Author Archives: Ka Ki Kwok

Are roller-coasters risky?

Whenever I go to a amusement park, I always go rIde the most thrilling roller-coaster. However, I am always the only one among my friends who is not afraid of riding roller-coasters. My friend always ask me: don’t you feel like you are risking your life by riding roller-coasters? I really want to prove them wrong but I feel like I do not have enough evidence. Since our class has been discussing the risk of vaccines, I think I can write a post about the risk of riding roller-coaster.

A lot of anecdotes

Andrew emphasized that anecdotes are very powerful. My friend’s story serves as a great example. My friend used to play those most terrifying roller-coasters, until she heard that a friend of hers got stuck on a roller coaster upside down for around 40 minutes. She was frightened after her friend told her the story and said she will not ride roller coasters anymore. 8sgyJbmThis reminds the cheerleader’s story we watched in class which is a very powerful anecdote at that time that causes many people to believe in the danger of vaccines, although it turned out to be a lie.

Similarly, a lot of roller coaster accident happened in the past years. When I searched for “the worst roller coaster accident” the result came out are just painful to see. According to usatoday, a women was thrown out of a roller coaster and died in Six Flag in Texas. Accidents must have affected so many people, especially those who are eye witnesses. A witness of the six flag accident Ashley Steffen tweeted, “The fact that woman fell from the six flags roller coaster & died makes me never want to ride one again.”

How likely is death and injuries caused by roller coaster?

What is the chance of a person being killed or injured on a roller coaster?  When I searched online for statistic, I cannot find any specific report on the statistic of death and injuries on roller coasters. According to, “there are over 297 million people in the United States alone that have had the opportunity to ride 1.7 billion different amusement park rides, most of which being roller coasters.” The Association of Amusement Parks and Attractions concluded that there is only 1 over 24 million chance of being killed on roller coasters and 8 can be injured in every million days. According to the guardian, going fishing is even more risky, with 88 hqdefaultinjuries every million days, than riding roller coasters. I can say the relative risk is that injury when fishing happen 11 time more likely than injuries on roller coasters. However, I think bias can exist because the data is from the Association of Amusement Parks and Attractions so the number of death might have been underestimated.

There are some extremely contradicting datas such as this, which said that there are 20 injuries in amusements park everyday. Research collected data from emergency rooms across America during the time period of 1990-2010 and found that around 93,000 children are injured on rides in amusement park. However, people are actually more likely to be killed on the car ride to amusement parks than on the rides in amusement parks. As we talked about in class, car crashes kill 40,000 each year, which means around 100 everyday.

In conclusion… 

I found that it is very hard to gather exact data of deaths and injuries on rides as the Association of Amusement Parks and Attractions can be a huge bias. Also, it is hard to determine what exactly mean by roller coaster accident death because many people were killed by roller coasters when they are not the rider. Researchers or reports always analyze by “rides”, which include many rides other than roller coasters in amusement park. I cannot even find consistent datas online. More reports are definitely needed. However, I cannot say roller coasters are safe but I can say you are more likely to die in a car crash than on a roller coaster.

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Does natural delivery make babies smarter?

Women who are about to have a baby always try to give birth naturally because they believe that natural delivery benefits the babies and also the moms in various ways. Since I was young, I heard many people saying that babies who are delivered naturally will be more intelligent than those who are delivered via c-section. Because I was born through c-section, I wondered if I am really less intelligent than those who are born naturally. I am going to focus my post on the relationship between c-section, natural birth, and intelligence.ebce67f04dc849c489ef71affd9cb4dd

“Ucp2” that “boost” your brain. 

There is a research by Yale School of Medicine which shows that a protein called “Ucp2” in our hippocampus can be triggered during natural birth. The expression of Ucp2 can benefit brain development. According to the study, it “regulates neuronal differentiation of the hippocampus”. Researchers conducted studies measuring the Ucp2 expression on mice that are born through c-section and naturally. The result was consistent to the hypothesis that mice born naturally has more Ucp2 than mice born via c-section.

When I searched “c-section and intelligence” on google, every articles that come up are about babies delivered naturally have higher IQ. Also, every articles, such as this and this, are based on the research I mentioned above. However, although the research did prove that naturally born babies have more Ucp2 that can boost the development of babies brain, there is no exact link between high Ucp2 and high IQ.

Other research says NO

Question the link between Ucp2 and IQ, I found another study which failed to reject the null hypothesis: deliver method has nothing to do with intelligence.

First stage of the experiment: researchers used a sample size of 5000 children from age 6-7 randomly selected from a examination for entering primary school in Iran. Researchers collected data from their mother to see whether they are delivered via c-section or naturally. Second stage:  two matched groups consisting of 189 children were selected. The children all have similar conditions such as “maternal age, parity, paternal education, birth ranbaby-braink, and use of kindergarten and child’s rank”. This ruled out some of the potential confounding variables.

To my surprise, the result from the first stage shows that children delivered via c-section have significantly higher IQ score than children delivered naturally. This is under the condition that mother and father’s education are not controlled. In the second stage, when they put potential confounding variables, such as parents’ education, in control, there are no significant difference in IQ score between children delivered naturally or via c-section. Researchers therefore concluded that IQ score may not be linked to deliver method. Instead, it is more likely to be linked to parents’ education level.

So… What’s the answer?

After looking at both studies, I should say that there is yet no sufficient evidence that can reject the null hypothesis (deliver method has nothing to do with intelligence). The first study can only show the relationship between Ucp2 and deliver method, but not Ucp2 and intelligence. The second study shows how children’s IQ are affected by parents’ education rather than delivery method. However more studies have to be done in order to reduce the chance of it being a fluke. I think it may be that Ucp2 can be a “booster” for babies brain, but how the brain develop still depends on factors like parents’ education level, environment, and so on. Therefore, we probably cannot say that natural delivery makes babies smarter.

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Cats and their magic power?


I am a animal lover. This friday, I passed by a pet store and their was a cat waiting for adoption. I went in front of its cage and it reached out its paw from the cage. I petted it through the cage and I just feel very happy and relaxed. After I go home, I kept wondering if pets, or cats, really have a calming effect. I searched online and found out that cat owners have lower heart attack risk.  

Cat helps with heart diseases.

Having a cat as a pet can actually lower your risk of having heart attack or other cardiovascular diseases by nearly 30 percent. There was a research that studied 4435 participants and 2435 (55%) of them are cat owners.  I think this is a relatively big sample size. Participants who are healthy and without cardiovascular diseases, entered the study in 1970s and were followed up for 10 years. The null hypothesis would be owning a cat has no effect on lower risk of heart diseases and the study result has rejected the null hypothesis, showing evidence that owning a cat is related to lower heart diseases risk. The study adjusted some potential confounding variables such as “age, cholesterol, race/ethnicity and cigarette smoking”. The result shows that past cat owners have significantly lower risk of death due to heart diseases. It also shows a trend of increasing risk of death due to heart diseases for those who do not own a cat. On the other hand, surprisingly, owning a dog does not have any association with reducing heart diseases.

However, correlation does not equal to causation. The research result does not mean having a cat cause you to have lower heart diseases rate. As the research has also mention, the reason of this result may be that those people who own a cat has different lifestyles than those who do not own a cat or own a dog. Maybe for a cat owner, they spend more time just sitting there and petting their cats. Unlike those who own dogs, who have to walk their dogs everyday. Having a cat may also have relationship to having a more harmonious lifestyle. Therefore, although some of the confounding variables are in control, there can still be other variables that may affect the result.

”Put a cat in a room with a bunch of broken bones – the bones will heal.”

Other than the fact that owning a cat can help enhance your heart health, cats’ purr is believed to have healing power. The above saying is from old veterinarians and it is still known nowadays. Cats’ purr can not only heal bones and soft tissues, but can also decrease the symptoms of dyspnea. Dr. Clinton Rubin’s research has proved that bones can heal when exposed to sound frequencies between 20-50 Hz. A cat’s purr is exact 25 Hz and 50 Hz.

Elizabeth von Muggenthaler, a research scientist and bio-acoustic specialist, did research that downloadshows that cats’ purr heals by recording the frequency of members in the cat family. An interview with Elizabeth online tells us about Elizabeth’s research. She claimed that all kinds of cats have a purring frequency at 50 Hz and it can help with “muscle, tendon, ligament injuries, joint injury, wound healing, reduction of infection and swelling, pain relief, and relief of chronic pulmonary disease.” Cats can purr when they are in pain and the purring is believed to be self-healing. The article mentioned that researches and statistics have shown that cats have much lower tendencies than dogs to have bones or muscle injuries. However, I think this may not be directly related to the healing power of cats’ purr. It may because of life dogs include much more running around and jumping; or it may because of the difference between cats and dogs’ bone structures.

Although many people do believe that cat purring heals, there is yet no scientific evidence for us to reject the null hypothesis (cats’ purring has nothing to do with healing) and more statistics and researches should be needed.

In conclusion, owning cats are proved to be correlated to lower risk of having heart diseases but whether cats’ purring has healing effect still need more scientific studies. However, those of you who own a cat can try to put them by your side while sleeping to try if you really have a different feeling.

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Go to sleep after studying!

Many of you may be struggling on when is the best time to study. Although you may think going to sleep immediately after studying may cause you forgetting all the things you have studied, study has shown that our brain memorize the best when we go sleep immediately after studying.

Sleep is important for memory!

There has been previous research saying that sleep enhances our memories using a untraditional memsleep
ory system. The research is from Michigan State University and the lead researcher Kimberly Fenn stated, “there is substantial evidence that during sleep, your brain is processing information without your awareness and this ability may contribute to memory in a waking state.” This ability, however, varies in the 250 participants of the study as most people showed huge improvement in memories but some showed no enhancement. From this study, we know that sleep is an essential element for improving study efficiency.

Let your brain rehearse the information! 

Have you ever experienced studying overnight for a exam but forgetting everything during the exam? Have you experience the helpless feeling when you know you have studied this but it is just not coming up? This happens because your brain need time to ‘rehearse’ the information processed. There is a study a year later that shows that going to sleep after studying can make our memories fade much slower. The study was carried out among 207 Harvard student who were required to remember a set of related and unrelated word pairs. Participants were randomly assigned to do a retest after 30 minutes (morning memoryand evening), 12 hours (with sleep and without sleep), and 24 hours (with sleep). The result supported the hypothesis. For the 30 minutes retest, the result did not show a difference between the morning and evening period, meaning studying during daytime or nighttime does not influence short term memories, For the 12 hours retest, those who slept overnight has a significantly better result in remembering unrelated word pair comparing to those who stayed awake all the time. Similarly, in the 24 hours retest, those who started studying at 9 p.m. and went to sleep immediately after studying has a better result than those who started studying at 9 a.m., stayed awake for 12 hours first, and then went to sleep. The difference between 12 hours and 24 hours retest is that the 12 hours group shows difference in result in the two types of word pairs but the 24 hours group has similar results in both word pair types. The conclusion is that going to sleep after studying results in better memorization of information. (Of course there is still chance that it is a false positive.)

It made me think of my experience of my first psychology exam. I started study at night and went to sleep thinking I still have a lot of things that I can’t remember. However, during the test next morning, I suddenly feel like I can remember everything that I read the night before, including those I thought I would have forgotten. This may because I went to sleep immediately after study and it tells my brain to memorize the information.


The mechanism is still unclear because it is hard to conclude whether sleep enhances memory or being awake lead to memory lost, as the research has also mentioned. Maybe the mechanism is related to Kimberly Fenn’s research that we are not using the traditional system to process informations during asleep and this helps with memorizing the information given to the brain just before sleep. Even though we do not know the exact mechanism yet, the study can still be correct. However, more studies should definitely be done. The one question I thought of after looking at this study is that, does the time of sleeping matters in this condition? Will sleeping for 3 hours or 8 hours make a difference in memory retention? Also, will sleeping during daytime or nighttime affect the result too? Leave your comments below if you have any thoughts!

Final word and you may have heard of it thousand times already: Never ever study overnight.

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Improve your health by sleeping right!


Do you know which position do you sleep in? We spend one third of our day sleeping in bed. I tend to sleep on my back (Starfish!) more than on my side or stomach. There is a recent research which shows that a right sleeping position can help us avoid neurological decline. Research was conducted by researchers at Stony brook University and they found that sleeping in lateral position help to remove brain wastes faster than sleeping in other positions does.

What do our brain do when we are sleeping?

Sleeping position can help removing wastes that can ‘clog’ our brain. The removal of brain waste depends on our glymphatic system. According to previous researches, just like our lymphatic system which transport wastes out of our organs, our glymphatic system is the disposal system for our brain. It works most effectively when we are sleeping. The build up of brain waste can affect our neurologic system negatively increasing the possibility of getting neurological diseases like Alzheimer’s. According to theguardian, blood vessels carrying cerebrospinal fluid pick up wastes by exchanging with the interstitial fluid in our brain in the process of entering the intercellular space in our brain tissue.

Research on mice 

The researchers conducted an observational study by measuring the exchange rate of cerebrospinal fluid and interstitial fluid in mice’s brain when they are put to sleep on their side (lateral), back (supine), and stomach (prone). The figure below is from the research paper which shows the “retention” and “loss” of a chemical (Gd-DTPA) injected to the mice’s brain. The higher the rate of retention, the slower the exchange rate cerebrospinal fluid and interstitial fluid, meaning slower the waste cleaning process. It shows a difference in the brain’s efficiency of clearing waste in different sleeping position.


This study has rejected the null hypothesis and therefore it is either correct or a false positive. When I searched about this topic online, I only found this research paper which means that more researches should definitely be done. A meta-analysis should be used to minimize the chance of the result being a fluke. Although the mechanism seems to be clear in this research, we still cannot eliminate chance. Also, since this is not a controlled trial, we can never fully eliminate the presence of confounding variables and reverse causation. A confounding variable can be the use of a anesthetic. It can influence the sleeping pattern of the mice and lead to different result from normal sleeping, as the study mentioned.

Since this study is only conducted on rodents, there are a lot more possibility and difference in human. The study also mentioned that researchers can not yet measure the effect of change in sleeping positions on the brain. This study reminds me of Dr. Spock’s study of babies’ sleeping position which killed thousands of babies. This also tells us our sleeping position can have a huge impact on our body. I am wondering what would be the difference if our body is in supine position but head is turned to the side because this is the position I am always in. However, I believe after looking at the study, we should all try to sleep on our side.


Work Cited:

Lee, H., L. Xie, M. Yu, H. Kang, T. Feng, R. Deane, J. Logan, M. Nedergaard, and H. Benveniste. “The Effect of Body Posture on Brain Glymphatic Transport.” Journal of Neuroscience 35.31 (2015): 11034-1044. Web.

Costandi, Mo. “How to Optimise Your Brain’s Waste Disposal System.” The Guardian, 22 Aug. 2015. Web. 15 Oct. 2015.

“Could Body Posture During Sleep Affect How Your Brain Clears Waste?”Could Body Posture During Sleep Affect How Your Brain Clears Waste?Stony Brook University, 4 Aug. 2015. Web. 15 Oct. 2015.



What do you believe?

Are you one of those that would look at daily horoscope and believes that today is your lucky day? Do you believe in fortune-telling? Or are particularly superstitious about something? I am absolutely not a superstitious person nor someone that would belief in paranormal stuff. However, I am always curious about what kind of people would believe in it and how does these belief affect certain people. A research showed that people who believe in paranormal phenomenons tend to have a higher external locus of control.


As a Chinese, there are many superstitious people around me and I always wondered what made them believe in Fengshui or other things. Few years ago, a good friend of mine was diagnosed a tumor on her spinal cord and she will loose her life if the condition is worsened. Got the shocking news, my friend’s mom and dad went to a fortune-teller and they were told that it was my friend’s first name which caused her bad luck. The fortune-teller gave them a new name for their two daughters and they went through legal procedure to change the name for my friend and her sister. After a surgery and a long period of recovery time, my friend finally got better. Her parents believe that it was her new name which saved her.

I came across an interesting research paper titled “Personality correlates of paranormal belief: Locus control and Sensation seeking”. The hypothesis of the research suggests that the more people believes in paranormal phenomenon (x-variables), the more they are likely to have a higher external locus control and more sensation seeking behaviors (y-variables). Participants of the research were 81 women students and 9 male students with the age range from 17 to 47. Questionnaires were given to the participants and Tobacyk and Milford used their own “Paranormal Belief Scale”, which provides measures of “belief in traditional religion, belief in phi phenomenon, witchcraft, superstitious, spiritualism, extraordinary lifeforms, and precognition”.


The research result proved the hypothesis that the more a person believes in paranormal phenomenon (especially spiritualism and precognition with correlation coefficients of -0.36 and -0.44), the greater is their external locus control, which I am not surprised. However, not every form of paranormal belief is negatively correlated with locus control. Out of my expectation, the result shows that the more a person believes in superstition, the greater is their internal locus control. The definition according to Tobacyk and Milford is that “individuals can engage in superstitious behavior and thereby exert control by avoiding back luck.” This make me think of my friend’s parents changing their daughter’s name. What I also found surprising is that the research did not show a significant relationship between belief in paranormal phenomenon and sensation seeking. As I always see videos of people shooting paranormal activities they experienced on YouTube, it definitely a result I did not expect.

However, because the putative causal variable is not manipulated, this study cannot avoid reverse causality and confounding variables. There may be reverse causality because it is possible that when a person has a more external locus control, he/she will be more easily influenced by other factors such as friends’ persuasion and online source, which cause him/her to believe in those paranormal phenomenons, or when a person firmly believes in paranormal phenomenon, he/she believes that he/she does not have the control of their own life. There are also some confounding variables in the experiment such as the gender of the participants, and participants’ self-cognition. The participants are mostly female and they might tend to be more easily influenced by others or more likely to be superstitious. I believe there might be a difference in the result when the questionnaire was carried out to all male participants. Also, the participants’ self-cognition can influence the study result as everyone has different self-perception and they may think of themselves differently. Moreover, the way the questionnaire is constructed can also influence the result. When I did my further research on the topic, I came across a revised “Paranormal Belief Scale” by Tobacyk, which I think is a better way of measuring people’s belief of paranormal phenomenon because it used more subjective questions. Lastly, of course, we can never eliminate chance.

I believe that I am in control of my life and I do not believe in paranormal phenomenons, but as we have discuss in class, science can easily prove something to be wrong but can hardly prove something to be right. This research showed that there is correlation between belief in paranormal phenomenon and personality but there is no certainty. I cannot say that my friend’s parents have more external locus control because of that one incident. Belief in paranormal phenomenon must be related to many other factor and I am really interested in knowing more.


Work Cited:

Tobacyk, Jerome J. “A Revised Paranormal Belief Scale.” PsycTESTS Dataset(2011): n. pag. Web.

Marnat, Gary Groth, and Julie Ann Pegden. “Personality Correlates of Paranormal Belief: Locus of Control and Sensation Seeking.” Social Behavior & Personality: An International Journal (1998): 291-96. Web

Finger length tells you everything?

Look at your index and ring finger. Then think about what did you got for your SAT. Do you believe that these two totally unrelated things: finger length and SAT scores actually has correlation? Do you know that only by looking at one’s finger length you can tell many things about that person.


A new research claimed that kids with longer ring fingers compared to index fingers are likely to have higher math scores than literacy or verbal scores on the SAT, while children with the reverse finger-length ratio are likely to have higher reading and writing, or verbal, scores versus math scores. As what we talked about in class, there is ‘z’ factors affecting the correlation between finger length and SAT scores. That factors are hormones called Testosterone and estrogen. The exposure of these hormones in wombs can affect children’s certain areas of brain. The research claimed that exposure to testosterone in the womb promotes developments of area of brain that is associated with spatial and mathematical skills, while exposure to estrogen promotes development of areas of the brain that is associated with verbal ability. Testosterone makes the ring finger longer, while estrogen makes index finger longer.

Mark Brosnan of the University of Bath, who lead the study and his colleagues made photocopies of palms of children who took the exam and measured the length of their index and ring fingers extremely accurately (0.01 millimeters). They used the finger-length ratios as a substitute of the levels of testosterone and estrogen exposure. They compared the finger length and the children’s test performance (boys and girls separately) and the result shows that there is a strong correlation between the high exposure of testosterone, indicated by longer ring finger than index finger, and higher scores in math. On the other hand, they looked at those girls who has lower testosterone exposure, indicated by longer index finger than ring finger, has higher literacy scores (reading and writing). Moreover, when they compare all children’s test performance and finger length ratio, they found that those with relatively long ring finger (higher exposure to testosterone) tend to have a wider gap between performance on math and literacy.

In fact, finger length ratio can not only predict children’s SAT scores, but also many other stuff you wouldn’t think of. There are studies about using finger length to predict one’s sexuality, personality. and even career path. It seems like finger length has correlation to many things, but actually it is the testosterone and estrogen causing the correlations.



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Initial blog post

Hi, I’m Tracy Kwok from Hong Kong and I studied in a high school in Long Island for my junior and senior year. This is my freshman year and I am planning on double majoring hospitality management and psychology.

At first, the reason why I chose this course is that I need it for my general education requirement and there is no other courses that I wanted to take. However, when I received the syllabus during the first class, I found this class really interesting. I am really interested in those topic we are going to talk about and I am actually really curious about the questions we are going to discuss. The reason why I am not planning on having a science major is that I am never really a science person. I liked biology in high school but I was not good at chemistry and physics. I also would not pursue career in science field. However, I would like to know some interesting scientific facts through this course.

Here is a video we watched in our psychology class about Capuchin monkeys reject unequal pay which I found really funny.