Daily Archives: October 29, 2016

Post Traumatic Stress Disorder has plagued human beings since the beginning of time. Whether it being referred to as shell shock, combat exhaustion, battle fatigue, or PTSD it has been a problem that effects the lives of combat veterans, first responders, and anyone else involved in a traumatic experience.  Although physicians and the rest of society are more informed of the problems PTSD causes for those suffering from it, there are still many questions on how to best treat it.

People suffering from PTSD show a variety of signs and symptoms. These include but are not limited to trouble sleeping, nightmares, depression, feeling isolated from the rest of society, among other things. There is no long term cure  for PTSD that is fully accepted by Doctors around the country. Doctors have been experimenting with the use of Eye Movement Desensitization and Reprocessing (EMDR) treatment in hopes of relieving stress in their patients. EMDR’s workImage result for edmr treatment by patients and therapists discussing negative memories and linking them to specific eye movements, usually by moving a finger or small object back and forth in front of the patients face. Afterwards these eye movements are linked to positive thoughts in hopes that the same eye movements made when thinking of a traumatic event will translate into something positive.

EMDR was first discovered in 1980 by Dr. Francine Shapiro. One day Dr. Shapiro took a hike through the woods and noticed her stress had nearly disappeared as she moved her eyes back and forth to observe her surroundings. After realizing the relief she felt from this, she asked her patients to try, and it was met with great success. There are two explanations as to why patients feel relief after EDMR treatment. The first, is the belief that EDMR effects the patients Rapid Eye Movement (REM) sleep. REM sleep is the stage of the sleep cycle closely associated with dreams. During the REM cycle a persons eyes are still active, often moving back in forth. When patients feel relief during EDMR therapy it is believed that this relief translates into a more relaxed REM cycle, therefore the patient receives a more restful sleep. The second, is the belief that the patient uses both the left and right side of the brain in order to follow the object being waved in front of their face. The benefits of synchronizing both sides of the brain are having a better perception  of reality, self awareness, and feelings of optimism.

EDMR’s growing popularity has sparked debate within the science community. The first controlled study was conducted in 1989, by Dr. Shapario. In this study of twenty- two people one group underwent EDMR treatment, while the other under went group therapy sessions, another common treatment from those suffering from PTSD. Her studies concluded that the first group who went through EDMR felt relief after the first session, while those in group therapy felt little to no relief at all. Scientists within the community challenged Shapario saying that she was biased to the group who underwent EDMR, because she had developed the therapy. Other arguments were that the trial was too small, and that there was no way of measuring who suffered from worse cases of PTSD. A number of both controlled and uncontrolled studies have taken place since Shapario’s study. The general consensus is that EDMR often does offer relief to patients, but there’s no way to measure the results or tell if this is due to other variables. Scientists opposing the effectiveness of EDMR make the argument that it could be due to the placebo effect, third variables, and negative results not being published (file drawer effect).

Debates over EDMR’s effectiveness are still going on today. There are no solid explanations or results linking EDMR to relief but many organizations around the country have adopted the practice, based off the fact that many patients feel better after receiving the treatment.  Since its formal introduction in 1989, more than 20,000 psychologists have studied EDMR. As the practice continues to grow it looks like EDMR will be a preferred treatment method for patients who suffer from PTSD.

First picture

Second picture






Do predators eat each other?

Do predators eat each other? Do they only eat herbivores? These questions have been in my mind for a while. Whenever we hear or read the word “lions” we immediately connect it to savagery toward people or fierceness and sometimes to Penn State which is, of course, because of Penn State Logo. However, writing about Penn State’s connection with Lions is not what made me write this post. What brought lions, predators in general, to my attention is that we often hear stories or watch videos that are only about predators attacking or predating on humans or herbivores. So I asked myself if predators do really eat other predators and if yes, why is it not common and what are the reasons we do not hear about cases where predators eat each other, and finally whether there are any correlations or causation relationships. So I decided to write about this topic and do some research on the internet.

The null hypothesis being tested: Predators do not predate on other predators.

The Alternative hypothesis being tested: Predators do predate on other predators.


Image Found Here

According to a post written by Darren Naish, cases where predators predate upon other have been noticed by biologists and ecologists many times. This phenomenon was called intraguild predation by Polis et al (1989). An observational study on intraguild predation was conducted by Palomares & Caro (1999). They recorded 27 cases that were reported as intraguild predation cases and studied them. They noticed that the most common case among the other cases was the one in which adults predated on babies of the same species. However, that the study did not include an analysis of why predators would do that nor did it mention any information about the animals themselves, the atmosphere (i.e. if they are in a typical condition), or whether or notthey are starving at that time and had no other option but to predate on the younger one, as it known and natural for a starving animal to eat another animal from the same species in order to survive. In addition, I think that the number of cases recorded was very small. Furthermore, because the study did not say a lot about the what was measured, I cannot say if it suffers from the Texas Shooter Problem, however, the study got published, therefore the results do not suffer from the File Drawer Problem. In my opinion, I think that the findings of the study did not help me make a decision on whether or not I should reject the null hypothesis. So I decided to do more research about this matter.


Image Found Here

I found another article in an academic website called Wiley Online Library written by FABRIZIO SERGIO and FERNANDO HIRALDO, two scientists who decided to do a meta- analysis study on previous studies that focused on intraguild predation. The data they found was “for 39 experimental studies on 63 populations belonging to 11 killer species and 15 victim species.” After analyzing these studies, they found out that the results were almost consistent with the results of the study done by Palomares & Caro even.

The study results suggested that intraguild predation is very common in their natural habitants whenever external factors that might make predators predate on other predators are present, such as predation pressure which includes the habitant size in the experiment, the risk of predating the prey, and the number of predators and non-predators’ species in the experiment. Individuals of the prey species responded to predation pressure through direct spatial avoidance, risk-sensitive habitat. The study also suggests that there is a correlation between the number of killer (predators) and victim (herbivores) species in the provided space or habitant in an experiment. They noticed that the higher the number of herbivories in the experiment, the lower the number of intraguild predation cases recorded and vice versa.

While the study results can be due to chance, I think that the study was well- conducted and that it is highly unlikely that these study results are false negative, in other words, were due to chance or due to another confounding variable such as an odd biological variable in the animals being tested in the study that made them eat each other and that predators do not in fact predate on other predators, as the study is a controlled trial experiment, which is, as we learned in class, more reliable than an observational study. Also, not only did the researchers study use a big number of animals in the experiments, but they also done the experiments in different locations, which, as Andrew mentioned in class can eliminate any third variables that could appear in small or observational studies. And of course the study does not suffer the File Drawer Problem because it got published nor the Texas Shooter Problem, because the study is experimental and not observational.

I also think that the study should have focused on only one species so that they can more accurate and precise results, as it is known that an animal behavior significantly differs from one to another. In addition, studying one species can help them examine the effects that could results from the intraguild predation phenomenon among animals in that species. Other than this change in the study, I think that everything else was well-done.

Finally, the meta-analysis study results are consistent with the alternative hypothesis and show that predators do hunt each other; however, this phenomenon often happens because of predation pressure such as lack of food or the population size in their habitat and seldom happens in identical conditions, where the number of herbivories is significantly higher than the number of predators in a certain habitant. Furthermore, many well conducted meta-analysis studies were done by researchers that also showed consistency with the alternative hypothesis such as in an article named as the biological control: theory and practice, which supported the hypothesis and even provided evidence of why it happens and how it is actually a good thing!!



Intraguild Predation



SERGIO, F. and HIRALDO, F. (2008), Intraguild predation in raptor assemblages: a review. Ibis, 150: 132–145. doi:10.1111/j.1474-919X.2008.00786.x

URL:  http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919X.2008.00786.x/abstract

Pictures Sources

Lion vs Cheetahs


Lion vs Lion


biological control: theory and practice

Kindlmann, P. & Houdková, K. Popul Ecol (2006) 48: 317. doi:10.1007/s10144-006-0006-4