How Does Your Facebook News Feed Affect You?

Researchers at Facebook, Inc., the University of California, San Francisco (UCSF) and Cornell University teamed up to study whether manipulating the News Feeds of Facebook users would affect the emotional content of the users’ status updates or postings. They recently published their findings in the PNAS paper “Experimental evidence of massive-scale emotional contagion through social networks”  and suggest that they have found evidence of an “emotional contagion”, i.e. the idea that emotions can spread via Facebook.


The size of the study is quite impressive: The researchers analyzed the postings of 689,003 Facebook users (randomly selected based on their user ID) during the week of January 11-18, 2012! This probably makes it the largest study of its kind in which social media feeds of individual users were manipulated. Other large-scale social media research studies have relied on observing correlations but have not used actual interventions on such a massive scale. The users’ postings (over three million of them) were directly analyzed by a software which evaluated the emotional content of each posting. The researchers did not see the actual postings of the Facebook users, which is why they felt that their research was covered by Facebook’s Data Use Policy and did not require individual informed consent. This means that the individual Facebook users were probably unaware of the fact that their News Feeds were manipulated and that their postings were being analyzed for emotional content.


The researchers selectively removed items with either “positive” or “negative” emotional content from the News Feeds of individual users. The emotional content of News Feed items was categorized using the LIWC software, which defines words such as “ugly” or “hurt” as negative and “nice” or “”sweet” as positive. Each emotional post had a 10%-90% chance (assigned based on their User ID) of being removed from the News Feed. Since removal of News Feed items could have a non-specific, general effect on users being exposed to lesser updates, the researchers also ensured that they studied control groups in whom the same number of News Feed items were randomly removed, independent of their emotional content.


Importantly, 22.4% of posts contained “negative” words, whereas 46.8% of posts contained “positive” words, suggesting that there is roughly a 2:1 ratio of “positive” to “negative” posts on Facebook. This bias towards positivity is compatible with prior research which has shown that sharing of “negative” emotions via Facebook is not always welcome. The difference in total number of “positive” and “negative” posts forced the researchers to use two distinct control groups. For example, users for whom 20% of News Feed posts containing “positive” content were removed required a control group in which 20% of 46.8% (i.e., 9.36%) of News Feed items were randomly removed (regardless of the emotional content). On the other hand, users for whom 20% of News Feed items containing “negative” content were removed had to be matched with control groups in which 20% of 22.4% (i.e., 4.48%) of posts were randomly removed. The researchers only manipulated the News Feeds but did not remove any posts from the timeline or “wall” of any Facebook user.


The tweaking of the users’ News Feeds had a statistically significant impact on what the users posted. Removing “positive” items from the News Feed decreased the “positive” word usage in the users’ own postings from roughly 5.25% to 5.1%. Similarly, removal of “negative” News Feed items resulted in a reduction of “negative” word usage in the posts of the negativity-deprived users.The overall effects were statistically significant but still minuscule (changes of merely 0.05% to 0.15% in the various groups). However, one has to bear in mind that the interventions were also rather subtle: Some of the positivity- or negativity-deprived subjects only had 10% of their positive News Feed items removed. Perhaps the results would have been more impressive if the researchers had focused on severe deprivation of “positivity” or “negativity” (i.e. 90% or even 100% removal of “negative”/”positive” items).


The study shows that emotions expressed by others on Facebook can indeed influence our own emotions. However, in light of the small effect size, it is probably premature to call the observed effect a “massive-scale emotional contagion”, as the title of the PNAS paper claims. The study also raises important questions about the ethics of conducting such large-scale analysis of postings without informing individual users and obtaining their individual consent. The fact that the researchers relied on the general Facebook Data Use Policy as sufficient permission to conduct this research (manipulating News Feeds and analyzing emotional content) should serve as a reminder that when we sign up for “free” accounts with Facebook or other social media platforms, we give corporate social media providers access to highly personal data.
Kramer, A., Guillory, J., & Hancock, J. (2014). Experimental evidence of massive-scale emotional contagion through social networks Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1320040111


Lab Grown Organs and Artistic Computers in Fifty Years?

The Pew Research Center released the 2014 survey of U.S. adults (1,001 participants, surveyed by land-line or cell phone interviews) regarding their views on technological advancements in the next 50 years.

Robot – via Shutterstock

Over eighty percent of the participants said that “People in need of an organ transplant will have new organs custom made for them in a lab” and roughly half of the participants felt that “Computers will be as effective as people at creating important works of art such as music, novels, movies, or paintings” within the next 50 years. The vast majority did not think that humans will be able to control the weather during the next few decades.

As someone working in the field of vascular and tissue engineering, I think that the perception of scientists being able to engineer transplantable organs within 50 years is realistic. We have made quite a bit of progress in the past decade when it comes to deriving functional tissues from stem cells, but we still need more research before we will be able to build functional organs. It may take a decade or two before we can reliably generate these organs, and even longer to teat and optimize them for therapeutic purposes, and to ensure their long-term survival in transplant recipients.

50 year predictions

The reason to be optimistic about engineering organs is that we have already seen examples of engineered tissues and small organoids being implanted into animal models. There are also ongoing early clinical trials with patches of engineered tissues and engineered blood vessels. Scaling up these successes to whole organ engineering in humans will be challenging but sounds feasible.

I am surprised by the fact that half of the U.S. adults believe computers will be “effective” at creating works of art within the next 50 years. Do we have preliminary evidence – even at a small scale – that computers can currently “create” art? Perhaps this comes down to our definitions of what constitutes “creativity”. One could envision computers generating paintings, music and novels based on existing art created by humans. But is that true creativity? Then again, when humans “create” art, they also base their new product on their experiences and prior art created by other humans. Maybe computer-created art in fifty years isn’t  far-fetched after all.


Attitudes towards changes

Not everyone is enthusiastic about new technologies.


When asked whether it would be a change for the better or a change for the worse……


1) “If most people wear implants or other devices that constantly show them information about the world around them”

2) “If lifelike robots become the primary caregivers for the elderly and people in poor health”

3) “If personal and commercial drones are given permission to fly through most U.S. airspace”

4) “If prospective parents can alter the DNA of their children to produce smarter, healthier, or more athletic offspring”


…the majority of participants felt they would be worse off with these changes.

The way the questions were phrased did not leave room for a more nuanced response. For example, would it be ok to change DNA to “produce” healthier children (i.e. correct lethal genetic defects using genome editing) without necessarily “producing” smarter and more athletic children?

Conflating health, intelligence and athleticism into one question makes it difficult to ascertain how the public feels about using genome editing to help children survive versus using it to make kids run faster.

Most participants did not think they would want to eat lab grown meat or use brain implants to improve their mental capacity but roughly half of them seemed fine with using driverless cars.


Lab grown meat


When asked about what futuristic invention they would like to own, younger participants seemed most excited about time travel and other travel gadgets (flying cars, bikes and space crafts), whereas older participants wanted to inventions to prolong life or cure diseases.

What do people want

I was a bit surprised that this final question did not elicit responses such as inventions that would help reduce or reverse global warming and pollution or inventions that could remedy world hunger and the global scarcity of resources. Maybe it has to also do with how the question was phrased. Here is the actual question:

Science fiction writers have always imagined new inventions that change the world of the future. How about you? If there was one futuristic invention that you could own, what would it be?


Here is the actual data (PDF) of the responses people gave:


Improved health and longevity/Cure for diseases                        9%

Time machine/Time travel                                                           9%

Flying car/Flying bike                                                                6%

Personal robot/Robot servants                                                 4%

Personal space craft                                                                 4%

Self-driving car                                                                         3%

Teleporter/Teleportation/Transporter                                           3%

World peace/Stop wars/Improved understanding/Better planet     2%

New energy source/efficient cars/other environment                    2%

Invention to make household tasks easier                                   1%

Ability to live forever/Immortality                                                  1%

Jetpack                                                                                    1%

Money/Scheme to get rich/Ability to read future                         1%

Brain implant/Improve memory                                                   1%

Hovercar/Hoverboard                                                                1%

Hologram/Holodeck                                                                  *

Remote communications (via device or ESP)                              *

Other                                                                                        9%

None/Nothing/Not interested in futuristic inventions                     11%


The science fiction reference in the question may have prompted participants to think of technologies described in sci-fi novels and movies. Perhaps the majority of respondents did not think that world peace or climate-control could be achieved with specific sci-fi style inventions. Or perhaps the participants did not realize that climate change, global scarcity of food or other resources and violent conflicts are some of the biggest threats that humankind has ever faced.

Many of the responses to this final question tend to fall into the category of “how could my life become more convenient“, such as using personal robots and flying cars. But will these conveniences even matter if we cannot curb the major threats that our planet faces?

Synthetic Biology: Engineering Life To Examine It

Two scientific papers that were published in the journal Nature in the year 2000 marked the beginning of engineering biological circuits in cells. The paper “Construction of a genetic toggle switch in Escherichia coli” by Timothy Gardner, Charles Cantor and James Collins created a genetic toggle switch by simultaneously introducing an artificial DNA plasmid into a bacterial cell. This DNA plasmid contained two promoters (DNA sequences which regulate the expression of genes) and two repressors (genes that encode for proteins which suppress the expression of genes) as well as a gene encoding for green fluorescent protein that served as a read-out for the system. The repressors used were sensitive to either selected chemicals or temperature. In one of the experiments, the system was turned ON by adding the chemical IPTG (a modified sugar) and nearly all the cells became green fluorescent within five to six hours. Upon raising the temperature to activate the temperature-sensitive repressor, the cells began losing their green fluorescence within an hour and returned to the OFF state. Many labs had used chemical or temperature switches to turn gene expression on in the past, but this paper was the first to assemble multiple genes together and construct a switch which allowed switching cells back and forth between stable ON and OFF states.


The same issue of Nature contained a second land-mark paper which also described the engineering of gene circuits. The researchers Michael Elowitz and Stanislas Leibler describe the generation of an engineered gene oscillator in their article “A synthetic oscillatory network of transcriptional regulators“. By introducing three repressor genes which constituted a negative feedback loop and a green fluorescent protein as a marker of the oscillation, the researchers created a molecular clock in bacteria with an oscillation period of roughly 150 minutes. The genes and proteins encoded by the genes were not part of any natural biological clock and none of them would have oscillated if they had been introduced into the bacteria on their own. The beauty of the design lay in the combination of three serially repressing genes and the periodicity of this engineered clock reflected the half-life of the protein encoded by each gene as well as the time it took for the protein to act on the subsequent member of the gene loop.

Both papers described the introduction of plasmids encoding for multiple genes into bacteria but this itself was not novel. In fact, this has been a routine practice since the 1970s for many molecular biology laboratories. The panache of the work lay in the construction of functional biological modules consisting of multiple genes which interacted with each other in a controlled and predictable manner. Since the publication of these two articles, hundreds of scientific papers have been published which describe even more intricate engineered gene circuits. These newer studies take advantage of the large number of molecular tools that have become available to query the genome as well as newer DNA plasmids which encode for novel biosensors and regulators.

Synthetic biology is an area of science devoted to engineering novel biological circuits, devices, systems, genomes or even whole organisms. This rather broad description of what “synthetic biology” encompasses reflects the multidisciplinary nature of this field which integrates ideas derived from biology, engineering, chemistry and mathematical modeling as well as a vast arsenal of experimental tools developed in each of these disciplines. Specific examples of “synthetic biology” include the engineering of microbial organisms that are able to mass produce fuels or other valuable raw materials, synthesizing large chunks of DNA to replace whole chromosomes or even the complete genome in certain cells, assembling synthetic cells or introducing groups of genes into cells so that these genes can form functional circuits by interacting with each other. Synthesis in the context of synthetic biology can signify the engineering of artificial genes or biological systems that do not exist in nature (i.e. synthetic = artificial or unnatural), but synthesis can also stand for integration and composition, a meaning which is closer to the Greek origin of the word.  It is this latter aspect of synthetic biology which makes it an attractive area for basic scientists who are trying to understand the complexity of biological organisms. Instead of the traditional molecular biology focus on studying just one single gene and its function, synthetic biology is engineering biological composites that consist of multiple genes and regulatory elements of each gene. This enables scientists to interrogate the interactions of these genes, their regulatory elements and the proteins encoded by the genes with each other. Synthesis serves as a path to analysis.

One goal of synthetic biologists is to create complex circuits in cells to facilitate biocomputing, building biological computers that are as powerful or even more powerful that traditional computers. While such gene circuits and cells that have been engineered have some degree of memory and computing power, they are no match for the comparatively gigantic computing power of even small digital computers. Nevertheless, we have to keep in mind that the field is very young and advances are progressing at a rapid pace.

One of the major recent advances in synthetic biology occurred in 2013 when an MIT research team led by Rahul Sarpeshkar and Timothy Lu at MIT created analog computing circuits in cells. Most synthetic biology groups that engineer gene circuits in cells to create biological computers have taken their cues from contemporary computer technology. Nearly all of the computers we use are digital computers, which process data using discrete values such as 0’s and 1’s. Analog data processing on the other hand uses a continuous range of values instead of 0’s and 1’s. Digital computers have supplanted analog computing in nearly all areas of life because they are easy to program, highly efficient and process analog signals by converting them into digital data. Nature, on the other hand, processes data and information using both analog and digital approaches. Some biological states are indeed discrete, such as heart cells which are electrically depolarized and then repolarized in periodical intervals in order to keep the heart beating. Such discrete states of cells (polarized / depolarized) can be modeled using the ON and OFF states in the biological circuit described earlier. However, many biological processes, such as inflammation, occur on a continuous scale. Cells do not just exist in uninflamed and inflamed states; instead there is a continuum of inflammation from minimal inflammatory activation of cells to massive inflammation. Environmental signals that are critical for cell behavior such as temperature, tension or shear stress occur on a continuous scale and there is little evidence to indicate that cells convert these analog signals into digital data.

Most of the attempts to create synthetic gene circuits and study information processing in cells have been based on a digital computing paradigm. Sarpeshkar and Lu instead wondered whether one could construct analog computation circuits and take advantage of the analog information processing systems that may be intrinsic to cells. The researchers created an analog synthetic gene circuit using only three proteins that regulate gene expression and the fluorescent protein mCherry as a read-out. This synthetic circuit was able to perform additions or ratiometric calculations in which the cumulative fluorescence of the mCherry was either the sum or the ratio of selected chemical input concentrations. Constructing a digital circuit with similar computational power would have required a much larger number of components.

The design of analog gene circuits represents a major turning point in synthetic biology and will likely spark a wave of new research which combines analog and digital computing when trying to engineer biological computers. In our day-to-day lives, analog computers have become more-or-less obsolete. However, the recent call for unconventional computing research by the US Defense Advanced Research Projects Agency (DARPA) is seen by some as one indicator of a possible paradigm shift towards re-examining the value of analog computing. If other synthetic biology groups can replicate the work of Sarpeshkar and Lu and construct even more powerful analog or analog-digital hybrid circuits, then the renaissance of analog computing could be driven by biology.  It is difficult to make any predictions regarding the construction of biological computing machines which rival or surpass the computing power of contemporary digital computers. What we can say is that synthetic biology is becoming one of the most exciting areas of research that will provide amazing insights into the complexity of biological systems and may provide a path to revolutionize biotechnology.

ResearchBlogging.orgDaniel R, Rubens JR, Sarpeshkar R, & Lu TK (2013). Synthetic analog computation in living cells. Nature, 497 (7451), 619-23 PMID: 23676681





An earlier version of this article was first published here on the 3Quarksdaily blog.

Should Doctors ‘Google’ Their Patients?

Here is an excerpt from my latest post on the 3Quarksdaily blog:


Beware of what you share. Employers now routinely utilize internet search engines or social network searches to obtain information about job applicants. A survey of 2,184 hiring managers and human resource professionals conducted by the online employment website revealed that 39% use social networking sites to research job candidates. Of the group who used social networks to evaluate job applicants, 43% found content on a social networking site that caused them to not hire a candidate, whereas only 19% found information that that has caused them to hire a candidate. The top reasons for rejecting a candidate based on information gleaned from social networking sites were provocative or inappropriate photos/information, including information about the job applicants’ history of substance abuse. This should not come as a surprise to job applicants in the US. After all, it is not uncommon for employers to invade the privacy of job applicants by conducting extensive background searches, ranging from the applicant’s employment history and credit rating to checking up on any history of lawsuits or run-ins with law enforcement agencies. Some employers also require drug testing of job applicants. The internet and social networking websites merely offer employers an additional array of tools to scrutinize their applicants. But how do we feel about digital sleuthing when it comes to relationship that is very different than the employer-applicant relationship – one which is characterized by profound trust, intimacy and respect, such as the relationship between healthcare providers and their patients?

The Hastings Center Report is a peer-reviewed academic bioethics journal which discusses the ethics of “Googling a Patient” in its most recent issue. It first describes a specific case of a twenty-six year old patient who sees a surgeon and requests a prophylactic mastectomy of both breasts. She says that she does not have breast cancer yet, but that her family is at very high risk for cancer. Her mother, sister, aunts, and a cousin have all had breast cancer; a teenage cousin had ovarian cancer at the age of nineteen; and that her brother was treated for esophageal cancer at the age of fifteen. She also says that she herself has suffered from a form of skin cancer (melanoma) at the age of twenty-five and that she wants to undergo the removal of her breasts without further workup because she wants to avoid developing breast cancer. She says that her prior mammogram had already shown abnormalities and she had been told by another surgeon that she needed the mastectomy.

Such prophylactic mastectomies, i.e. removal of both breasts, are indeed performed if young women are considered to be at very high risk for breast cancer based on their genetic profile and family history. The patient’s family history – her mother, sister and aunts being diagnosed with breast cancer – are indicative of a very high risk, but other aspects of the history such as her brother developing esophageal cancer at the age of fifteen are rather unusual. The surgeon confers with the patient’s primary care physician prior to performing the mastectomy and is puzzled by the fact that the primary care physician cannot confirm many of the claims made by the patient regarding her prior medical history or her family history. The physicians find no evidence of the patient ever having been diagnosed with a melanoma and they also cannot find documentation of the prior workup. The surgeon then asks a genetic counselor to meet with the patient and help resolve the discrepancies. During the evaluation process, the genetic counselor decides to ‘google’ the patient.

The genetic counselor finds two Facebook pages that are linked to the patient. One page appears to be a personal profile of the patient, stating that in addition to battling stage four melanoma (a very advanced stage of skin cancer with very low survival rates), she has recently been diagnosed with breast cancer. She also provides a link to a website soliciting donations to attend a summit for young cancer patients. The other Facebook page shows multiple pictures of the patient with a bald head, suggesting that she is undergoing chemotherapy, which is obviously not true according to what the genetic counselor and the surgeon have observed. Once this information is forwarded to the surgeon, he decides to cancel the planned surgery. It is not clear why the patient was intent on having the mastectomy and what she would gain from it, but the obtained information from the Facebook pages and the previously noted discrepancies are reason enough for the surgeon to rebuff the patient’s request for the surgery.


If you want to learn more about how ethics experts analyzed the situation and how common it is for psychologists enrolled in doctoral programs to use search engines or social networking sites in order to obtain more information about their patients/clients, please read the complete article at