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a Studiolab production.


food design course at TUDelft
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De meningen ge-uit door medewerkers en studenten van de TU Delft en de commentaren die zijn gegeven reflecteren niet perse de mening(en) van de TU Delft. De TU Delft is dan ook niet verantwoordelijk voor de inhoud van hetgeen op de TU Delft weblogs zichtbaar is. Wel vindt de TU Delft het belangrijk - en ook waarde toevoegend - dat medewerkers en studenten op deze, door de TU Delft gefaciliteerde, omgeving hun mening kunnen geven.

Posts in category fallacies of interaction design

the cube sphere egg fallacy (#5)

My colleague Thomas likes to quote a professor of his as being very happy whenever his students designed an interactive object in the form of a glowing cube, because this meant that the cube had been done and that the real design could start. I guess that it is always a strong temptation, having to do in part with science fiction imagery, such as the Borg cube


the Borg, being an entirely rational race, make cubic spaceships because they are not concerned with aerodynamics. Since these cubes will never enter an atmosphere, they can be cuboid and covered with fiddly little appendages. When they feel like doing something wild, they make a spherical spaceship.

On the other hand, if a human designs a cubic object, particularly if it is supposed to be grabbed by someone, it is a safe bet that he is a taking an easy way out and neglecting thought. Just try to remember how many perfectly cubical objects you know. Not many, right?

  • dice, cubic so that they can fall on each side with the same probability
  • Rubik’s Cube, cubic for gameplay reason
  • the Power Mac Cube, that was not really a cube
  • the Borg cubes (already discussed, and you are not designing for the Borg anyway)
  • the Weighted Companion Cube in the videogame Portal, designed to weird you out with its cubic yet loving inexpressiveness
  • silly MP3 players from 2 years ago
  • frankly stupid cube shaped clocks that go out of their way to make reading the time difficult

…one runs out of presentable examples pretty fast. And that is because a cube is not such a good form to hold in your hand: first of all it is pointy, and secondly it makes sense only if all its faces are equally significant and work well by being exactly the same size. It is not strange that there are very few cubes around us, while there are millions of objects that are bricks, tablets, slabs, and thin plates: their asimmetry has a reason, while the cube’s peculiar and extreme simmetry is just … a form. Real world objects have a good end and a bad end, a business end and a handle end, a top and a bottom, a front and a back. Their sides specialize, to a degree, just like animals – notice that most higher animals are symmetric only on one plane.

Cubes, on the other hand, have no favorite resting position. Each side is equally good. 




These are MP3 players and sharing devices, whose designer I will not mention, and they are really wrong. They offer no use cues: are you supposed to shake them, squeeze them, press them or put them one close to the other? Or eat them with a fine Chianti? Why do they glow, other than they can be made to glow? The bland cube, in its simmetry, is rivaled only by the blander sphere (or egg). 


These (horribly boring by now) glowing LED spheres make some sort of sense, because they are hand sized, meant to be grabbed and I bet that you have to squeeze them to switch them on and off. And this is about the only meaningful interaction you can have with a featureless sphere, other than throwing it at people and small animals. The moment you want to add more interactions, though, you will suddenly realize that the sphere is the wrong shape.

The sphere’s best buddy is the egg. Nicely aerodynamic and archetipal, it is a very good shape for containing a baby chicken and making kitchen timers. Oh, and chocolate eggs. And debatable USB minipicture frames distributed by Brando. Here on the side you can see probably the ugliest MP3 player in the universe, that combines the senseless egg shape with commands on the headphone wire (bad) and an incredible fake marble skin. That’s what I call a clear winner, and a good point to stop rambling.



If you liked this post, you might also like the previous fallacy.



the magic fallacy (#4)

In the vein of the abstract fallacy, today I point out the magic fallacy. The most typical case is when a project is described in terms similar to these:

the user opens the box, a green light inside it starts pulsating and the user feels a magical feeling

How exactly does this happen? Of course the user does not know why e.g. opening a box and seeing something gives him a magical feeling, but the designer should know. To put it more formally, a designer is not allowed to suppose psychological changes in the user without indicating the psychological means that produce these changes. Of course it is possible to surprise users, to delight them and even to make them feel like magic, but how do you do that? The project description should indicate what psychological mechanism happens. Is it a visual reference to something well-known? Is it a perceptual trick? Is it culture specific?

If you state that Canon’s installation at Salone del Mobile, the enormous NEOREAL piece installed in Triennale, creates a magic feeling through large scale complex geometries in a dimmed room


and the illusion of being in an underwater world where you can interact with glowing jellyfishes



then I believe you. There is no theoretical reason, it is just that, in my model of human behavior and reaction, large scale immersive spaces where a touch of sensorial deprivation is combined with big, sharp biological images in soothing blue DO indeed produce a magical, far-out, slightly hallucinatory feeling. Just like a desser composed of a kiwi, a tangerine and some peanuts produces a vaguely unsatisfying bizarre feeling at the end of lunch. 


To fall back on the well known, let ne quote the usual Proust: we are not just told "I ate a little sweet dipped in tea, and I felt incredibly happy." The narrator lets us know exactly what connects the happiness to the food (and also the process by which he finds out the connection). His question

D’où avait pu me venir cette puissante joie? Je sentais q’elle était
liée au goût du thé et du gâteau, mais qu’elle le dépassait infiniment,
ne devait pas être de même nature. D’où venait-elle? Que
signifiait-elle? Où l’appréhender?

in the English translation by C. K. Scott Moncrieff:

Whence could it have come to me, this all-powerful joy? I was conscious
that it was connected with the taste of tea and cake, but that it
infinitely transcended those savours, could not, indeed, be of the same
nature as theirs. Whence did it come? What did it signify? How could I
seize upon and define it?

should also be the designer’s question. I do not deny that a green light pulsating in a box can be a source of magical feelings, but whence the connection? What does this feeling mean? How can we grab it and define it?

(the Canon NEOREAL photographs are taken from the project site: the kiwi picture is unfortunately mine)



the abstract fallacy (#3)

Whenever students tell me …and this phenomenon will be visualized by abstract graphics… or basically anything that includes the word abstract, I know that there is trouble on the horizon. Why? Well, this is abstract


The Matrix screenshot



this is abstract


and this too!


this, btw, is a variation on the Sierpinski triangle fractal, made by a guy that calls himself FireLizzard with a fantastically interesting piece of software: Context Free.

But to go back to why saying abstract is bad, I should be more specific: it is bad only when you say it to create a smokescreen over missing visuals or even serious difficulties in information visualization or interaction design. Abstract graphics, particularly if they are meant to convey some information (as opposed to being screensavers or cute wallpapers) are damn hard, I daresay because they sit at the intersection of graphic design and information design, with the extra difficulty that they cannot contain representations of real world objects or icons that refer to them (abstract, you see…), so if you want to represent the state of health of an old person (for example) you can’t just have an old-guy icon bent double because of backache or happily strolling around. You have to come up with something else, and I bet that it is going to be pulsating and glowing like a damn Macintosh power LED. But I digress.

To sum it up,  abstract is OK as long as you realize that it is a placeholder, and that making those abstract graphics work well could easily be the most difficult part of the whole design.



in other news: Max Bruinsma is a highly articulate guy with very interesting things to say on design

the Hip Hop fallacy (#2)

it can be summarized as the following statement: everybody wants to make music: I will give them the means to. This fallacy leads to a host of unfortunate, if occasionally amusing, design projects featuring benches, walls, stools, buttons and buttonoids, bus stops, bicycles and teddy bears that emit sounds when people variously interact with them.

Hip Hop fallacy projects tend to be illustrated by videos with happy youngsters dancing, if at all possible wearing very broad pants or very tight pants or no pants at all, depending on the current fashion. The videos last three minutes, which is also about the duration of time such a design stays interesting. No regard is ever paid to the fate of the bystanders: you know, the other people that are waiting for the bus, or want to use the park… and maybe do not like your music. Or sounds.

YouTube Preview Image

As you listen to the above classic piece, please consider the following four commonly available facts (no users have been harmed in the process of making them available: I just opened my eyes):

(1) right now, everybody in the Western world has the means to make music or can obtain them for a sum in the ten Euro range. There are online musical instruments, every computer is powerful enough to make music, you can buy supercheap Chinese-made keyboards and guitars. If you are into percussions, there is even a fine tradition of making your own instruments. It is not a problem of availability. It hasn’t been for quite a while – if you have the time, look into the origins of American black music.

(2) Despite this fantastic availability of means, most music we listen to is made by -let’s face it- professional musicians. Much as I would love it to go out of the IO Building in TUDelft, and just stumble upon improvised orchestras, ad-hoc marching bands and even occasional choirs, this just does not happen. Most people do not want to make music. Or maybe they want, but in the same vague sense in which I want to visit Bejing sooner or later, but I have not made any actual plan to do so. This situation was different in the Buddenbrook-era past, when live music was the only music, and every offspring of a good bourgeois family was simply required to be able to play and if possible sing.

(3) third,  making music is difficult, as anybody can easily find out when sitting down for the first time at a piano keyboard. You press a key and a sound comes out: you press many keys, together and in sequence, and crap comes out. Don’t even think about instruments like bagpipes, violins or trumpets, where to even make a sound come out you need significant training. But I know what you are thinking right now: I will use samples!And the results will suck just as bad. Even assembling samples, as any competent rapper or contemporary musician will tell you, requires skills. Just try. As an example, look at these people:

YouTube Preview Image

highly trained musicians, very difficult montage. Genius director, who is also a bastard because he makes it look so good and so damn easy

(4) Fourth commonly available fact, easily discoverable through summary You Tube exploration: most amateur musicians or makers-of-music suck. They have a tiny repertoire, and their technique is not so good. Which is not bad in itself: it becomes a problem only when you give these amateurs the possibility (technical and social) to inflict their not-so-good playing on the innocent. 

At the same time, there is a large population (all the people who bought Guitar Hero) that likes to pretend they are making music, just like other like to pretend that they are space marines. But one should not confuse the desire to pretend with the desire to be.

Recover from this revelation by watching Rapper’s Delight.

the Spaceballs fallacy (#1)

a common disease of interactive projects, particularly of the interactive environments and service design class. Consists of assuming that every surface can, magically, display images and be sensitive to user behavior. Named after Spaceballs, an 1987 Mel Brooks science fiction comedy movie that spoofs Star Wars.

Here an apparently neutral and featureless wall panel



turns out to be a gigantic television screen, complete with an invisible camera for videocalls! Amazing! Imagine what kind of interfaces you could do with that.

If you haven’t watched the movie, go here, at time 5:10 – this also happens later in the movie with other innocent looking  panels in totally inappropriate locations. Also features, albeit in a serious manner, in the opening scenes of Total Recall (1990).


and if you want to claim that my culture consists strictly of SciFi movies from the last millenium, why you are welcome!



first in a series of interaction design fallacies.


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