The job of the special effects designer is to create the perception of reality in the mind of the viewer — to trick the human brain with just a few simple inputs — drops of water, say, falling from a hidden pipe, a few carefully placed lights, an offstage fan. Combine these elements properly and the audience sees a rain storm.

But exactly what kind of rain storm does the show require? Here is where the art of design comes in. For example, in 1998, I used those elements for a production of Shakespeare's Twelfth Night directed by Nicholas Hytner at the Vivian Beaumont Theatre. The show's design aesthetic was infused with a kind of opulence reminiscent of jewel-toned Persian miniatures. One of the major scenic elements, designed by Bob Crowley, was a pool of water. I was asked to create the illusion of a gentle rain falling into this pool. It began with a single drop disturbing the mirrored surface, and then another and another, so that the rain built gradually, almost imperceptibly, and had a soothing effect on the audience.

But in 1982, for Jonathan Reynold's comedy Geniuses (produced by Playwrights Horizons and directed by Jerry Guttierez), the rain-pipe, lights, and fans combined with running, shouting, wet actors (doused offstage with Hudson sprayers), doors rigged to crash open as if in hurricane-force winds, amplified thunder, and well-timed strobes to create a typhoon that left the audience gasping.

That it is possible to make an audience sitting inside a building interpret those few inputs so subtly — gentle rain versus typhoon — is a fluke of the way the human brain is designed. Cognitive researchers have shown that human beings literally create reality through perception, that we must learn, for example, as babies to interpret visual stimuli in three dimensions. For a thorough examination of the science behind this phenomenon, there is probably no better book than Visual Intelligence: How We Construct What We See by cognitive scientist, Donald D. Hoffman, a text that should be required reading for any special effects designer. In it, Hoffman states (page 176):

I don't want to claim only that you construct what you see. I want to claim that, at a minimum, you construct all that you hear, smell, taste, and feel. In short, I want to claim that all your sensations and perceptions are your constructions.

Moreover, because mankind has always lived in a dangerous world, we have developed brains capable of processing and interpreting multiple sensory inputs quickly. We have the ability to combine the sketchiest of facts into vivid, full-fleshed truths in a split second (i.e., rustling in bush + growl = lion = run away!). Luckily for the special effects designer, audiences tend to interpret these sketchy facts in a predictable manner, just so long as what has come before — the play itself, the directing, acting, and other design aspects — have primed them properly by the time the effect comes along.

For this reason, it is essential that the effects designer understands how it is that an effect makes sense in the context of the show. I manage this by asking three simple questions about each effect I design.

First, I begin by asking: Why are we doing this particular effect? From my experience, the why of an effect will always fall into one or more of the following six categories:

  1. to tell the story, complete the picture

  2. to establish location or a change of location

  3. to provide a dynamic sense of movement, often moving atmospherics counter to stage movement

  4. for visual interest while covering transitions, scene changes, costume changes, or other mechanics

  5. to show the passage of time

  6. to evoke emotion

With the why answered, I then ask a second question: What is the reality that I, the effects designer, want the viewer to construct? The why elements inform this choice; as a rule, it should be possible to fulfill at least two of the why elements with any single effect.

For example, imagine I have decided to create a bank of ground fog to swirl counter to a turntable as it moves into a new scenic position. I know that low fog tends to evoke a tingly, eerie feeling in the viewer — it is the stuff of graveyard scenes and mystery. When that fog swirls counter to the movement of the turntable, it adds the sense of not only movement in time, but moving toward danger — symbolically, it looks like one of those satellite photos of a hurricane, a resemblance that raises the anxiety level of the audience. And then, of course, even while the swirling fog emphasizes the movement of the turntable, it has the practical effect of distracting the audience momentarily from the mechanics of the scene change.

With the why and what answered, it is time to consider the last question: How, technically, am I going to achieve the effect? Will I use dry ice or glycol fog? Real fire or silk fire? Paper snow or foam snow?

There are many design considerations that will indicate what an effect should look like; these will ultimately help to determine the how. For example, I need to take into account the stylization of any given production. Is it realistic or conceptual? Is it simple or baroque? To understand this fully requires working closely with the rest of the artistic team, especially the director, set, and lighting designers. For the special effects designer, good collaboration with the other designers is essential. You can design the best rain ever, and if it is not lit properly, no one will see it. But if it is lit with genius, your design will look spectacular.

Determining the how also means that practical considerations must be grappled with early in the design process. Some of these considerations will be found in the script. For example, if you have ballerinas onstage in Scene II, you don't want them slipping around on snow from Scene I.

Other considerations will have little to do with the show itself but are just as important. For example, with theatre productions, design will inevitably be shaped by the availability of real estate. Every theatre has its own personality and peccadilloes. Sometimes fate will hand you an unusually deep or tall space, or one with a hellish air-handling system. Some cities don't allow open flame onstage; others allow only small amounts of propane inside a theatre. Then, budget is inevitably an issue, as are the qualities of the personnel available to build and run the show. That said, limitations in any of these areas are not always liabilities. On the contrary, shoe-string budgets and odd spaces can inspire enormous creativity all around.

This third phase of the question process is also when I begin to think deeply about how I am going to trick the audience into seeing what it is I want them to see. In theatre, the audience's sense of sight is the perceptual channel most often exploited by the special effects designer. This is because vision, for those with all senses intact, is our most important means of perceiving the world, a fact born out by the disproportionate space in our brains taken up by vision-processing. Atmospherics — rain, mist, lightning flashes, fire — are the visual stock in trade of the effects designer. Also in the category of visual effects are tricks such as blood-spurting knives, vanishing actors, and period weapons that flash and smoke when fired.

Keep in mind, though, that the most successful effects will appeal to more than one sensory channel. Visual inputs alone will not convince an audience — they must be combined with sound and even scent and touch when possible to be truly believable. Brilliant flashes of light are meaningless on their own, but coupled with the sounds of rain and thunder, they make a storm.

Indeed, special effects designers have long sought to beef up an effect by stimulating the other senses along with vision. B-movie producers and amusement park designers are notorious for using touch to terrify their audiences. Show rats scurrying about and then blow a tickle of air on the backs of an audience's ankles, and you'll surely elicit screams. In theatre, too, effects that stimulate the audience's skin can be an artful way of breaching the fourth wall, of reaching out from the stage and into the house.

For example, in the current Broadway production of Phantom of the Opera, flame mortars produce radiant heat that can be felt by nearby audience members. In the recent Toronto and London productions of The Lord of the Rings directed by Mathew Warchus, I was asked to find a way to use effects to make the giant Balrog demon puppet more terrifying. This was achieved by using huge fans not only to move the Balrog's wings but also to blast hot air and cinders (actually black confetti) far out into the house just as the curtain rang down on the end of Act I.

The sense of smell is known to be strongly linked to emotion and memory in our brains, which makes it both a potentially powerful tool for a special effects designer and, at the same time, one that is very tricky to use effectively. Scent dispersal systems are widely employed in commerce; they are designed to emit everything from the aromas of freshly baked bread and chocolate to the latest perfumes — indeed, in Las Vegas, each hotel pipes in a signature scent. But in these situations, the aroma doesn't have to appear and disappear on cue, nor does it have to reliably evoke a certain response from those who smell it.

The reality in theatre is different, as I learned when we tried to use scent in The Lord of the Rings. We wanted to enhance three scenes with aromas — fir for Elrond's Council, floral for Lóthlorien, and a scent we called “horse” for the Balrog. Interestingly, horse was the only scent that proved successful. Fir, it turned out, evoked images of mountain forests for some audience members and urinals for others. We discovered what any scent scientist (and there is an entire industry devoted to the science of scent) could have told us: different people have wildly different perceptions of the same molecules hitting their scent receptors. Many are hypersensitive to certain scents and can become ill from them. Furthermore, using aromas, making them appear and disappear reliably, can involve some tricky air-handling. The most successful way to do this is with scent dispersers at each seat, but they may be more expense and trouble than they are worth. However, I do see the possibility of effectively using a subliminal signature scent for a production.

Every now and again, serendipity decrees that all the pieces I have described above fall perfectly into place, and my contribution as the special effects designer becomes an essential part of a show's artistic success. Such was the case with one of the most satisfying collaborations of my career — the 1994 Broadway production of An Inspector Calls.

Director Stephen Daldry tasked me with designing a rainstorm which was, for all intents and purposes, a character in the show, an undertaking that was made possible only because of the exceptional talents of the other members of the artistic team. Lighting designer Rick Fisher not only lit the falling rain I had designed from optimal angles, but also lit the splash-line on the deck. Sound designer T. Richard Fitzgerald then amplified and augmented the sound of that well-lit rain hitting the deck. I only made the rain, but the lights and sound revealed it to the audience through two senses.

And then, to really nail the effect, we added in the sense of touch. To achieve this, we cued the rain to begin falling even before the curtain went up. This created a reservoir of moist air, which, as the curtain rose, rolled out in great wafts of cool, damp mist onto the audience. The fourth wall had been breached before the actors said a single word. The rain had the first monologue of the show, and it set the tone for everything that came afterward. It was as if the rain had itself become an actor — the whole had truly become more than the sum of its parts.

Reprinted from the Fall 2008 issue of Protocol, the journal of the Entertainment Services and Technology Association.