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The Case for Casual Biometrics

December 20, 2012 Article Start Page 1 of 4 Next

Lecturer and developer Stefano Gualeni explains how his team employed biometric testing -- once the purview of big publishers and chiefly used to test action games -- to improve player response to a casual, indie iOS game.

"For the most part, the English and American whale draughtsmen seem entirely content with presenting the mechanical outline of things, such as the vacant profile of the whale; which, so far as picturesqueness of effect is concerned, is about tantamount to sketching the profile of a pyramid."

Herman Melville, Moby Dick; or, The Whale, Chapter LVI - Of the Less Erroneous Pictures of Whales, and the True Pictures of Whaling Scenes.

This article charts the history of a whale. Or rather, it is the story of my whale: the iPad video game titled Gua-Le-Ni; or, The Horrendous Parade.

I designed and developed Gua-Le-Ni between 2011 and 2012 with Italian development studio Double Jungle S.a.S. of Padova, Italy, and I call it "my whale" because one of the main tropes of such game, namely the fascination with mythological creatures, captured my curiosity since my early childhood.

I still remember my mother going through books with etchings of fantastic animals with me, and perhaps it is going through these early memories that the conception for a game involving fantastic beasts was first formed. I am sure it was a similar fascination that drove my decision to become an architect in the first place.

Toy cubes with animal parts printed on their faces constitute the main player-interface for Gua-Le-Ni.

This article tells the story of how my obsessions as an individual, as well as my inclinations as an independent game designer, became entangled with academic research. Specifically, it is about Gua-Le-Ni, and about how the development of the game was influenced by scientific experiments.

To begin with, the production of my game was slowed down and structured in a specific modular to accommodate the needs of the research team at NHTV Breda University of Applied Sciences. The coordinated effort of the Italian development team and the Dutch research team made Gua-Le-Ni the benchmark to assess the possibility to integrate psychophysiological (or biometric) experiments in the quick iterative production cycle of casual and independent game development.

Whereas on a personal level, Gua-Le-Ni is a work of love, a way to embrace my childhood experiences and to explore my understanding of the creative process, for the research team working on my game, it was an object of dispassionate observation reduced to its mechanical and quantifiable workings. Analogous to Melville's pyramid in the quote from Moby Dick, both perspectives are sketches of the same whale -- my whale.

From the point of view of a player, Gua-Le-Ni is an action-puzzle video game that takes place on the wooden desk of an old, befuddled British taxonomist. On his desk lies a fantastic book: a bestiary populated by impossible, finely drawn animals. Just like the monsters of myths and folklore, the impossible creatures in my game are combinations of parts of real animals. To understand what I mean, it might help to think of legendary creatures like the sphinx, the Minotaur, or South Park's Manbearpig.

Feeding the beasts in Gua-Le-Ni does not only temporarily stop their relentless stampeding, but can also modify the beasts' composition or increase their value in terms of points awarded upon their correct cataloguing.

My paper abominations walk across the illustrations of the old bestiary. Above, you can see a CA-BIT-DOR-STER: a four-module beast with the head of a camel, one body part of a rabbit, another of a condor, concluded with a lobster's tail. The main goal of Gua-Le-Ni is to recognize the components of the fantastic creatures and their relative order before one of them manages to flee from the page (which is the Game Over condition).

Mentored by the old taxonomist, the player pursues this purpose by rotating, moving and spinning toy cubes with pictures of animal parts printed on the six faces of the cubes. A paper beast is correctly recognized, and thus prevented from escaping the bestiary, when the player manages to match the illustrations on the top faces of the taxonomic cubes with the paper beast currently in play.

Departing from a player's perspective and taking yet another point of view, namely the academic framework that underlies my doctoral studies, Gua-Le-Ni is a creative artefact that complements my dissertation. It exemplifies the potential of video games for the explanation, the testing and the development of philosophical concepts and questions. In the specific case of my game, the playable philosophical notion is David Hume's understanding of the imaginative capabilities of the human mind. Luckily for you, neither this aspect of the game nor my sickeningly personal design process will be discussed here.

For the sake of the audience of Gamasutra, instead, this article will focus on one aspect of my whale, namely an aspect which has a practical dimension for people developing video games in short production cycles. More specifically, I will present some of the opportunities offered by biometric testing methods for the development of casual video games (the development of which are characterized by quick iterations).

The practical use of biometry in Gua-Le-Ni will be presented as a case study that clearly demonstrates the advantages offered by biometric testing. The benefits and the viability of a biometric approach for the developers of casual games are extensively discussed in the academic papers that discussed our methods and experiments (see references) and will be shortly presented to the reader in the conclusion of this article.

Article Start Page 1 of 4 Next

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Stefano Gualeni
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Dear Dario, thank you for your kind comment and your interest. In case you are eager to know more, you can find an academic account of our process on our benchmark game at (it is one of the two papers referenced at the end of the article).

As far as hardware goes, we started with this research project roughly two years ago with one of the cheapest set of biometric sensors on the market called Procompt Infiniti produced by Thought Technology:

We decided to use a very basic setup, clearly, because the original scope of our applied science and our industry partners was that of working towards the possibility of making our framework and methodologies viable for small developers. Right now, the set costs a little less than four thousand dollars, which is not too bad. :)

The biggest problem that our researchers and technicians had to solve, however, was not related to the sensors or to the creation of a neutral and isolated room to test in. The hardest problems they had to tackle consisted in bringing metrics from the game, game play videos and biometric data together in a single timeline, on a single machine where changes in psychophysiology, game performance, muscle contraction and game events could be assessed and compared.

Without a working framework capable of allowing hardware and software to communicate automatically, it is nightmarish to perform biometric analysis on video games. It was the case of Gua-Le-Ni, when our framework was just at the beginning of development. It took the technical part of our research team more than a year to develop a working and reliable version of the framework. I believe it's safe to say that, in our case, expenses and difficulties did not end with purchasing and setting up the biometric sensors.

Hopefully, commercial set of biometric sensor will soon come with a framework which is easy enough to utilize and obtain answers from. I do not know if we will be able to disclose the software we wrote and the hardware solutions we found, but I presume more technical papers will be published by the more technical people in the research team.

Once again, thanks for your interest.

David Serrano
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Stefano, we know playing games will trigger a physiological responses in (most) players. But the physiological response to a game doesn't necessarily correspond to the player's opinion of the game. Or to their gameplay preferences in general, correct? Raising a player's heart rate or muscle tension could mean he or she finds the game exciting, but it also could mean the game is frustrating them or pissing them off. If I was tested while playing a game on the highest difficulty setting, I know my heart rate, blood pressure, breath rate, muscle tension, cortisol levels, etc... would spike sharply. But this wouldn't mean I found the game exciting or that I was enjoying it on any level. Because in reality, I find that playing games on higher difficulty modes sucks every second of fun, pleasure or enjoyment out of the experience. And my positive or negative opinion of games is largely determined by how well I believe the normal mode difficulty curve has been balanced for the average player the audience, and how well the casual curve was balanced for new or low experience players. So when biometric data is collected, is combining it with, or reconciling it against the player's verbal or written feedback part of the process?

Stefano Gualeni
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Dear David, thank you for the very interesting question and for having shed light on the fact that I have - perhaps - not been thorough enough in the article with regard to our (multi-leyered) process. As you might imagine, writing this article for a non-specific public demanded decisions about what to omit or simplify about the ways in which we gathered, collated and interpreted data.

Your answer could be, very synthetically, found in this sentence of page 2: “To complement a wider quality assurance campaign based on questionnaires, interviews, blind-testing and hard-core performance tests, the Dutch research team at NHTV Breda University of Applied Sciences ran an initial series of biometric tests on Gua-Le-Ni. The aim of these initial tests was to structure a testing methodology incorporating the added perspective of biometry.”

I am thankful for your question because it allows me to elaborate a little more on our work.

So, David, the first thing that you need to keep in mind while reading about our tests is that each subject that tested our game was also exposed to other TWO video games in the same sector and genre of Gua-Le-Ni (casual time-base action video games). In that way we could obtain biometric data about our competitors and have a rough base to compare our game against. However, we did not tell the test subjects that one of the games was developed internally.

On top of that, we administered to every participants mini in-game questionnaires to be filled in quickly between games (normally administered upon ‘game overs’ and to be rapidly filled-in). At the end of each game session with one of the three tested games (ours plus the two control ones), a more thorough questionnaire about the general game experience – also known as a GEQ – was filled in by our guinea pigs.

At the end of the process described above, we would informally discuss with each participants the merits of the games, making notes about the difficulties, the feelings, the interfaces and generally anything they wanted to disclose about their experiences. The interviews mostly focused on Gua-Le-Ni, which (depending on the subject) was either the first, the second or the third game of the series of action-based casual games they played.

Interviews were the most useful for me as a designer, but they were also poorly reliable. As it turns out, players tend to have a very selective and distorted set of memories about their game experience. The specific literature informs us that they can remember very well the beginning and the end of the experience, and perhaps register accurately a particular event that happened during gameplay, but the rest of the playing session is usually vague in their cognition and is mostly re-constructed a posteriori. The vagueness and the cognitive blanks could be filled, in our case, with metrics, biometrics and videos. In that way, we can complement their feelings with an objective tracking of the game sessions from both an in-game performance point of view and a bodily one. Besides, interviews and records of the game states are normally crucial in determining how the bodily signals should be interpreted (or at least suggest a way in which they could be read.

The riddle of the smiles during ‘game overs’ that was cited as an example in the article was solved precisely during informal interviews, where the players specified that the end of their games were received positively. During the interviews they specified clearly that they wanted to keep going on with the game and that the gradual disappearance of the beast in play behind the curled page always left them with the feeling of having ‘almost solved it’, hence their smiles.

The positive valence of those stress spikes remained a mystery until we compared our notes about the interviews with the actual stress graphs. Interesting, isn’t it?

David Serrano
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Stefano - Thank you for taking the time to reply. Yes, it's very interesting because during my career in magazine publishing, we went through a similar period where new techniques and systems were implemented with the goal of reducing or eliminating the level of subjectivity and guess work from creative and technical processes. So I see many parallels between the problems you're addressing with biometric data and the problems other industries addressed through a marriage of statistical process control and science. I think the game industry will eventually create similar systems, standards and procedures. But implementing them will be a slow, tedious process with a steep learning curve. But the end results are absolutely worth it.

Susan O'Connor
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Interesting, thanks for this

Stefano Gualeni
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Dear Susan, thank you for having read and commented my article.
In case any of you were interested in knowing more about our ongoing process, our framework for biometric analysis, or simply feel like meeting up, shaking hands and the like, well... You might be interested in knowing that I will be one of the speakers at the upcoming 2013 Games User Research Summit in San Francisco on March the 26th. (

In case you are planning to attend, feel free to contact me. Also, a new game might be on the way...