Thursday, December 26, 2013

What's Vitamin D, Precious?

The latest installment of The Hobbit trilogy has come to theaters. In honor of Bilbo's return to the screen I thought I would do a post about some Middle Earth science.

A new article by Joseph and Nicholas Hopkinson, published in The Medical Journal of Australia, asks an interesting question: Why do bad guys always lose? The villain might score some small victories in the beginning, the good guys will stumble along the way, but ultimately the hero will achieve victory in the end. It is a strikingly consistent feature of narratives whether they are on the page, stage, or screen. Most agree that this trope can be attributed to conventions about morality and the necessity of the happy ending. However, the authors of this paper posit that there may be other major factors that lead to the defeat of evildoers: their aversion to sunlight and their poor diet. These factors lead may lead to a vitamin D deficiency that reduces martial prowess.

Vitamin D is referred to as the “sunshine vitamin.” It is a fat-soluble vitamin that acts as a steroid hormone. It is produced by the skin in response to ultraviolent light (sunlight). It also occurs naturally in a few foods such as egg yolks, fish oils, and cheese. Vitamin D is essential for strong bones because of its role in calcium metabolism, and it has immune-modulating functions. Vitamin D deficiency (VDD) can result in rickets, osteomalacia, skeletal muscle weakness, and a susceptibility to other conditions ranging from multiple sclerosis to tuberculosis and accelerated lung function decline.

The authors first conducted a literature search on “imaginary populations” and “vitamin D” that returned no publications, letting them know that they were on to a novel concept. Then they performed a pilot study using textual analysis to extract data relating to diurnal habits, dwelling, light exposure and diet from The Hobbit by J. R. R. Tolkien. Next, they identified protagonists as good or evil and victorious or defeated on binary scales by consensus. These characters were then scored on (1) sun exposure rated from 3=lots to 0=none, (2) the mention of a vitamin D-containing diet item with 0=no mention and 1=mention, and (3) summing these to give a vitamin D score that was related to victoriousness by unpaired t tests.

Let’s break it down by type:

The Good Guys -

As a hobbit, Bilbo Baggins lives in the ground. However, his hobbit hole has lots of windows and he often smokes his pipe in the sun overlooking his garden. He has a varied diet that includes cake, tea, seed cake, ale, porter, red wine, raspberry jam, mince pies, cheese, pork pie, salad, cold chicken, pickles and apple tarts. And this is simply what he offers the dwarves that invade his household at the beginning of the story. The dwarves are described as a race that likes the dark, but they do spend a lot of time above ground in at least the first part of their journey to the Lonely Mountain. And, as their dinner at Bilbo’s house shows, they eat a variety of food with gusto! As wizards may frequently travel, they will also receive quite a bit of sunlight. And although their diet is not specifically described, Galdalf is often seen appreciating the food and beverage that goes along with any social endeavor he may observe or participate in. Elves, both high and wood, “feast merrily in clearings in the woods” and also receive high vitamin D scores.

The Bad Guys -

One of the first unsavory creatures that the good guys come across are trolls. Trolls naturally avoid sunlight as it turns them into stone. They live on an exclusively mutton diet, are strong but stupid, and consume jugs of “good drink” that further befuddle their wits. In one of the best scenes (in my humble opinion), Bilbo meets Gollum. Gollum lives in the deep dark of the Misty Mountains. His diet consists of a lot of raw blind fish which may be good, but as all fish do not contain vitamin D it remains unclear as to the advantages of this item. He also eats goblins, on the rare times that they fall into his domain. And, although goblins may also eat some fish (especially the Great Goblin), their proclivity for the dark also gives them a low vitamin D score. Spiders (e.g. Shelob) dwell in the dark and ambush their prey, the vitamin D content depending on what wanders into their territory. And finally, Smaug the dragon lives under his stolen mountain coming out at night to eat people (favoring maidens, but sometimes also ponies and Lake-men).

The authors' initial textual analysis supported their hypothesis that the success of the good guys may be assisted, to some extent, by the poor diet and lack of sunlight experienced, and even preferred, by the bad guys. Their scoring results show the mean vitamin D score of the victorious characters to be significantly higher than the non-victorious. However, they note that “the absolute concordance between goodness and victoriousness precludes an assessment of this as an independent effect.”

It is important to note that a few things were not taken into account for the purposes of this study. The first are the health issues surrounding smoking which is associated with skeletal muscle dysfunction. Another is the taxanomical classification of creatures (i.e. mammal vs. bird vs. arachnid). In humans, vitamin D is produced by a UVB-induced conversion of 7-dehydrocholesterol into vitamin D. The vitamin then undergoes two hydroxylations in the body for activation. As the physiology of the creatures of Middle Earth is more obscure, it is not known if they produce vitamin D in a similar way. As this is a pilot study, the authors also only look at The Hobbit and so do not include any details on diet and habitat that are further detailed in the other works of Middle Earth. Perhaps future investigations will include these novels and even some other well known bad guys from some of our other favorite tales. I look forward to it!

ResearchBlogging.orgJoseph A Hopkinson, & Nicholas S Hopkinson (2013). The hobbit — an unexpected deficiency The Medical Journal of Australia, 199, 805-806 DOI: 10.5694/mja13.10218

More about vitamin D and VDD:

ResearchBlogging.orgRathish Nair, & Arun Maseeh (2012). Vitamin D: The “sunshine” vitamin J Pharmacol Pharmacother, 3 (2), 118-126 DOI: 10.4103/0976-500X.95506

(image via the LOTR Wiki) 

Wednesday, December 25, 2013

Scientifically Accurate Santa

The trend of turning your favorite characters, icons, and historical figures into their scientifically accurate (and often rather crude) versions continues with Scientifically Accurate Santa.

Merry Christmas (or other applicable holiday)!

Thursday, November 28, 2013

Wednesday, November 27, 2013

Tips For Talking About Climate Change

Working in science automatically means you know everything about science. Duh. You're like one of those scientists we see on TV. So when you attend a large family gathering, Thanksgiving for example, you may be expected to explain a controversial topic. You know, since your the expert. The biggest one that people like to ask about, but have already have opinions on, is climate change. But there is a difference between talking at someone and having an effective conversation. An article over at the Environmental Defense Fund website gives you some tips to do just that, no matter who you run into. Their article is so well done that I'm just going to copy it as is, and a link to the original can be found at the bottom of the post.

"Climate change has become one of those divisive, polarizing issues that confound our political system. It's often hard to even have a civil conversation with folks who disagree, even with close relatives or friends.

 But it is clear that the climate crisis has arrived. And the key to solving it is educating those around us.

Chances are your friends and family fall into one of the following six categories:
  • Alarmed Aunt Anna 
  • Concerned Grandpa Christopher 
  • Cautious Cousin Charlie 
  • Disengaged Grandma Denise 
  • Doubtful Brother David 
  • Dismissive Aunt Debbie
The way people in each category respond to the climate issue varies. If you want to have an effective conversation, the way you talk about climate with different types of people should adjust accordingly.

Alarmed Aunt Anna & Concerned Grandpa Christopher

They believe the science is real, but may doubt our ability to solve the climate crisis.

Here are a few points that may inspire them to keep up the fight:

  • California—the 8th largest economy in the world—has implemented the world's most ambitious climate action plan. 
  • At the national level, the EPA is starting to regulate climate pollution using its existing authority under the Clean Air Act. 
  • The renewable energy industry is growing exponentially—in fact, the clean energy economy is growing twice as fast as the rest of the economy, and we have enough potential wind and solar energy in the U.S. to power our economy 100 times over.
Trump Card: Yes, this is challenging. Yes, it will take time to rebuild support for national climate action. But what choice do we have? There is no time to waste, and we need to act now.

Cautious Cousin Charlie, Disengaged Grandma Denise and Doubtful Brother David 

These folks probably (and wrongly) believe that there isn't a true consensus on the science of climate change. We know that's not true, but don't go on the attack! They tend to be more open to changing their minds if they are engaged in effective conversation. 

Here are some basic facts that they'll find engaging:
  • Carbon dioxide is a heat-trapping gas, and that's generally a very good thing. Without greenhouse gases, every night when the sun sets, temperatures would immediately plunge to frigid levels. 
  • But, we are now emitting 9 billion tons of CO2 into the atmosphere every year, and CO2 levels have increased by about a third since the industrial revolution. If we don't reduce emissions, we could more than double the level of CO2 in the atmosphere over this century. 
  • Already, food growing patterns are changing, seasons are coming earlier, water resources are strained and the number of natural disasters in the U.S. has more than quadrupled in the last 50 years.
Trump Card: You don't have to accept all the science. But, if you had a health condition and 98 out of 100 doctors agreed on the diagnosis, would you base your treatment on the views of the other two?

Dismissive Aunt Debbie

The truth is, there is almost no chance of changing her mind, and it's probably not worth trying unless you like banging your head against a wall. Ironically, research shows that the more facts you try to present, the less likely she will be to agree. However, even Dismissive Aunt Debbie will be open to arguments about stimulating the economy and protecting national security.

Try steering the conversation towards those issues:
  • America needs to rebuild. Did you know the clean energy sector creates 3 times as many jobs as the fossil fuel sector? We can't afford to pass up those jobs. 
  • Other countries are taking advantage of the economic stimulation that comes with climate action. China is testing carbon cap-and-trade markets in an area encompassing 250 million people. The U.S. needs to stay competitive. 
  • America's billion-dollar-a-day dependence on oil from hostile nations directly funds our most dangerous enemies, putting guns and bullets into their hands and putting our soldiers in danger. It is time for America to stand strong on its own independent and in control of our energy future.
Trump Card: Whether climate change is real or not, the benefits of a clean energy economy are undeniable. Not only will we rid ourselves of dangerous pollution that can make us sick and even cause deaths we can finally be energy independent. What's the downside?"

Good luck!

The original can be found at EDF's page "Talking Turkey About Climate: Without starting a food fight"

All of the images found in this post are part of the original EDF article.

Tuesday, November 26, 2013

A Better Thanksgiving Through Chemistry

Here in the U.S. it's almost Thanksgiving. Planning to make a big meal? Here are some great cooking tips and the chemistry that makes them work.

Monday, November 25, 2013

Going to the Movies: The Seat Choice Dilemma (Part 3)

Welcome to Part 3, the final step in our science-tastic trip to the movie theater. I’d suggest checking out Part 1 and Part 2 as so far, you've purchased your expensive ticket, wondered at high concession prices, agonized over which size popcorn to buy, and learned how that choice will ultimately determine how much you will eat. Now you are ready to go find a seat for the show! You pick up your concessions from the counter, figure out how to carry them in such a way as to not spill anything and yet still be able to hand your ticket to be torn, walk down the hallway to find your theater number, go down the dark felt-covered tunnel, and then stand at the bottom of the stairs contemplating which row to sit in.

Let’s start by asking if where you sit will really affect what you see? There is an older, interesting piece written by James Cutting in 1986 that looks at the shape and psychophysics of cinematic spaces. Probably haven’t heard the term psychophysics, right? I know I hadn't. Well, it is a branch of psychology that’s concerned with how physical processes (the intensity of stimulants like vision and sound) affect your sensations, perceptions, and mental processes. Basically, a mind-body problem. Movies have the capacity to draw us in such that we get “lost” in them; we project ourselves into a new space and time, one that the filmmakers have created for us. The high picture quality and larger screens have been shown to help give us viewers the impression of “being there.” Dimming the lights dims out the real world, the large screen fills our optic array, the smoothness of the frame rate (flicker threshold) allows the images we see to become lifelike, and the pacing of scenes and cuts can enhance our emotions. However, a movie is ultimately an optical projection and it would be logical to think that where you sit may matter in how you see the movie (geometry, distortions, etc.). But in his paper, Cutting describes why this isn't so. He uses static art as an example, asking you to look at a picture from different angles. Then he explains that affine and perspective transformations affecting the look of rigidity of objects on the screen is actually very difficult for people to discern (what he terms La Gournerie’s paradox). In search of why this is so, he goes through a lot of history, and geometry, and equations, and well, I’m not even gonna touch those. But essentially, he comes down to two possibilities: (1) our brains compensate for and rectify any distortions we see by using information about screen slant, and (2) we preserve information about the transformations we see to ensure our perception remains unperturbed. So when you’re standing at the bottom of those stairs looking around for a seat, know that where you sit doesn't really matter in how you view the movie. Your brain’s got it covered.

Choosing a seat, however, is a conscious choice. Like any other choice it is influenced by the characteristics of the item, particularly (and especially in this case), the location. Let’s start simple and consider our lateralized tendencies, a.k.a. which side of the theater you like to sit on, right or left. A study published in Cortex in 2000 looked at handedness as a predictor of behavioral asymmetries. Previous studies of cerebral organization show that the brain’s right hemisphere shows a considerable advantage for face recognition, spatial stimuli, and emotions. With this knowledge, this study asked if these directional biases are reflected in the seat choices we make at the cinema. The researchers screened and interviewed participants for handedness (right, left, mixed). Then they gave them maps of five theaters, each differing in the location of the entries/exits and aisles, and dividing seats into equal parts with the middle seats marked as sold out. They found a preference for right positions when watching movies in the three handedness classes underlying a left-directed perceptual bias, which they found to be most evident in right handers and decreased progressively from them to the left handers. The author postulates that this is because the leftward orientation of attention fosters the activation of the right hemisphere cultivated through the learned reflexes of previous biases. A study published in Laterality in 2006 also looked at this seat-side preference, also by asking participants to look at various maps of theater seating, this time altering screen location. This study confirmed the overall right side seat preference, with a stronger preference if the screen were at the top or right of the map, and additional preference for seats at the back of the cinema. However, they found that the turn at the entrance to the theater to perfectly correlate with the chosen seat-side. A result that could reflect general turning habits (I really hope that someone has termed this the Zoolander Hypothesis).

I think we can all agree that handedness is a rather simple way to look at something. There is obviously more going on here. A paper, this time in Applied Cognitive Psychology in 2010, added the role of motivation to their study. They wanted to know if people highly motivated to see a movie would choose the right side of the theater, since these seats are better suited to processing information from the left visual field and therefore direct access to the visual and emotional side of the brain (right hemisphere). In their first experiment they told all of the participants that a movie was highly recommended and half of them were further advised that they would rather avoid watching the movie because the story was sad and depressing (thereby negating the positive motivation of the recommendation while also giving negative motivation). Then they asked the participants to choose a seat from a seating chart. Knowing that some dark or depressing stories often achieve immense commercial success (e.g. The Dark Knight), they also conducted an experiment where they reversed the status of the negative emotional content. They found that when right-handers were positively motivated they chose seats on the right side. This bias disappeared when they were negatively motivated. This held true even when a depressing movie was spun a positive. Non-right-handers did not exhibit such lateral biases regardless of experimental condition.

Personally, I’m a middle theater, middle seat kind of person. That particular bias hasn't really been addressed by the studies above, in fact they grey-out the middle seats to force people to choose a side. This is what Rodway et al. considered when they conducted their study in 2012. They decided to compare the right-side preference to the center-stage effect. The latter suggests that people’s choice decisions are guided by the perception that good, important people occupy the middle. They examined this closer in a first experiment where they presented people with five identical pictures (of random regular things like butterflies or waterfalls) arranged in a line and asked them to pick their most and least preferred items. The results showed a significant trend for people to select their most preferred item in the middle position, a result not seen when choosing the least preferred item. A second experiment looked at the array format to see if the center tendency extended to vertically arranged items, knowing that top positions are generally associated with positive attributes and vice versa. As with the first experiment, participants chose items in the center rather than the top or bottom, adding robustness to this center-stage theory. A final experiment wanted to see if these preferences are associated with real items rather than just pictures. As with the other two, this experiment showed a preference for center items, although there was also a significant reduction for the items at the lowest two locations. Did they actually go into a theater and ask people about seats? Well no. But I included this study because I have yet to come across a paper that has asked this, and being a center-seater, I thought it was a rather important aspect to the whole seat-choice dilemma.

These studies all look at a simple choice aspects, which, admittedly, is a good place to start. However, I think I would like to read about how group size matters. You know you ask your friends where they want to sit, right? Or what about how people don’t like to sit next to each other? What about choosing a seat in a theater where many of the seats are already taken? If your preferred seats are gone, where do you sit?

Well, that’s all for our trip to the cinema. Now that you've found your seat, enjoy the show!

ResearchBlogging.orgJames E. Cutting (1986). The shape and psychophysics of cinematic space Behavior Research Methods,, Instruments, & Computers, 18 (6), 551-558 DOI: 10.3758/BF03201428

ResearchBlogging.orgGeorge B. Karev (2000). Cinema Seating in Right, Mixed and Left Handers Cortex, 36, 747-752 DOI: 10.1016/S0010-9452(08)70550-1

ResearchBlogging.orgMatia Okubo (2010). Right Movies on the Right Seat: Laterality and Seat Choice Applied Cognitive Psychology, 24, 90-99 DOI: 10.1002/acp.1556

ResearchBlogging.orgPaul Rodway, Astrid Schepman, and Jordana Lambert (2012). Preferring the One in the Middle: Further Evidence for the Centre‐stage Effect Applied Cognitive Psychology, 26, 215-222 DOI: 10.1002/acp.1812

ResearchBlogging.orgPeter Weyers, Annette Milnik, Clarissa Muller, & Paul Pauli (2006). How to choose a seat in theatres: Always sit on the right side? Laterality, 11 (2), 181-193 DOI: 10.1080/13576500500430711

(image via The Expert Institute)

Wednesday, November 13, 2013

Going to the Movies: The Story of a Popcorn Pit (Part 2)

Welcome to Part 2 of my journey to the movie theater. This will make sense if you haven’t read Part 1, but to enjoy the full impact of this visite du cinéma, I suggest you read both. If ya just don’t wanna then here’s a summary: (1) movie tickets are expensive, (2) as far as I can tell, nobody has really done a direct study of why, (3) economists try to explain why all movies cost the same through their “uniform pricing for differentiated goods” theory, (4) as it turns out, variable or differentiated pricing is probably better, (5) concessions are expensive too, (6) theaters get all of this “consumer surplus,” (7) channels of ticket distribution, group size, and theater characteristics affect concession sales, and (8) theaters get as much money as possible from people willing to pay it.

So far, we've made it past the door with our high priced tickets, and we stood in front of the concession stand wondering why those prices are also so high. Let’s say that you decide to take the monetary plunge and buy some concessions. You look over the candy, the nachos, the questionable looking hot dogs and you decide to go with popcorn. You look at the sizes of the containers, perhaps ask to see one a little closer, and go with the medium. But wait! The large is only 25 cents more! Okay, so you go with the large. I mean, if you are going to pay 5 dollars for popcorn then there might as well be a lot of it right?

What are the effects of ordering that 18 cup bucket of inflated food? It is slathered in a buttery goodness that makes it pretty frickin’ yummy, but are you really going to eat all of that? Most people tend to think that how much they eat is based on the taste of the food. Studies in the absence of environmental cues have largely shown this to be true. That makes sense if you think about it. When you have no distractions you can concentrate on the flavor of your food. However, the movie theater is the opposite of a distraction-free environment.

In 2001 Wansink and Park published a study where they gave 161 moviegoers free popcorn and soft drinks. The same popcorn was given in either a medium (120g) or large (240g) container, with before and after weights taken to see how much was eaten. Then they asked the participants to fill out a questionnaire after their movie about the taste of the popcorn. The results showed that people who rated their popcorn as tasty ate 49 percent more if it was in a large container than a medium one. Surprisingly, people who rated the taste of their popcorn as unfavorable still ate 61 percent more if it was put in a larger container. A related study from 2005, also headed by Wansink, looked at how container size can influence food intake, even when it is less palatable. Again they randomly gave 158 moviegoers either a medium or large container of popcorn, weighing the containers before and after the movie. But this time they purposefully changed the taste of the popcorn, giving participants either fresh or stale (14 days old…eww). Similar to the first study, the results showed that moviegoers ate 45.3 percent more popcorn from a large container than from a medium container when the popcorn was fresh. And while the moviegoers with stale popcorn negatively described their food as “stale,” “soggy,” or “terrible,” they still ate 33.6 percent more if they were given large containers than if they were given medium containers.

A more recent study published in the journal Appetite also looked to see if people consumed more food with larger containers, this time focusing on portion size vs. container size. They served M&M’s for free to 88 undergraduate students watching a 22 minute long TV show. Participants were served either a medium portion of M&M’s in a small container, a medium portion in a large container, or a large portion in a large container. Given the same amount of food, people with the large containers ate 129 percent (199 kcal) more than people with the medium containers, and when given a larger portion size they ate 97 percent more. Basically, that large bucket of food stimulates your food intake over and above the portion size. So perhaps that large popcorn you purchased wasn't the best idea.

But fear not! There is actually an up-side. You know how you eat most of your popcorn before the movie even starts, during the ads and previews? Well, an article published online this year in the Journal of Consumer Psychology looked at how “oral interference” (i.e. eating) affects the impact of those ads on people’s brand attitudes and choices. In their experiments, they gave free popcorn and chewing gum to participants and asked them to watch a movie preceded by a series of real but foreign commercials (so they hadn't seen them before), asking them to eat as soon as the commercials started. Then one week later they assessed the participants and a control group (no free popcorn or gum) for their purchasing choices. The researchers found that the control group spent more money and had a preference for the brands they saw in the commercials. The participants that ate during the commercials showed no such preferences. Yeah! Pop blocked!

I’ll see you next week for the last, and final, part of this series. Happy eating!

ResearchBlogging.orgB. Wansink and S.B. Park (2001). At the movies: how external cues and perceived taste impact consumption volume Food Quality and Preference, 12, 69-74 DOI: 10.1016/S0950-3293(00)00031-8

ResearchBlogging.orgB. Wansink and J. Kim (2005). Bad Popcorn in Big Buckets: Portion Size Can Influence Intake as Much as Taste Journal of Nutrition Education and Behavior, 37 (5), 242-245 DOI: 10.1016/S1499-4046(06)60278-9

ResearchBlogging.orgD. Marchiori, O. Corneille, & O. Klein (2012). Container size influences snack food intake independently of portion size Appetite, 58, 814-817 DOI: 10.1016/j.appet.2012.01.015

ResearchBlogging.orgS. Topolinski, S. Lindner, & A. Freudenberg (2013). Popcorn in the cinema: Oral interference sabotages advertising effects Journal of Consumer Psychology DOI: 10.1016/j.jcps.2013.09.008

Just for interest’s sake, an interesting article from the Smithsonian about the history of popcorn and the cinema: "Why Do We Eat Popcorn at the Movies?"

(image via

Wednesday, November 6, 2013

If TV Science Was More Like Real Science

Ahhhh....the wonder of TV science! Where you have a degree that makes you an expert in all scientific and engineering subdisciplines as well as the ability to get your hands on equipment that solves all your problems without error. You never see anyone frustrated that their PCR yielded nothing.

Sunday, November 3, 2013

Going to the Movies: The Story of a Money Pit (Part 1)

I love movies. Love to sit and watch them at home. Love to have movie nights with my friends. Love going to see them at the theater. On that last one, I think we can all agree on one thing: movie theaters are money pits. Essentially you just walk up to their front door and start throwing all of your money at them. You bitch and moan but you accept it. You knew before you ever left your house that you were going to spend an exorbitant amount of cash for a load of calories and an unknown experience. With my frequent trips to the theater and the resulting cash outflow I got to wondering why. In an attempt to answer this I took a step-by-step approach, looking at a typical trip to the cinema.

According to the National Association of Theater Owners, the average cost of a movie ticket in the U.S. rose to from $7.96 in 2012 to $8.38 in 2013. Granted, this rise is due, in part, to rising surcharges for 3D, IMAX films, and “luxury cinemas;” it is also indicative of an overall rise in movie ticket prices. When I fired up a few of my favored scholarly search engines, I found literature mostly on the movie industry itself but a surprising lack of literature on movie ticket prices, regional differences, surcharges, etc. There are a few papers that address movie ticket prices in terms of economic theory, but that’s kinda it. These papers look at cost-based explanations for why there is one price for all movies, all the time. It is what economists call “uniform pricing for differentiated goods,” which is usually compared to a price differentiated or variable pricing system.  Sure, there are senior and student discounts as well as matinee rates (so called “third degree price discrimination”), but in general, each moviegoer pays the same price for all movies at any time. Theater quality, seat location, quality of the movie, etc. – same price.

A paper by Rosen and Rosenfield in 1997 argues for an optimal two-part pricing system where consumers with the greatest demand buy higher priced tickets to earlier performances, a strategy that was propositioned around the same time by Universal CEO Edgar Bronfman. A scheme that was obviously not adopted. Papers published in 2001 and 2007 by Orbach and Einav examine and support the argument that theaters could benefit from price differentiation across movies and show times. However, they point out that uniform pricing may persist because consumers may perceive variable pricing as unfair, that the short life cycles of movies make it difficult to adjust prices, and the difficulties continue between distributors and theater owners. The latter is examined in more detail in a publication in Marketing Science by Eliashberg, Elberse, and Leenders that reviews the process of movie making and distribution. In the Exhibition section of their paper, they describe the contractual arrangements between distributors and cinemas and pay special attention to the relative powers of these two parties. The distributors’ power lies in the expected success of a particular movie and the amount of promotional support they are willing to commit. The theaters’ power lies in its location and relative shortage (or surplus) of available screens. Overlying all of this is the uncertainty of demand and it filters down into ticket prices. These prices are a dance between the distributors and the theaters. Theaters often prefer lower ticket prices to compete more effectively with other theaters. This has the knock-on effects of increasing attendance and revenues from concessions. Naturally, distributors want high prices and have even actively sought, although largely unsuccessfully, to increase their revenues through variable price structuring. To sum up, how much you pay at the box office essentially comes down to how consumers value goods, the legal constraints on the relationships between distributors and theaters, and the negotiations that occur between these parties.

So now you’ve purchased a ticket which is considered low by both the distributers and the theaters. Okay, we’ll go with that. Next, you walk inside to hear the pop-pop-pop of the popcorn machine, the whoosh of the soda dispenser, the lights of the menus and candy displays, and the oh-so-mouthwateringly good smell of butter. Yep, you are faced with the concession stand and the high prices that go along with it. You know those “low” ticket prices the theater owner has negotiated for you? They are offset by the sale of these concessions, revenues that are not shared with the movie distributors. Also, most theaters bar you from bringing your own food and exploit your immobility by charging high prices for their products. So how likely are you to buy those tempting confections? A paper published in Economic Inquiry back in 1991 looks at these high prices, pointing out that “if all movie viewers ate popcorn at the movies and ate the same amount, the question of pricing at the concession stand would be of little interest. The only thing that would matter would be the combined price of the ticket and the [refreshment].” But in actuality only a fraction of customers purchase concessions and by charging a high price the theater is able to extract consumer surplus.

A study by Gil and Hartmann in 2007 took a look at the role and determinants of concession sales using data from 22 Spanish theaters in 19 cities (11 provinces) between January 2003 and April 2005. This data set contained information on weekly concession sales, box office revenue, and attendance including tickets sold through 5 different selling channels. They also collected information on different markets and local theater characteristics that may relate to concession revenues (population, unemployment, advertising, etc.). Their data shows a strong correlation between theater attendance and concession sales. I would say that is pretty logical. They also associated concession sales with three broad categories of factors:

  1. Channels of Ticket Distribution - For this they divided ticket sales into two categories: tickets sold at the box office and tickets not sold at the box office (further divided into subcategories). They found that people that don’t buy their tickets at the box office spend more on concessions, specifically those people that buy their tickets at home on the Internet or at kiosks.
  2. Audience Composition -  For this category the authors looked at the number of tickets per transaction. Basically, group size. According to their results, if you go to the theater as part of a large group you’ll probably buy more concessions than if you are in a small group. This relationship stands even considering that people in groups tend to share their concessions. 
  3. Theater Characteristics - Large theaters, measured by number of screens and seats per screen, tend to sell more concessions than small theaters even after controlling for attendance. They also found that theaters located in highly populated cities collect less revenue from concessions. Theaters located in cities with higher unemployment rates have lower concession sales, and theaters located in cities with a larger number of commercial activities per person have higher concession sales. Put together, it may actually be local characteristics that are the more important determinant of concession revenues.

Gil and Hartmann also published a study in Marketing Science in 2009 looking at metering price discrimination, a second-degree price discrimination scheme. Basically, “aftermarket goods” (i.e., the concessions) are set well above cost and the customer’s intensity of demand for these goods provides a meter of how much they are willing to pay for primary goods (i.e., the ticket or admission price). The authors created a model (they call it simple, I call it a headache-inducing mathmare) and fed in some available data on concession sales, box office revenues, and theater attendance (again from Spanish theaters). Their results confirmed the presence of the demand conditions for metering with high priced concessions extracting more money from people willing to pay for the admission ticket. Although, they are not sure if theaters are consciously trying to discriminate across customers with their concession pricing strategies. I’m gonna call it getting as much money possible from people willing to pay it.

I've divided this journey to the movies into three parts. If you've made it this far you’ll know why. At this point I’ll leave you with the argument for a new, more current study. A study (likely multiple studies) that take into account the impacts of the most recent recession on prices, the rise of theaters such as the Alamo Drafthouse (which serve dinner and cater to cinephiles), the influence of independent theaters, the increasingly health conscious consumer, and the rise of digital technology (and the associated surcharges), among other things.

 See you soon so that we may choose what to purchase at the concession stand and then we'll make our way to our seats for the movie.

ResearchBlogging.orgSherwin Rosen and Andrew M. Rosenfield (1997). Ticket Pricing The Journal of Law and Economics, 40, 351-376

ResearchBlogging.orgBarak Y. Orbach and Liran Einav (2001). Uniform prices for differentiated goods: The case of the movie-theater industry Harvard Law & Economics Center, Olin Discussion Paper 337 (Harvard University, Cambridge, MA) DOI: 10.2139/ssrn.290813

ResearchBlogging.orgBarak Y. Orbach and Liran Einav (2007). Uniform prices for differentiated goods: The case of the movie-theater industry International Review of Law and Economics, 27, 129-153 DOI: 10.1016/j.irle.2007.06.002

ResearchBlogging.orgJehoshua Eliashberg, Anita Elberse, and Mark A.A.M. Leenders (2006). The Motion Picture Industry: Critical Issues in Practice, Current Research,and New Research Directions Marketing Science, 25 (6), 638-661 DOI: 10.1287/mksc.1050.0177

ResearchBlogging.orgPascal Courty (2011). Unpriced quality Economics Letters, 111 (1), 13-15 DOI: 10.1016/j.econlet.2010.12.009

ResearchBlogging.orgJohn R. Lott and Russell D. Roberts (1991). A Guide to the Pitfalls of Identifying Price Discrimination Economic Inquiry, 24, 14-23 DOI: 10.1111/j.1465-7295.1991.tb01249.x

ResearchBlogging.orgRicard Gil and Wesley R. Hartmann (2007). The Role and Determinants of Concession Sales in Movie Theaters: Evidence from the Spanish Exhibition Industry Rev Ind Organ, 30, 325-347 DOI: 10.1007/s11151-007-9139-7

ResearchBlogging.orgRicard Gil andWesley R. Hartmann (2009). Empirical Analysis of Metering Price Discrimination: Evidence from Concession Sales at Movie Theaters Marketing Science, 28 (6), 1046-1062 DOI: 10.1287/mksc.1090.0494

Ticket pricing info via ScreenCrush

(image via GeekTyrant)

Wednesday, October 16, 2013

Space Missions: Then, Now, and Future

A new way to follow my blog (in case there weren't enough already): Follow my blog with Bloglovin

To build on yesterday's on "The Integrated Space Plan," here are a couple of neat infographics about space travel. The first is the where-we've-been-where-we-are type that nicely lays out some of the history of space travel. The second details some future NASA missions (dates not taking into account any and all government shut-downs).

Space Travel-revised2

Courtesy of: experiences

Infographic via ScienceDump

Tuesday, October 15, 2013

The Integrated Space Plan

Sean Ragan of MAKE magazine posted this really cool graphic. It was created in the 1980's by analysts at Rockwell International and was called the “Integrated Space Plan.” Ragan had seen the poster in the late 90's and finally tracked it down last year. He was able to was able to connect with a generous donor willing to entrust an original copy of the poster to him long enough to have it scanned at high resolution.

So what is it? Essentially, it is a really really detailed flow chart for establishing a permanent human presence in space.

This is a small, pretty hard to see version. For a serious close-up, I recommend getting the PDF version (linked below) and taking some time to scroll around. At first glance it looks like your monitor has effed up with all the lines. But upon closer inspection you will notice that is organized chronologically from top to bottom, the arrowed lines denote “Evolutionary, Supporting, or Synergistic Relationships” and “Communication/Data Links,” and big circles are “Plateaus of Human Technological Achievement.” The nodes include goals like “Interstellar Traversing World Ships” and “Create New Moons for Mars If Required.”

Put simply, this is amazing!

Integrated Space Plan (.PDF)
Integrated Space Plan (.PNG)

Note: Should you decide to go with the PNG image, know that it is not large in terms of data, but in terms of pixels, it is huge: 16800 x 27000. That means that your browser may not be able to display the image. If this happens, try  right-clicking on the link, selecting “Save as…”, and then opening it in a dedicated image-viewing and/or editing program.

Story Links:

Make's "The Rockwell International Integrated Space Plan"
Grist: "Exposed: Manufacturing conglomerate’s plan for moving humans off of Earth"

Monday, October 14, 2013

Socialite in the Dark: Do Eyes Really Matter When It Comes To Schooling?

It has been a while since I've visited the topic of blind fish. I know, I know! What took me so long, right? Well, I was browsing for fish papers, ‘cause I take care of lab fish now (I’m working my way up to Fish Whisperer status), and I came across a paper in Current Biology about the schooling behavior of cavefish, specifically the effects of eyesight loss on this behavior.

There are two main types of social “collective behavior” in fish: shoaling and schooling. Shoals are defined exclusively by social attraction, simply being near each other in a group. To form a school, individuals must also maintain coordinated body position with their schoolmates, showing polarized orientation and synchronized movement.

In a 2011 post, The Sleep of the Blind Fish, I introduced you to Astyanax mexicanus, commonly known as the Mexican cavefish or Mexican tetra. I’ll let you visit that post for more details on this species, but for today know that it has two, interfertile forms: the normal or surface form is pigmented, sighted, and has a natural photoperiod, and the blind form is albino, has no eyes, and lives in dark caves. The normal form actively groups into schools and shoals while the cave form has reduced this behavior. A study by Johanna Kowalko et al. looked to quantify this schooling behavior. To do this they made a sort of fish mobile attached to a motor. As the grouped plastic model fish on the mobile moved, the live fish had the option to join, orient with, and follow the group or not. Images and videos allowed the researchers to measure the position of the fish, average and proportion of time each fish spent with the school, and nearest neighbor distances. They found that surface fish followed the model school while cavefish did not. The surface fish swam significantly closer together than did the cavefish. Also, the cavefish showed a loss of the tendency to swim oriented to one another, or school, as well as a decreased tendency to shoal.

Greenwood et al. (2013) Fig. 1
Okay, so why is this? What do you need to do (or have) to form a group? Some type of sense, right? I mean, you need to find others of your species, be able to sense your place in the group, and be able to respond to others in your group. As we know, the cavefish have adapted to a dark environment and so have no eyes. However, they do have a increased number and distribution of taste buds and cranial superficial neuromasts (mechanoreceptors that detect movements and pressure changes in surrounding water, think lateral line or “touch”). Kowalko’s group found that surface fish have significantly fewer and smaller cranial neuromasts than do cavefish, likely an adaptation to cave life. However, they did not find this adaptation to have a large effect on the evolutionary loss of schooling. I’ll bet that your brain is jumping to the next logical conclusion: vision is important. And you would be correct. The researchers did a series of tests where they tested both types of fish in various light conditions. The surface fish actually preferred the dark, but when they were in the dark they swam farther apart and lost schooling behavior while the cavefish were unaffected by the lighting conditions.

Let’s take the next step: Is this a learned behavior or is it dependent on having eyes? It is known that cavefish develop eyes, which undergo apoptosis and degenerate. So if a surface fish were to lose its vision early in development, would it then behave like a cavefish? To test this, the researchers removed one, two, or no lenses/eyes in surface fish larvae (with some awesome microdissection skills I’m sure!), allowed them to grow up, and then tested their schooling behavior. They found that the removal of both lenses caused the fish to swim farther apart than partially-sighted (one lens) or control fish. The partially-sighted fish could follow the model school but still shoaled farther apart than did full-sighted controls.

Next, Kowalko's group wanted to see what was going on in the brain. Recent research has shown that surface and cavefish have different levels of monoamine neurotransmitters (signaling chemicals in the nervous system).  They used inhibitors to alter serotonin and monoamines. Then they ran their schooling tests. They found that serotonin levels make no difference, but preventing the breakdown of monoamines decreases schooling behavior and results in significantly greater distances between fish in the shoaling tests. These results are consistent with other evidence that a molecule involved in the synthesis of dopamine (a monoamine) affects schooling behavior in cavefish.

Finally (whew!), they performed quantitative trait locus (QTL) analysis. Basically, this is a statistical method that links the phenotype (trait) measurements and the genotype (molecular markers) to explain a genetic basis for a complex trait. They found homozygous cave alleles at a marker underlying linkage group 27 that results in a decrease in schooling behavior and a dark preference. They also found schooling QTL that does not fall in the same place as the QTL for dark preference, eye size, pupil size, or neuromast number. This means that there is are both vision-dependent and vision-independent genetic contributions to the evolution of schooling behavior. Interesting.

Is there a story here? Well, sure. Perhaps when the sighted, cavefish ancestors arrived in their new, dark homes they couldn't school because of the lack of light. Their new cave environment also had a different ecology than their surface habitat. For one, it had a lack of big predators. Schooling equals protection in numbers, so a lack of the need of protection equals a lack in the need to school. For another, caves have scarcer food. Groups eat more and eat together. When there is less food and it is more spread out it is advantageous to find and eat it alone. Put together, this relaxed the selective pressure on schooling behavior causing multiple genetic changes, only some of which are vision-dependent.

ResearchBlogging.orgJohanna E. Kowalko, Nicolas Rohner, Santiago B. Rompani, Brant K. Peterson, Tess A. Linden, Masato Yoshizawa, Emily H. Kay, Jesse Weber, Hopi E. Hoekstra, William R. Jeffery, Richard Borowsky, & Clifford J. Tabin (2013). Loss of Schooling Behavior in Cavefish through Sight-Dependent and Sight-Independent Mechanisms Current Biology, 23, 1874-1883 DOI: 10.1016/j.cub.2013.07.056

See also:

ResearchBlogging.orgAlison M. Bell (2013). Evolution: Skipping School Current Biology, 23 (19) DOI: 10.1016/j.cub.2013.08.022

ResearchBlogging.orgAnna K. Greenwood, Abigail R. Wark, Kohta Yoshida, & Catherine L. Peichel (2013). Genetic and Neural Modularity Underlie the Evolution of Schooling Behavior in Threespine Sticklebacks Current Biology, 23 (19), 1884-1888 DOI: 10.1016/j.cub.2013.07.058

(images via Seriously Fish)

Friday, October 11, 2013

The Ultimate Mentor Adventure!

Marvel Comics is looking for the next Jane Foster! The character in Thor and its sequel Thor: The Dark World is an astrophysicist played by Natalie Portman. Natalie, who graduated with honors before attending Harvard University, enjoyed playing a scientist and believes in encouraging girls in these types of roles. As such, she is working with The Walt Disney Company (who owns Marvel Entertainment as of 2009) in a new endeavor called the Ultimate Mentor Adventure.

Natalie and the Ultimate Mentor Adventure aim to "empower girls ages 14 and up in grades 9-12 to embark on a journey that will allow them to explore their potential in the world of STEM: Science, Technology, Engineering and Mathematics. Through the collaborative efforts of Marvel, the National Academy of Sciences, and Underwriters Laboratories, Inc., girls will have a chance to go out into the real world and ask successful women in STEM fields about what they do, how they got where they are…and how others can follow in their footsteps."

The finalists will get the opportunity to some of these incredible women in science, conduct interviews, participate in experiments and interactive events, go behind the scenes, and attend the premiere of Marvel’s Thor: The Dark World on opening day! To enter you must download, complete, and submit some forms (by October 20, 2013, 11:59 p.m. Pacific Time). Then you must interview a successful woman working in a STEM field in your hometown. Finally, you create a 5-minute video about yourself, uploading it to the Ultimate Mentor Adventure website.

Kinda wishing I was 14 again.

In case you didn't get that URL, here it is again:

Monday, October 7, 2013

Bohemian Gravity!

Warning, there is a lot of awesome in this video.

Wednesday, October 2, 2013

The Festival of Bad Ad Hoc Hypotheses

Do you live in or near Cambridge, Massachusetts? Did you know that there is a Festival of Bad Ad Hoc Hypotheses (BAH!) over at MIT?

"The Festival of Bad Ad Hoc Hypotheses (BAH!) is a celebration of well-argued and thoroughly researched but completely incorrect evolutionary theory. It is put on by Zach Weinersmith (cartoonist of SMBC), breadpig (publishers of SMBC and XKCD), and MIT's Lecture Series Committee. It is sponsored by the EvoS Consortium and This View of Life magazine (Editor-in-Chief David Sloan Wilson)," and it is part of the Cambridge Science Festival. Ben Lillie, director of Story Collider, will be the emcee for the evening (and I am hoping that he will record it for his podcast!).

The event was initially inspired by this comic:

BAH! will be held in MIT's Kresge Auditorium (48 Massachusetts Ave., Cambridge MA, USA) on the evening of October 6th, 2013. Doors will open at 6:15 PM and the event will start at 7 PM. There will be 7 speakers presenting their bad theories in front of a live audience and a panel of geeky judges. These judges will determine who presented the best theory who will together determine who presented the best theory according to the following criteria:

  1. Force of Science - how much “scientific” information was brought to bear (graphs, real citations, “research” etc.)
  2. Artistry - how unexpected and clever the idea and presentation are, and how well the presentation is delivered.
  3. Parsimony - the simplest theory that explains the most data is best.
  4. Strength of Defense - how well did you defend your views to the judges. 
    • Note - being funny is not a good defense.

Unfortunately, submissions for this BAHFest closed on March 10th. But they might do another one in the near future, so keep thinking up bad hypotheses and maybe you can present.

Tickets for this event are $5 for students (valid student ID needed) and $10 for non-students.

Visit the BAH! website for tickets and more information. Oh, and if you go, leave a comment to tell us all about it!

Tuesday, October 1, 2013

Mars Explorer Barbie

Barbie® Doll is an iconic toy, and sure, she's gotten quite a lot of flak in recent years over her body size issues and bubbleheadedness. But Mattel, now the largest toy company in the world, has been taking some steps to revamp Barbie's image. Am I saying that there aren't still primped, empty-headed ones out there? No, there are still plenty of those. I mean, all University Barbie dolls are cheerleaders? Really?

But, on the positive image side, Barbie is also a computer engineer, a paleontologist, an architect, a pediatrician, a veterinarian, and even ran for President in 2012. Now meet Mars Explorer Barbie. Mattel released this new doll on Monday (Aug. 5, 2013), as part of their "I Can Be..." series, to coincide with the first anniversary of NASA's Curiosity rover landing on Mars. She's got a spacesuit, helmet, space boots, air tank, and is packaged with a cardboard cutout of the six-wheeled Mars Science Laboratory. All decked out in pink, of course. And while this isn't Barbie's first trip to space (there were Astronaut Barbies in 1965, 1985, and 1994 and a Space Camp Barbie in 1998), this is the first to be produced in partnership with NASA.


CinemaBlend's "New Mars Explorer Barbie is Stylish"'s "Mattel's Astronaut Barbie Becomes a Mars Explorer with NASA Help"
CollectSpace's "Mattel's Astronaut Barbie becomes a Mars Explorer with help from NASA"

Images from's "Barbie in Space: Iconic Doll's Astronaut Looks (Photos)"

Monday, September 30, 2013

Larks vs. Night-Owls: What Your Sleep Patterns Say About You

Ugh, Monday morning really kicked my butt. Even my strong coffee failed to wake me up completely. Of course, I drag-ass most mornings, being almost useless before 10 a.m. On the flip side, I have always been wonderfully alert and productive after 7 p.m. A night owl I am, and this seems like a good topic for discussion. What determines your circadian rhythms and what does that mean for your personality?

A circadian rhythm is an endogenous, near 24 hour cycle in the process of living organisms (plants, animals, fungi, cyanobacteria). They have clear patterns and are important in determining physiological processes and activities. They are adjusted to the local environmental cues, like the light-dark cycle. I point this one out specifically because we are looking at the sleep-wake rhythm. Now, as with all things, there are individual variations, and a diurnal preference (or “morningness-eveningness (M-E) dimension” or nocturnality) is one of them. Your preference categorizes you into one of two chronotypes: (1) a lark or early riser who goes to sleep early in the evening and wakes up early in the morning or (2) a night owl who goes to sleep late in the evening and wakes up late in the morning.

Did you know that this preference is actually genetically controlled? Yeah. A paper published in Science in 2007 by Godinho et al. used N-ethyl-N-nitrosourea (ENU) mutagenized mice and screened alterations in circadian wheel-running activity. These screenings revealed a group of animals with a longer than average circadian period. They named the mutant gene “after hours” (Afh) and mapped the dominant phenotype. Then they selected those mice displaying the most extreme circadian phenotype for a genome scan. This scan revealed that the Afh mutation results in the substitution of serine for Cys358 (C358S) in Fbxl3, an F-box protein with leucine-rich repeats. Basically, Afh is a variant of the Fbxl3 gene, one of a large gene family that controls the breakdown of specific proteins in the body’s cells. After the identification of this variant, the researchers looked at the circadian expression profiles using in situ hybridization, immunohistochemistry, and Western blotting. They found that Afh affected steady-state levels of the principal negative-feedback regulators of the clock (Period genes Per1 and Per2, Cryptochrome gene Cry1, and the positive regulator Bmal1). One of the key components was the Cry1 gene which delayed the Cry protein breakdown, slowing the molecular feedback loops and lengthening the circadian cycle.

Now that we have our genotype (and resulting sleep-wake phenotype) explanation, let’s move on to personality traits. There is a rather expansive amount of literature showing that larks exhibit optimal cognitive function earlier in the day and night owls later in the day (hmmm…maybe I can coin the term “morning drag-ass syndrome”? MDAS? Pronounce that Midas because it’s gold!) A paper published in 1999 by Roberts and Kyllonen examined these cognitive differences, notabally intelligence, in a study of 420 participants. The participants were United States Air Force recruits undergoing their six week basic training and, as such, had known, homogeneous sleep-wake cycles, dietary intake and social constraints. These recruits completed two self-report measures of circadian type (Morningness-Eveningness Questionnaire and Composite Circadian Scale), a standardized intelligence test (Armed Services Vocational Aptitude Battery or ASVAB), and a standardized memory and processing test (Cognitive Abilities Measurement Battery or CAM-IV). The results of this study showed that night owls scored higher in measures of memory, processing speed, and general intelligence. I almost feel like I need to insert an immature, raspberry-accompanied I’m-smarter-than-you dance in here. Almost.

Admittedly, this final topic was the genesis for this post. I came across a newly published paper about the “Dark Triad” and just had to stop and read it. I mean, Dark Triad? Sounds like something Harry Potter might battle. Basically, the Dark Triad is a psychological term that describes a set of traits that include the tendency to seek admiration and special treatment (narcissism), to be callous and insensitive (psychopathy), and to manipulate others (Machiavellianism). Lovely. Granted, there are other determinations (google The Dirty Dozen Scale….awesome name!), but summing them all up gives you a picture of a person who is basically a giant toolbag. And there is some evidence suggesting there may be a genetic correlation to these traits. This new paper by Jonason, Jones, and Lyons looks at how the Dark Triad may be associated with the night owl chronotype. They had at 263 participants take online assessments that measured the three traits as well as the Morningness-Eveningness Questionnaire. The results of this study showed a correlation between being a night owl and the Dark Triad. The authors do a pretty good job at attempting to explain why this is so, hypothesizing that these Dark Triad traits may be evolutionarily important. They posit that these traits may give some type of night-time specialization, facilitate a cheater strategy, and enable a protean social style. They did not find any sex differences which eliminates sexual selection from their argument. This is sad because they were only able to use male “night-time adventures” once in their explanation. An overall interesting study that both allowed me to say Dark Triad a lot while removing all want to immaturely dance around.

If you have stayed with me this long then I commend you! In my defense, you did get three papers instead of the usual one. But anyway, what are we to take from all of this? That because I’m a night owl I am also an intelligent jerk, and that I can’t help it because it’s all genetic? Oh dear, I hope not. While I like to think I am intelligent, I hope that I am not a narcissistic ass-hat. So, what I guess that I’m saying is take of this what you will, and maybe read more studies.

ResearchBlogging.orgSofia I. H. Godinho, et al. (2007). The After-Hours Mutant Reveals a Role for Fbxl3 in Determining Mammalian Circadian Period Science, 316 (5826), 897-900 DOI: 10.1126/science.1141138

ResearchBlogging.orgRichard D. Roberts, & Patrick C. Kyllonen (1999). Morningness±eveningness and intelligence: early to bed, early to rise will likely make you anything but wise! Personality and Individual Di€fferences, 27, 1123-1133 DOI: 10.1016/S0191-8869(99)00054-9

ResearchBlogging.orgPeter K. Jonason, Amy Jones, & Minna Lyons (2013). Creatures of the night: Chronotypes and the Dark Triad traits Personality and Individual Di€fferences, 55, 538-541 DOI: 10.1016/j.paid.2013.05.001

(image via the Sleepio blog)
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