By Helen Soteriou | BBCNews

Disney Imagineers have added a fifth sense to the newest attractions at Epcot Center. The sense of smell will be added to scores of other special effects in a new generation of Disney shows now being designed for Future World and the World Showcase pavilions.

Working with the Imagineers at WED Enterprises in California, Bob McCarthy has developed "a smellitzer machine", to add the aroma of everything from an erupting volcano in the Universe of Energy show to the tantalizing smell of a barbecue of the fragrance of orange blossoms. Each will be keyed to a particular show scene to enhance the realism of experiences in the Future World and World Showcase.

WED designers are collecting scents from suppliers all over the world and blending them to produce the desired effect. So far, more than 300 odors have been tried, but more than 3,000 will be tested before the final choices are made. The smellitzer operates like an air cannon, aiming the scent up to 200 feet across a room toward an exhaust system. Guests traveling on the moving vehicles will pass through the scene as the appropriate scent drifts across their path. Regulated by computer, the scent can be triggered for a fresh aroma just prior to each vehicle’s arrival.

According to McCarthy, the use of smell has fascinated the entertainment industry for a long time. "Back in the fifties, Mike Todd developed a process called ’smell-a-vision’," McCarthy said. "The idea was to release certain scents into the theatre as the visual counterpart was shown on the screen." McCarthy, who worked with Todd on the project, claims there were many problems with "smell-a-vision." "The main problems was that odors tended to linger in the air, and after a while they all blended together," he said. "We couldn’t get the scents in and out of the theatre quickly enough." At Epcot Center, the situation will be different because the audience will be moving through each of the many experiences in each pavilion.

Some of the most unusual scents will be in the Land pavilion at Epcot Center. Here, the visitors will experience tropical vegetation, rain forests, deserts; some of the great terrain found on Earth. Of course, Disney "Imagineers" plan to supply all the appropriate smells. Guests traveling through a farming scene may detect a faint animal smell. In another scene, an orange grove will smell like the real thing. Still another effect calls for the smell of damp earth.

Some of the smells will hardly be noticeable to most people. The aroma will be there, but the sensory perception may not be a conscious one. The WED engineers have learned how to regulate the strength or intensity of the odors used. A whole generation of unique techniques, special effects and transportation systems are being developed for Epcot Center.