What wipes in Star Wars teach us about the brain and also interface design

11.28, Friday 23 Apr 2021

This seven minute video opened my eyes to the sophistication of the editing in Star Wars, and it connects to some intriguing cognitive quirks that should be better known by designers.

Watch on YouTube: Film editing psychology - screen wipes in STAR WARS by Rob Ager (7 mins 18 secs).

It focuses on the unusual approach that Star Wars has to scene transitions, often using a curtain sweeping visual impression - as in a cheesy PowerPoint presentation - rather than a regular cut. Regular cuts work like this:

Most movies don’t use screen wipes but instead rely on the standard scene transition editing approach. As one scene ends, there tends to be a momentary gap after a section of dialogue or action comes to completion. The gap establishes the closure of the scene and then a cut to a new scene is introduced, which tends to involve an initial introductory gap before dialogue and action commences again.

That gap! In one quite normal cut: Note the 6 second gap separating the dialogue.

But (as the video shows) if you remove the gap, the easing between scenes, it’s too abrupt.

The gap is not required with a wipe: there is only a 2 second dialogue gap between these two scenes which uses a fast screen wipe instead of a straight cut.

It’s not really about saving time. The maintenance of emotional engagement from scene to scene is what counts.

Ager’s YouTube video has a ton of examples (there are 23 such wipes in Star Wars. Most movies use… none). In particular, there are shaped wipes.

Straight-edge wipes dominate at the beginning of the movie. Circular wipes - opening an aperture to the next scene - dominate over the final 30 minutes.

I love one wipe in particular: there’s a scene where the rebel fighters are being briefed, and the movie move us quickly to the scene of the action:

This circular wipe begins at the part of the screen where the Death Star is positioned, like the Death Star itself is forcing itself on screen.

I mean, maybe you don’t consciously notice it when you watch the movie.

But my goodness, when you look out for, you can see the effect on your own attention and sense of story, and that wipe is deft af.

(Marcia Lucas won the Best Film Editing Oscar in 1977 for her work on Star Wars.)


Why do wipes work so successfully? (More examples of wipes on Wikipedia.) I can’t prove this, but I have a hunch.

The brain has a limited amount of resources, so it has to choose what’s going to be regarded and what’s going to be ignored. The feeling of this resource allocation is what we call attention.

Attention is the topic of Mind Hacks chapter 3, and there’s a particular idea I want to pick up on called object files. If you have the book and want to read more, go to Hack #36: Feel the Presence and Loss of Attention. (Here’s a search for ‘object files’ in Mind Hacks at Google Books.)

When you see an object, the brain automatically tracks it, setting up a file: a kind of invisible sticky tag on the object.

The benefit? When the object goes behind something, the tag is still attached – so when it reappears, you know it’s the same object.

What I’m fascinated by is the brain’s automatic allocation and deallocation of these tags.

Because:

  • while seeing an object creates a tag for it,
  • and seeing an object slide behind something does not remove the tag,
  • seeing an object shrink to a dot, as if it is receding into the distance, does indeed automatically remove the tag. Attention is automatically deallocated.

So the brain is full of these automatic attention allocation and deallocation heuristics. Seeing an object shrink to a dot is one such trick.

And it isn’t just individual objects. I wrote last month about the Doorway Effect: Your memory resets when you walk through a door. (See: Clues for software design in how we sketch maps of cities.)

When you walk into a new room, your brain automatically deallocates attention from the previous room, readying you for whatever comes next. Helpful! The Doorway Effect doesn’t require a physical trigger. It even works on screen, with a visual representation of a doorway.

Sounds like a Star Wars wipe!

So here’s what I think is going on: Without a wipe, the brain needs a couple of seconds to spin down and spin up, otherwise the shift in scene is too abrupt. But using a wipe, there is some kind of cognitive cue that interacts with the brain’s automatic attentional system, efficiently triggering the process of attention deallocation/allocation, making the whole transition more efficient.


But the brain’s attentional system is half the story.

My mental model for what is going on is that there is the attentional system and there is the emotional system.

While the attentional system makes step changes, triggered by heuristics as discussed above, the emotional system is continuous with no such resets.

But the emotional impact of a visual impression does still decay over time.

With a Star Wars Wipe, the scene transition is 4 seconds quicker – meaning the emotional state is still fresh, and so there is greater emotional continuity from scene to scene. Powerful!

As I said – a hunch! But it makes sense to me.


Interface design.

I’m thinking about this because I’m thinking about software, and particularly how we move between contexts: desktops, windows, apps, websites, views within apps, and so on.

We know that some UIs feel intuitive and satisfying, and others are baffling.

Thinking about the iPhone, there are tiny visual cues all over the place: tapping on an app will zoom it to fill the screen. Well that must perform something like the Doorway Effect. Moving around inside an app is often a matter of scrolling up and down (a transition with no visual edge) and panning side to side (a transition with a hard visual edge). I don’t know what these do to the attentional system but I know, simply from introspection, that this is more “satisfying” than a flash that abruptly updates the display or, say, a pseudo-3D rotating cube effect.

We’ve gotten to this place of success by modelling user interfaces on the physical world: the computer desktop, windows with their object permanence, “Material design” and so on. But my take is that the physical metaphor isn’t what’s important. It’s that, by adopting the physical metaphor, we also tapped into the brain’s heuristics for how to structure information.

So I’m curious about the attentional ergonomics (let’s call it that) of user interfaces.

And, if this is a valid way to think about software, I’d like to start using this cognitive approach to design software. Don’t take physical metaphors too seriously, but work directly with the deeper cognitive heuristics. Then, taking into account the emotional system too, where would that take us? A new grammar for interfaces?

I’m sure this has been studied by HCI groups for years, so apologies for being obvious. But this is where my head’s at right now, so if you know the appropriate keywords for me to read up on the research, please do suggest.

Follow-up posts:

If you enjoyed this post, please consider sharing it by email or on social media. Here’s the link. Thanks, —Matt.

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