Containment unit

With a ghost ensconced in a trap, the next step in ghostbusting is to transfer the trap to a containment unit.  Let’s look at the interaction.

The containment unit is a large device built into a wall of the old firehouse that serves as the Ghostbusters headquarters. It’s painted a fire-truck red and has two colored bulbs above it. As they approach, the green bulb is lit. It’s got a number of buttons, levers, and cables extending into it. Fortunately for purposes of discussion, Stantz has to explain it to their new employee Winston Zeddmore, and I can just quote him.


“This is where we store all the vapors, entities, and slimers that we trap. Very simple, really. Loaded trap here. Unlock the system…” He grabs the red door lever and cranks it counterclockwise 90 degrees and lowers the door to reveal a slot for the trap.

“Insert the trap,” he continues, and a sucking sound is heard and the green lightbulb goes off and the red lightbulb turns on.

Then Stanz pulls the trap out of the slot and is able to, as he explains, “Release. Close. Lock the system.” (Which he does with the lever handle.)


Next, he presses the buttons on the front of the device, starting with the top red one and continuing with the second below yellow, explaining, “Set your entry grid. Neutronize your field…” Then he grabs the red lever on the right-hand size and pushes it down. In response, the lowest push button lights up green, the red bulb above turns off, and the green bulb illuminates once again.

Stantz concludes, “When the light is green, the trap is clean. The ghost is incarcerated here in our custom-made storage facility.”


The interaction here is all based on the unkonwn ghostbusting technology, but it certainly feels very 1.0, very made-by-engineers, which is completely appropriate to the film. There’s also that nice rhyming mnemonic to remember the meaning of the colored bulbs, which helps Zeddmore immediately remember it. And course with the red paint and thick plates, it feels really secure and conveys a sense of pith and importance. Still, if they had a designer consulting, that designer would most likely tell them talk about a few aspects of the workflow.


First, why, if there’s no breakpoint between the entry grid and the field neutronizer, can’t those two be consolidated into a single button? A gridtronizer? While we’re on the buttons, why is that third one looks like a button but acts just like a light? If it’s not meant to be pressed, let’s make it an indicator light, like we see on the trap.

Similarly, why do they have to press that last lever and wait for the green light? I get that a variety of controls feels better to convey a complicated technology that’s been hacked together, and that would be appropriate for a user to understand as well, but it seems error-prone and unnecessary. Better would be another pushbutton that would stay depressed until the unit was doing whatever it was doing behind the scenes, and then release when it was done. It could even be consolidated with the gridtronizer.


But while we’re including automation in the process, why would the ghostbuster have to press anything at all? If the unit can detect when a ghost has been sucked in (which it does) then why can’t it do all the other steps automatically? I know, it would be less juicy for the audience’s sense of ghostbusting technological complexity, but for the “real world,” such things should be fully assistive:

  1. Insert trap (which gets locked in place)
  2. Watch the machine’s lights indicating its four steps
  3. Remove unlocked trap.

You might think for efficiency to have the trap removed immediately, but you really want the Ghostbuster’s attention on the system in case something goes wrong. Similar to the way ATMs/bancomats hold on to your card through a transaction.

Lastly, there should be some sense of what’s contained. In this scene there’s just Slimer in there, but as business picks up, it gets so jammed full that when EPA representative Peck recklessly shuts it down, it…you know…explodes with ghosts. Would a sense of the contents have helped provide him with a sense of the contents, and therefore the danger? A counter, a gauge, a window into the space, a “virtual window” of closed-circuit television showing inside the unit*, or a playback showing helmet-cam video of the ghosts as they’re being captured—would all help to convey that, Mr. Peck, you do not want to eff with this machine.


*IMDB trivia for the movie says this was originally included in the script but was too depressing to visualize so it was cut. But hey, if it’s depressing, maybe that would help its users consider the ethics of the situation. (Once again, thank you, @cracked, and RIP.)

Ghost trap

Once ghosts are bound by the streams from the Proton Packs, they can be trapped by a special trap. It has two parts: The trap itself, that is roughly the size of a toaster, and the foot pedal activation switch, which connects to the trap box by a long black cord.


To open the trap, a ghostbuster simply steps on the foot pedal. For a second the trap sparks with some unknown energy and opens to reveal a supernatural light within. Once open, the bound ghost can be manipulated down towards the trap.


When the ghost is close to the trap, the Ghostbuster steps on the foot pedal again. Lots of special effects later, the ghost gets sucked down into the trap and it closes.

With a ghost contained inside, a red indicator light illuminates near the handle to let users know that a dangerous thing is contained within. (Also, it emits smoke, but I suspect that’s a side effect rather than a feature that’s been added in.) The trap can be held by the long handle or (and this is the way the Ghostbusters themselves tend to carry it around) by the cord.


The design of the trap has so many great aspects. The separate control keeps the ghostbuster a safe distance from both the proton streams, the trap, and the ghost. And the use of a foot pedal as a switch keeps his hands free to keep a defensive grip the proton gun. I should also make note of the industrial design of the thing: The safety stripes, the handle, and the shape tell of a device handmade by scientists that is dangerous and powerful.

Still, some improvements

If the activation was wireless rather than a foot pedal, the Ghostbuster would be free to move to wherever was most tactically sound, rather than constrained to standing near it. Wireless controls have their own tradeoffs, of course, and those may not be acceptable in the mission-critical scenarios of ghostbusting. If that control was also hands-free (gestural, vocal, ocular, brain) then you’d keep the goodness of the hands-free pedal.

The red light is a little ambiguous. It could just mean “power on,” which doesn’t help. Blinking should be used very judiciously, but here it’s warranted, so I’d make that blink to say “Dangerous thing contained. Release only with caution.” Let’s presume the thing automatically locks when a ghost is trapped and can only be unlocked by the containment unit (the next post). Even better might be several lights blinking, perhaps both around the trap doors and around any controls that might release the ghost, e.g. the foot pedal. You could even make it blink similarly to the “working” light animation of the Proton Packs to tie the equipment together.

One problem that’s familiar to software designers is that’s that the control is a stateless toggle, i.e. it looks and behaves the same whether you’re opening the trap or closing the trap. If the trap doesn’t automatically lock with a ghost in it, that’s a major problem. Imagine if the activator had hid behind a curtain to trap a poltergeist and wasn’t sure if he’d accidentally stepped on it. A UX 101 rule of thumb is that controls should indicate the state of the thing they’re controlling. So the pedal should have a signal to indicate whether the trap is open or closed, even though the trap itself conveys that pretty well. Even better if that signal is something that can be felt with the foot. Maybe it’s a rocker switch? (Like this Linemaster, but more exaggerated.)

Lastly, we can also presume that the trap has a power source, and that there’s a time pressure to get the trap to the containment unit before that power source dies. But where’s that information? So some indication somewhere of how much power and time is left for that would be very useful to avoid all that work (and, you know, property damage) going to waste.

Small improvements, but each would improve it and not take away from the narrative.

Proton Pack


The Ghostbusters wear “unlicensed particle accelerators” to shoot a stream of energy from an attached gun. Usefully, this positively-charged stream of energy can bind ghosts. The Pack is the size of a large camper’s backpack and is worn like one. The Proton pack must be turned on and warmed up before use. Its switch, oddly, is on the back, where the user cannot get to it themselves.

Proton-Pack-03 Continue reading


When the Ghostbusters are called to the Sedgewick Hotel, they track a ghost called Slimer from his usual haunt on the 12th floor to a ballroom. There Ray dons a pair of asymmetrical goggles that show him information about the “psycho-kinetic energy (PKE) valences” in the area. (The Ghostbusters wiki—and of course there is such a thing—identifies these alternately as paragoggles or ectogoggles.) He uses the goggles to peek from behind a curtain to look for Slimer.


Far be it for this humble blog to try and reverse-engineer what PKE valences actually are, but let’s presume it generally means ghosts and ghost related activity. Here’s an animated gif of the display for your ghostspotting pleasure.


As he scans the room, we see a shot from his perspective. Five outputs augment the ordinary view the googles offer.

1. A plan position indicator (like what you see on a radar) sweeps around and around in the upper left hand corner, but never displays anything (even when Slimer appears.)

2. A bar graph on the left side that wavers up and down until Slimer is spotted, when it jumps to maximum. The bar graph adheres to the basic visual principle of “up means more.” The bar graph is colored with a stoplight gradient, with red at the bottom, yellow in the middle, and a bright screen-green at the top. Note that the graph builds from the bottom until it hits maximum, when its glow slides to the top to fully illuminate only the uppermost block. This is a special “max” mode that strongly draws the user’s attention.

3. There is a 7-segment red LED number display just below the graph, which you might think is a numerical version of the same data, but we only see it increment steadily from 03094 to 03051 during the first scan, then after a cutaway to Ray’s face, we see it drop to 01325 and continue to increment steadily until it hits 1333, where it remains steady and begins to blink. It hits this maximum about a half a second before the graph jumps to its max.


4. In the very lower left is a red mode label reading “KER,” which blinks until the numbers hit 01333 in the second sequence, when KER disappears and is replaced with a steadily-glowing green “MAX.”

What the heck is KER? I don’t think there’s any diegetic answer. Ker might be an extradiegetic shout-out to Rick Kerrigan, who was production supervisor for Entertainment Effects Group / Boss Film Studios for the film, but that’s just a guess. Otherwise I got nothin’. Anyone else?

5. In the lower right is a blurry light that blinks red until Slimer is spotted, when it blinks the same screen-green as the bar graph, sweep, and MAX label.

Narratively, this is a tone interface, that doesn’t add anything to the plot, and only helps us experience and understand how it is the busters do their busting. As a tone interface, making these changes would help improve believability without affecting the plot.


How to better support busting

The immediate improvements you could make to this as a “real” ghostbusting tool are fairly obvious:

  • Make the plan position indicator, you know, work.
  • Have the numbers match the graph, or, if they’re actually measuring different things, put the LED display on the other side of the view.
  • I’d change the graph color indicating no-PKE to black or dark gray. Red often connotes danger, and really, if there’s no PKE, you’re safe from the supernatural. Plus the blackbody radiation spectrum has a more physical reference and is therefore more immediate.
  • You could even lose the bar diagram—which requires looking away from the view—and replace it with a line around the view that changes color similarly. This puts the augmentation in the periphery.
  • Lose the distracting blinking red light entirely. It draws attention at a time when the Buster’s eyes need to be on the view, and it’s just duplicating information already provided in a better way by the graph.

But we can do those improvements better. In the augmented reality chapter of the book, I identified levels of awareness for these devices. The ectogoggles are an example of the simplest type, of sensor display, with the sweep giving an unfulfilled promise of the second type, location awareness. We can make even bigger improvements by considering the other levels, i.e. context and goal awareness.

Context Awareness

Context awareness implies a more sophisticated system with image recognition and display capabilities. Could the paragoggles help draw attention to where on the view the PKE is most concentrated, and how those readings are trending? Of course this wouldn’t be so important when the ghost is actually visible, but if it could lead his eyes to where the ghost is most likely going to be, it would be more useful and save him even the microseconds of an eye saccade.

A second aspect of context awareness is object or people recognition. If the goggles could recognize individual ghosts, the display be improved with some information about this particular ghost—or its category—from a database. What’s its name? What methods have failed or worked in the past to control it? Even if it doesn’t know these things, it can provide an alert that it is an UNKNOWN ENTITY, which is spooky sounding and tells the Ghostbusters to be on high alert since anything could happen.

Goal awareness

Lastly, they could be improved with goal awareness. The Ghostbusters aren’t birdwatchers. They’re there to capture that ugly spud. Can it help guide each person as to the best time to gear up the proton packs (or do it for them), where to position themselves as well as the trap, and finally when and where to fire? Certainly someone as scatterbrained as Ray could use that kind of assistance.


Ghostbusters (1984): Overview

Release date: 8 June 1984, United States


Ghostbusters is the story of a group of quirky scientists who start a paranormal pest control service in New York City. Though they struggle initially, the number of infestations mysteriously increases and they begin to capture and incarcerate more and more, leading to national fame. At the same time, the charismatic Ghostbuster Peter Venkman gets romantically involved with Dana, a customer whose case happens to lead them to the center of the mystery of the increasing paranormal activity: the imminent return of an ancient world-destroying demigod called Gozer. Just as the mystery deepens and Dana becomes possessed, they are arrested and their custom-made incarceration device is powered down by an aggressive and suspicious government employee. As a result the device explodes, flooding the city with spooks even while the Ghostbusters, in jail, are helpless to do anything about it. After convincing the mayor that it is in his best interest to release them, the Ghostbusters confront Gozer and use their homemade equipment to send it back to the dimension from which it came, freeing the possessed Dana as well as her neighbor Louis, and saving the day.

Rescue Shuttle


After the ambush on Planet P, Ibanez pilots the shuttle that rescues survivors and…and Diz. We have a shot of the display that appears on the dashboard between the pilot and copilot. Tiny blue columns of text too small to read that spill onto the left. One big column of tiny green text that wipes on and flashes. Seizure-inducing yellow dots spazzing around on red grids. A blue circle on the right is probably Planet P or a radar, but the graphic…spinning about its center so quick you cannot follow. There’s not…I can’t…how is this supposed to…I’m just going to call it: fuigetry.

Federation Binoculars

When conducting reconnaissance on the bug home Planet P, Rico pauses to scan the nearby mountain crest with a pair of Federation binoculars. They feature two differently-sized objective lenses.


We get a POV for him and get to see the overlay. It includes a range-finding reticle and two 7-segment readouts in the lower corners. It looks nifty, but it’s missing some important things. Continue reading