Carl, a young psychic, has an application at home to practice and hone his mental powers. It’s not named in the film, so I’m going to call it DuoMento. We see DuoMento in use when Carl uses it to try and help Johnny find if he has any latent psyhic talent. (Spoiler alert: It doesn’t work.)
DuoMento challenges its users with blind matching tests. For it, the "thought projector" (Carl) sits in a chair at a desk with a keyboard and a desktop monitor before him. The "thought receiver" (Johnny) sits in a chair facing the thought projector, unable to see either the desktop monitor or the large, wall-mounted screen behind him, which duplicates the image from the desktop monitor. To the receiver’s right hand is a small elevated panel of around 20 white push buttons.
For the test, two Hoyle playing cards appear on the screen side-by-side, face down. Carl presses a key on his keyboard, and one card flips over to reveal its face. Carl concentrates on the face-up card, attempting to project the identity of the card to Johnny. Johnny tries his best to receive the thought. It’s intense.
When Johnny feels he has an answer, he says, "I see…Ace of Spades," and reaches forward and presses a button on the elevated panel. In response, the hidden card flips over as the ace of spades. An overlay appears on top of the two cards indicating if it was a match. Lacking any psychic abilities, Johnny gets a big label reading "NO MATCH," accompanied by a buzzer sound. Carl resets it to a new card with three clicks on his keyboard.
Not very efficient
Why does it take Carl three clicks to reset the cards? You’d think on such a routine task it would be as simple as pressing [space bar]. Maybe you want to prevent accidental activation, but still that’s a key with a modifer, like shift+[space bar]. Best would be if Carl was also a telekinetic. Then he could just mentally push a switch and get some of that practice in. If that switch offered variable resistance it could increase with each…but I digress since he’s just a telepath.
A semi-questionable display
I get why there’s a side-by-side pair of cards. People are much better at these sorts of comparison tasks when objects are side-by-side. But ultimately, it conveys the wrong thing. Having a face down card that flips over implies that that face-down card is the one that Johnny’s trying to guess. But it’s not. The one that’s already turned over is the one he’s trying to guess. Better would be a graphic that implies he’s filling in the blank.
Better still are two separate screens: One for the projector with a single card displayed, and a second for the receiver with this same graphic prompting him to guess. This would require a little different setup when shooting the scene, with over-the-shoulder shots for each showing the different screen. But audiences are sophisticated enough to get that now. Different screens can show different things.
At first it seems like Johnny’s input panel is insufficient for the task. After all, there are 52 cards in a standard deck of cards and only 20 buttons. But having a set of 13 keys for the card ranks and 4 for the suit is easy enough, reduces the number of keys, and might even let him answer only the part he’s confident in if the image hasn’t quite come through.
Does it help test for "sensitivity"?
Psychic powers are real in the world of Starship Troopers, so we’re going not going to question that. Instead the question at hand will be: Is this the best test for psychic sensitivity?
I do wonder that having a lit screen gives the receiver a reflection in the projector’s eyes to detect, even if unconsciously. An eagle-eyed receiver might be able to spot a color, or the difference between a face card and a number card. Better would be some way for the projector to cover his eyes while reading the subject, and dim that screen afterward.
The risk of false positives
More importantly, such a test would want to eliminate the chance that the receiver guessed correctly by chance. The more constrained and familiar the range of options, the more likely they are to get a false positive, which wouldn’t help anything except confidence, and even that would be false. I get that when designing skills-building interfaces, you want to start easy and get progressively more challenging. But it makes more sense to constrain the concepts being projected to things that are more concrete and progress to greater abstraction or more nuance. Start with "fire," perhaps, and advance to "flicker" or "warmth." For such thoughts, a video cue of a word randomly selected from that pool of concepts would make the most sense. And for cinematic directness (Starship Troopers was nothing if not direct) you should overlay the word onto the video cue as well.
The next design challenge then becomes how does the receiver provide to the system what, if anything, they’re receiving. Since the concepts would be open-ended, you need a language-input mechanism: ANSI keyboard for typing, or voice recognition.
Additionally, I’d add a brain-reading interface that was able to read his brain as he was attempting to receive. Then it could detect for the right state of mind, e.g. an alpha state, as well as areas of the brain that are being activated. Cinematically you could show a brain map, indicating the brain state in a range, the areas of the brain being activated. Having the map on hand for Johnny would let him know to relax and get into a receptive state. If Carl had the same map he could help prompt him.
In a movie you’d probably also want a crude image feed being "read" from Johnny’s thoughts. It might charmingly be some dumb, non-fire things, like scenes from his last jump ball game, Carmen’s face and cleavage, and to Carl’s shame, a recollection of the public humilation suffered recently at his hand.
But if this interface (and telepathy) was real, you wouldn’t want to show that to Johnny, as it might cause distracting feedback loops, and you wouldn’t want to show it to Carl less he betray when Johnny is getting close, and encourage Johnny’s zeroing in on the concept through subtle social cues instead of the desired psychic ones. Since it’s not real, let’s comp it up next more cinematically.