only saw the goblet/candlestick/vase image.)  While this information does support my hypothesis, five of the six still saw both images.  So, from my results I would say that context does not affect the meaning perceived from an image.



However, that being said, my sample size was excessively small and many of the people who I surveyed had already seen this picture before in some form or another and already knew about the two images, which most likely greatly affected my results.  I would like to repeat this on a larger scale and with a similar, yet lesser known picture.


nmackow's picture

Color Perception Study.

I questioned 16 Bryn Mawr students about the following two pictures:


For the first illusion, I asked whether the image appeared to be moving to the subjects. Only 25% of my subjects responded Yes. I think that because participants knew they were expected to be tricked by the illusion, they were determined not to be. I then asked what color the spirals in the picture appeared to be. It seemed that most people could only see that there was a yellow spiral, which makes me think that my question caused subjects to look too closely at the image. It is true that the main spirals are yellow, but at first glance the inner spiral should appear to be a cream or pinkish color. Here are the results of that question:

The next questions I asked pertained to the second image I have displayed. I asked subjects to read out the color of the word they were seeing and not the actual word. Because one part of the brain recognizes the word it is seeing and another part tries to identify the color presented, errors of perception can occur. This can cause people to read out the actual word instead of the color they are seeing. Here are my results:

I asked respondents if the reasoning for this perception error made sense. I wanted to know if people knew why it was hard to vocalize the color of a word when the word was a color before they took my test. As you can see, it appears that a majority of respondents knew this fact before taking the illusion test which may have skewed responses.




emily's picture

Gorilla Graphs

After reading the article in from the nature journal about magic tricks, I was reminded of the experiment (because it was mentioned) on unintentional blindness where people are supposed to count the number of passes a certain team makes and will not notice that a big gorilla walks through the scene because they are focusing so much on counting. I decided to send that video to people ( along with my survey about it and told them the following:

"Please watch the following video clip.

this is a video clip of two different teams passing a basketball around.

focus VERY CAREFULLY on how many passes the team in the black shirts makes and make sure to count the passes.
the following survey will ask you how many passes they make along with a few other questions."

The survey asked 5 questions. question 1 asked the participant to state how many passes the team he or she was watching made. The second asked if they noticed the gorilla that walked through the middle of the players (yes, no). The third asked "If yes, have you seen this video before?" (Yes, No, I did not see the gorilla). Question four asked "If yes but you have not seen this video before, did you accurately count the number of passes made?" (Yes, No, I have already seen this video, I did not see the gorilla). Question five asked the participant, if they did not see the gorilla, to watch it again and rate how surprised they were to have not seen it at first (Not surprised, somewhat surprised, very surprised, utterly speechless, I have already seen this video, I did not see the gorilla). 

After 10 people had taken it, and every single person had seen the gorilla (when we did it in my psych class last year, only another girl and me saw the gorilla because we were not paying attention to counting...everybody else missed it!), I realized that something was wrong with the way I was conducting my experiment. I decided to send out my survey again, only this time asking the new participants to count the passes made by the team in the white shirts, not the black shirts as before. I was wondering if the black gorilla was getting caught by people's eyes who were watching the black shirts. However, everyone there too saw the gorilla. I have concluded that the way which this video was presented, online in an email, greatly inhibited my results. If I were telling the participants in person to really focus on the passes made, I could make my voice sound really important and probably make them focus more, as my psych teacher did to my class. However, the fact that the video was presented so impersonally made people not focus that much on the counting. This is shown in my graphs:

The first graph just shows that almost everyone saw the gorilla, except for one person counting the black shirts. The second graph just shows what percent of those who saw the gorilla had not seen the video before, because once you see the video once you are sure to see the gorilla the second time you watch it because you will not be concentrating on the passes as hard or you will know the gorilla is there. The third graph, however, is the most interesting to me. This shows that the majority of the people who had not seen the video already did not count the passes accurately. This shows that they were not focusing extremely hard and therefore probably noticed the gorilla (the person who did not see the gorilla left question 3 and 4 blank for some reason, so they are not represented on those graphs). My last graph just shows that the person who did not see the gorilla was "very surprised" that he or she did not see it. 

aybala50's picture

If the brain takes offense does it hate the offender?

I really enjoyed our discussion in class about how weperceive the world as humans. I think that the idea that humans see the worldthe way they want to see it, not necessarily how it really is. In my opinion itmakes sense that the brain would give sense to things in this world that don’tmake sense otherwise. This could almost be considered a defense mechanism. Ifthe world around us is truly full of randomness and change, the human mind maynot be able to handle this. It is possible that humans are created to adjust toa certain world and continue growth through studies etc. If the constant changein the world distracted humans from this process we may have never evolved intowhat we are today. Also I don’t think that the human mind could handle thestress that would come along with constant shock caused by the constant changesin the world surrounding us. This is why I wanted to see, with the use of anoptical illusion picture, whether the fact that a picture fools or doesn’t foola person’s brain affects if they like optical illusions or not. 

I used this image of a young woman and an old woman: 




I asked 5 different questions to see which image a person sees or if they see both images. THen I asked whether they liked optical illusions. The results I came up with for which image is seen is shown in the graph below:



After figuring out how many people saw which image I wanted to see if there was a correlation between which image(s) was seen and if the person liked optical illusions.

 Person                     Which Image Was Seen Yes/No

1 Both Yes

2 Both Yes

3 Both Yes

4 Both Yes

5 Old Woman No

6 Both Yes

7 Both No

8 Old Woman Yes

9 Young Woman No

10 Both Yes

11 Both No

12 Both Yes

13 Young Woman No

14 Both Yes

15 Old Woman Yes 



I believe that this survey wasn't very conclusive, or at least only a week correlational study. Most of the subjects that could see both images reported that they like optical illusions (8 out of 10). Some of the subjects who were only able to see one of the images in the picture reported that they don't enjoy optical illusions, while the others reported that they did (3/2). 

There could be a weak correlation here, but I couldn't say whether this was true or not. The results are not strong enough for me to say so, but I think that if I had given the survey to more than 15 subjects, my results may have been more conclusive.

So, I can't really use this correlational study to say whether humans who's brain are tricked dislike optical illusions, or to say whether humans who manage to solve an optical illusion enjoy optical illusions.  

Serendip Visitor's picture

i cant find the old woman in

i cant find the old woman in the picture.

Serendip Visitor's picture

To see the old woman

The old woman nose is the young woman face. Her eye is the young woman ear and her mouth is the young woman ribon in the neck.

aybala50's picture






kscire's picture

Panda Optical Illusion

Panda Image


Question 1Question 2Question 3Q4Q5

I Surveyed 15 people about the panda image and all fifteen participants reported seeing atleast two pandas. All of the participants saw the two full-sized black and white pandas in the image and 13/15 participants recognized that there are more than the two obvious pandas in the image, wether they are in the rocks or in the bamboo. The questions were asked after seeing the image for only a minute and I would be curious if that after looking over the image longer if there would be a higher number of participants reporting 2+ pandas. Also, I did not present this image as an "optical illusion". I would suspect that all fifteen participants would have said they saw more than two pandas if I had presented the image as an illusion. 

lraphael's picture


Which way do you think the cheetah on the left is facing?Which way do you think the cheetah on the right is facing?Do you think the cheetahs can be facing both ways?

I asked people 3 questions about this image:


The graph about the cheetah on the left had 17 people say that the cheetah is facing backwards and 9 people say that the cheetah is facing forwards.

The graph about the cheetah on the right had 18 people say that the cheetah is facing backwards and 8 people say that the cheetah is facing forwards.

The graph about if the people thought the cheetahs could go both ways had 23 people say yes and 6 people say no.

What I was trying to prove was that the picture is not only ambigious, but it all depends on a personal view. I only had the people look at the graph for 10 seconds and answer each question. The interesting part was that even though people said they could go both ways, only one person answered that both cheetahs were facing fowards. The point of my survey was to make people decide which direction the cheetahs were facing, and to see if there was more of a trend. I wanted to see what way the majority of people though the cheetah was facing, I thought it was going to be 50/50 but it wasn't so maybe next time instead of asking on I will ask in person which they think to make sure that they only look at the survey for 10 seconds at a time.


mcchen's picture

Checkerboard Optical Illusion: Is Square A darker than Square B?

Question 1:        Question 1. Does this look like an Optical Illusion?

Question 1:  Does this look like an Optical Illusion?

Question 2: Is Square A darker than Square ?

Question 2: Is Square A darker than Square B?

Question 3: Do you believe what I have just showed you?

Question 3: Do you believe what I have just showed you?

Question 4: Are you compelled to try it for yourself to see  if it’s true?

Question 4: Are you compelled to try it for yourself to see if it’s true?

Question 5: What do you think causes us to think Square A is darker than  Square B?                  our brain,  our eyes, the shadow in the picture, or all of the above 

Question 5: What do you think causes us to think Square A is darker than Square B? our brain, our eyes, the shadow in the picture, or all of the above 

By asking the survey participants if they thought this was an optical illusion, it gave me a sense of whether or not people were expecting to be tricked.  Of the 5 People that did not believe this optical illusion after I showed them the reality, they had also thought it was not an optical illusion to begin with.  This leads me to wonder how some people can completely dismiss what their eyes are obviously seeing.  If they were not expecting to be tricked in the first place, I was expecting them to be more open to whatever “picture” I presented to them.  Two participants were even unwilling to “try it out” for themselves even after they thought my claim was not believable. If I have the notion that I am being tricked, I will attempt to look at a problem from all angles before coming up with a solution.  And usually if I don’t believe something I try it out for myself (hence the optical illusion I chose since I did not believe it when Paul showed us in class).  By asking question 5 I was attempting to gauge if people knew what was doing the “tricking” when it comes to optical illusion.  I found that only 2 out of 15 people know that your brain is the one “tricks” you into interpreting differently than your eyes are seeing. 

jpfeiffer's picture

Optical illusions

For the optical illusion survey, I used the very popular picture of the two faces and the vase to collect results on what was seen, and a possible explanation for what was seen. I showed it to several people on my floor, and in my Spanish class, and the results varied rather greatly from person to person. I decided to pick a rather popular image to use in this survey because prior to our class discussion I had not really considered what was happening behind the image to create an optical allusion. However, after learning more about optical illusions I thought it would be interesting to collect the opinions of other people with respect to the image.

The results that I collected showed that the image that was seen first varied greatly amongst the people that I asked. For example, while most of the people said that they saw the two people looking “face-to face at one another”, some first saw the vase, and one of the participants first saw a goblet.

I asked the participants if the original image that they saw was vague or definite and I found it interesting that all of the participants responded that the image that they saw was definite. I also asked if they saw more than one image in the photo, however, and all of the participants answered yes.

Lastly, I asked the participants if they could elaborate on their reasoning, if any behind what they saw, or if they could give a description of what they saw and how they went about seeing it. Some people responded that they felt like their eyes were sliding out of focus when they tried to see both of the images.I researched this at this is called multistability or literally multiple perception. Other people said that what they saw was just immediate and there was no reasoning, at least not apparent to them, for why they saw what they saw. Finally, some people responded that they saw the people or the vase first, then, after focusing, were able to see the faces of the two people.

msmith07's picture

The Magic Trick!

I performed a (fairly unimpressive, if I do say so myself) magic trick for girls on my floor at a hall tea tonight. The trick begins when I present someone from my audience a rope, and I ask her to tie the rope into a simple knot. Then I ask her to do the same thing, but while holding both ends of the rope and not letting go. I’ll allow several audience members to try this, and generally no one is able to accomplish the task, however they may try. Then I take the rope and, through magic obviously, am able to tie the rope into a knot without ever letting go! It’s magic. Ooooooooh…

Reactions to my Magic Trick

I performed for, conveniently enough, 15 girls, in small groups. After each performance, I asked each group the same question, roughly, and recorded the answers:

7 people said they focused on the rope
4 people said they focused on my hands, in general
3 people said they focused on my left arm
1 person said she focused on my right hand

Only one person said she thought she knew how I did the trick; the rest claimed to have “no idea”.

When they attempted it themselves, no one was able to do the trick. 6 people out of the 15 tried, and I asked them to try before I performed the trick.

I asked all of my audiences what they thought the trick was based on, and some people said that they were distracted by me talking (I chatted about summer camp while I performed the trick). One girl mentioned that the rope was black, and so was my shirt, and it was difficult to see what was happening.

I should also note that on two occasions, I messed up the trick the first time and the audience was nice enough to let me try again. Both times, people still did not discover my trick.

My Results

I think the most important aspect of my trick was that I distracted the audience by talking during my trick. One article in our reading mentions the pickpocket performer bantering with his audience victim while simultaneously stealing his wallet and watch. While my rope-tying adventures were not nearly as lucrative, I did use the same trick of casual banter to distract. Also, the visual limitations of not being able to watch all of the areas of the rope at once (I tie the knot with a grandiose gesture) enabled the slight of hand needed to perform the trick successfully.
abhattacha's picture


Though the degree of ambiguity differs , every input to the brain can , and is , interpreted in more than one way by different individuals . These are the informed best guesses of each brain of what is out there that is meaningful to itself .
The fifteen randomly selected subjects under study were shown Figure 1 ( /exchange/ambigfig/gilbert ) . The overwhelming majority ( 13 out of 15 respondents or 87% ) identified the figure as that of a skull . When probed about what led to their answer , they typically identified the white expanse of the forehead , cheekbones and jaw . Only two respondents ( 13% ) said that the picture depicted two women , framed by a porthole / round window , sitting across each other at a formal dinner .
When exposed to Figure 2 ( /exchange/ambidfig/cheetahs )  , every respondent saw two leopards , one standing , and the other seated .
Working on the hypothesis that the sharp contrast in Figure 1 and the largely uniform tone of Figure 2 influenced the answers of the majority ,  respondents were shown Figure 3 ( /exchange/ambigfig/etching ) . The majority ( 87% )  responded with answers ranging from a grandfather to William Shakespeare though all indisputably related to a man . When asked what decided their answer , they again replied that it was the white expanse of the forehead and , in some cases , the upper lip . Only two ( seasoned test - takers obviously ! ) said that it  showed a meadow with  grand buildings in the background and a robed woman and the bole of a tree in the foreground .
Though each figure could have elicited more than one equally good spontaneous answer , there was one popular informed guess every time driven by the same reason . The brain evidently pays more attention to comparisons and contrasts than to absolutes . In a world driven by information overload and constant flux , the brain sifts through signals to decide which are worth its while to interpret . It allows large rivers of data to pass through almost entirely unassimilated , peeling off selected data for a close , careful  view ( Jeremy Wolfe , Harvard Medical School ) . Picking the " out of the ordinary " or the different , the high contrast , is perhaps one way in which the brain decides what to focus on .
According to Natalie Angier ( The New York Times , April 2008 ) , the mechanisms that succeed in seizing our attention fall into two basic classes : bottom up and bottom down . Bottom-up attentiveness originates with the stimulus , with something in our sensory field that is the equivalent of a sensory shout - the expanses of white standing out of the dark background in the examples discussed earlier . In comparison , top-down attentiveness is volitional - the decision by the subject that an item , even in the absence of sensory shouts , nonetheless merits attention .
Respondents were shown two photographs of themselves as part of a group , taken in quick succession and with barely perceptible differences . With the photographs removed from view , they were asked if the two photographs were different in any way . Only three ( 20% ) said they were ; interestingly  the only three who had  changed position in some way ( sitting cross-legged / moving hair out of the eyes / smiling in the second photograph ) between the two photographs . The brain concentrates only on what it wants to . Here , one's own image leapt out to the exclusion of all else in the limited time available for viewing the photographs .
Similar behavior was exhibited when participants heard the pun , " the land of the rising sun/son " . Asked what kind of society it might describe , every participant but one came up with " a Japanese society " - a response clearly influenced by geograpy textbooks though the question was a sociological one . The solitary exception ( probably a student of sociology ) averred that it was certainly not a meritocracy . The brain tries to ease its workload by using readily available decoding devices ( in this case knowledge of geography or sociology directing perception ) whenever it can do so .  

Respondents heard the word " teapot " repeatedly and then the word " potty " several times , without any break in the repetition from beginning to end . When asked to identify the word that had just been repeated , more than half answered " teapot " . Only a little over a third caught the switch to a new word .
Respondents were also shown ten cue cards with the phrase , " the bear eats shoots and leaves " on the first nine and " the bear eats , shoots and leaves " on the last card . When asked to explain the sentence , every respondent but one said it described the bear's diet . The sole dissident volunteered that the last card seemed to speak about some kind of a cowboy bear . The change - i.e. the addition of a comma after the word " eats " - registered with just one respondent .
Taking a leaf out of the magician's manual , repetition was used to hide the trick - when observers are faced with repetition , they naturally assume that each repetition is identical . In this , they are encouraged to do so since the brain tends to try and anticipate future perceptions in trying to make sense of ambiguous input in a data-overloaded rapidly changing world .
Covert misdirection ( by a sigh to indicate fatigue with the repetition at the point when the change took place ; not memorable so as not to arouse suspicion ) , was used with half the sample . However , both halves largely overlooked the change in stimuli . People fail to notice that something is different from the way it was before even if it is staring them in the face - the brain , in cutting corners and making do , makes us change blind .
The mind moves in mysterious ways its wonders to perform . The more one studies it , the more one realises how much remains to be understood .
" What is mind ? No matter . What is matter ? Never mind . " ( Ascribed to Thomas H. Key ; 1799-1875 ) .      

SaraO's picture

Optical Illusions

I showed people five optical illusions. Each illusion had a caption, for example, which circle is bigger? I then asked them a few questions. Were they able to answer all of the questions? If so, which ones? If not, why not? Did the illusions evoke any emotional response? Do they hate them? Love them? Did the illusions make them dizzy? Here are the two most telling questions and the graphed results:Question 1Question 1

Question 2Question 2 

For question one I asked if the people were able to answer the questions posed by the optical illusions. 40% said yes to all, another 40% said yes to at least 3, and 20% said no to all. In question two I asked for their responses to the illusions. 80% of people said they were able to figure them out no problem.

My data reports that people claimed to  see through the optical illusions, yet it also reported that about 80% of people got the answers to the yes or no questions in the captions wrong. The lines were parallel, the dots were the same size. 

From this, despite my discomfort with Paul Grobstein's statement, I can conclude that he is probably right. The brain takes what we see and assigns a familiar value to it, when it cannot identify what it is presented with immediately. I thought my results would be skewed because each illusion was labeled illusion, and many people have seen these illusions before. While that was the case, people still relied on what their brain's told them they were seeing, which was wrong. As we continue to simply assign familiar values to the wide world around us, my question is, what are we missing? What do we pass over simply as a result of human error, and our inability to comprehend? We pride ourselves as the species with the ability to think, analyze and create, yet, in that capacity we are still very limited. 

Yellow's picture

And the image

Ambiguous FigureAmbiguous Figure
Yellow's picture

Survey with Optical Illusions

Viewing the imageViewing the image

Results I got. It was interesting that most of the people who took the survey ascribed distinct genders to the two images, and some people described the scene in detail.


Images Simultaneous or Several Seconds Apart?Images Simultaneous or Several Seconds Apart?


Optical Illusions Fun?Optical Illusions Fun? 

akaltwasse's picture

Plato says...

To me, it seems like these illusions are all successfull because of weaknesses in our minds.  Well, maybe not "weaknesses", but visual flaws.  Because I had seen some of the illusions before and learned about color theory in psych, the illusions themselves did not have the best effect on me.  However, I enjoyed our discussion.  But if the mind is so easily tricked, then how can it have the capacity to make sense out of all of these constantly moving particles that make up objects?  That's not necessarily my opinion, but I think the notion that our perception is flawed and that everything just exist because our brains are putting order to chaos was unsettling to the majority of the class.  Much like when you find out how an optical illusion works, some theories can really suck the fun out of things...NOT THAT THE CONVERSATION WASN'T FUN!  In one of Plato's dialogues, Socrates asks Euthyphro, "And if a thing is being led, is it being led because of the leading?  And if being seen, being seen because of the seeing?"  Euthyphro replies with, "Certainly."  The opinion is like what Paul suggested in our discussion: that the table is only in existence, or being seen, because our seeing it and interpreting it exists.

Paul Grobstein's picture

fun and weaknesses? or strengths?

If "the table is only in existence ... because [of] or seeing it and interpreting it," that actually makes us sound not "weak" but rather sort of important, no? And since we can see things in lots of different ways, we can enjoy what discovering/created new things instead of worrying about getting it right? Sounds even more like fun to me ....
mkmerrill's picture

 Just a thought, I could

 Just a thought, I could be totally wrong:

What Paul Grobstein said really made me think about how we perceive the world (or how our brain perceives the world). But I still am confused about the idea that our brain assigns meaning to randomness. If we imagine that our eyes are capable of seeing molecules ( like we did in class), Paul Grobstein says that everything will be one big blu of molecules. I agree with this understanding, but it made me think: aren't molecules held together by attractive forces? (this is why a table is a solid object, right?) If so, even if our eyes were capable of seeing molecules, doesn't it make sense that the bonds or forces between the molecules would still exist? This would mean that even though everything would be a blur of molecules, solid objects would exist (until the bonds were broken). So assuming objects (held together by forces) still exist we (by process of thought) give an object a name, "table". But is the idea that the brain assigns a name (classification) the samee as assigning it a meaning? I think that although the brain interprets things in a way I don't understand, and classifies them, it is people's (physical) interacions with randomness that gives it meaning.


Paul Grobstein's picture

(physical) interactions with randomness

If everybody sees everything (not only poems) a little bit differently, then nobody is "totally wrong" and everybody can get "less wrong" by noticing the differences between how they see things and how other people see them ... and coming up with a new way to see them?

"Bonds or forces" are a useful way to see things in lots of circumstances. But they're not so good in others. The problem in the latter case is that bonds/forces are no less probabilistic than the location or velocity of particles. A "bond" or "force" is a statistical likelihood of an association, not a fixed or invariant relation. So a "bond" or a "force" is a name we give to an observed statistical regularity, and they have "meaning" because of that.

Yes, it is "indeed peoples' (physical) interactions with randomness that gives it meaning." The physical interactor is the brain, and it is organized in such a way that different people will, to one degree or another, have different interactions and create different meanings. Which we can use to have new interactions and create new meanings?

Is that at least a new way of seeing things?

mcchen's picture


I guess if our brains gave meaning to randomness and what we see is what we expect to see, we would never be able to see anything in a different light.  Although in regards to optical illusions, once we look hard enough aren't we able to interpret what seems like a "simple picture" in multiple different ways? I am willing to accept that information can be interpreted in multiple fashions, but that makes me think of an interpretation of a poem or a metaphor in a story; everyone's take on it is supposed to be little different.  In regards to objects we see daily such as a chair or a lightbulb, we all must be interpreting that image in a similar fashion in order to know what it is, but that doesn't mean we all think alike.  Once I think I've sort of understood a part of this topic, another part confuses me, it's a never ending cycle of learning.
Paul Grobstein's picture

"a never ending cycle of learning"

Doesn't sound like you're confused at all. Maybe, learning/life is an "unending" process, and science isn't actually so different from "interpretation of a poem or a metaphor"? (cf Science as Story Telling in Action and Education: Between Two Cultures). Who says what "is supposed to be" about either a chair or a poem? And how much do we actually agree on either?
msmith07's picture

I guess this is a little

I guess this is a little late, but maybe better late than never....


But I was thinking about how, maybe the convention of us all seeing the same object is the same as the convention of naming something? Or perhaps a better analogy, the naming of colors.

I've always thought about people who are colorblind in this way. Say someone sees the color green as blue instead. but if he grow up being told "the grass is green" or "that crayon is green" or "the shirt you are wearing now is green", would he be able to identify them all as green, regardless of whether or not the signal is being interpreted by his brain as my version of green? How do we know that my version of purple and your version of purple are the same thing? We've both been told that the same crayon goes by the name of "purple" all our lives, but maybe your brain interprets your version of purple to be something much closer to my version of orange?


Am I making sense? Or perhaps just rambling. It's just a thought I've thought on occasion..

Serendip Visitor's picture

com[lex issue

I had this very problem as a child. Later I learned that there are visual pigmenst that absorb different ranges of light wavelenghts, so I figured that green is green and red is red. Then I learned more about the brain and how it interprets information. There is no law saying that electromagnetic inputs HAVE to be interpreted visually, and actually, the infra-red is interpreted as heat. It has been speculated that dogs, for instance, might (and perhaps do) interpret smells as colours. Who knows? I am just an evolutionary biologist, but I am sure some cognitive neuroscientists has devoted his/her intire life to that problem.

swhitt's picture


I'm still trying to wrap my head around our discussion yesterday. Someone in class referred to our shared perception as a collective construct and it started me on the following train of thought:

Even as we are composed of clustered molecules, our joining together each week for class creates another cluster (that disperses in a relatively short period of time compared to the molecules of a table).  What are the defining characteristics of this cluster? What traits could we ascribe to our group (if our eyes were too big to see people as individuals) and how could our cluster be manipulated (as we can manipulate the molecules of a tree by cutting it down to make a table). I also wonder how the molecules that create the tree choose to group/adhere? Do they self select intuitively (like moths to light), intentionally (like us?), or through external design? Are the ties that bind molecules together, which gradually weaken over time, like the ties that bind people to each other?

I noticed that there's a string on Paul's serendip blog re: the benefits of dialogue/collaberation between scientists and humanists - I was struck by the same thing in class. The way our conversation grew by flowing from literary ideas to scientific explanations and back again was illuminating.

I'm more in the humanist camp myself and I'm interested in getting together with some scientists to further explore the ways we interpret our world. If anyone else feels the same way, let me know!

Paul Grobstein's picture

from literary ... to scientific ... and back again

Glad to provide something to think about. And glad to have something to think about in return. Very interesting extension and questions about what causes entities of different sorts to group/cohere. Betcha the answer is that there are some significant similarities between what binds molecules together and what binds people together but also some significant differences (molecules don't construct stories). For more along these lines, see /complexity/course/emergence07/ (offered again this spring).

Happy to get together "to further explore the ways we interpret our world," as per /sci_cult/TwoCultures.html

stephkim's picture

proof from today

Found this on the internet:


hope it helps haha

Paul Grobstein's picture


Bemused that you trust something on the internet more than you trust .... me? Will get over it though, and like the thing you found. Send me or post the URL so I can add it to the links at the end of /bb/neuro/neuro04/checkercomp.html ?
swhitt's picture

It does help - very cool;

It does help - very cool; thanks!