心地とインターフェース

I use both ChatGPT and Claude in my daily life.

They have gradually taken on different roles: I tend to use Claude for work and ChatGPT for personal things. I do not want to settle on just one. They have different qualities, and my work gives me a reason to keep up with both, so I would like to keep using them if I can.

If you list their features, they are quite similar. Researching things, organising thoughts, writing, coding. I can ask either of them to do much the same things, but I think they feel quite different as tools.

Digital tools have something like a texture too.

With a physical tool, that feeling comes from its colour, shape, material, finish, weight, and so on. In a digital tool, perhaps those things are replaced by how it looks, moves, sounds, vibrates, and responds in words. We are actually touching a smooth touchscreen, yet we somehow sense qualities such as lightness or weight, softness or firmness.

One thing that stays with me when I use ChatGPT is the haptic feedback while a response is being written and when it finishes. In the app, the vibrations are small, but they have a fairly definite feel. They tell me “I’m writing” or “I’m done” without my having to keep watching the screen. As a feature, it works well too.

At the same time, I feel a little sense of life in it. All that is happening on screen is text being generated, but when the vibration reaches my body, it feels as though something is there on the other side.

ChatGPT’s conversational tone is fairly casual. Perhaps I feel that especially because I mostly use it for personal things. I ask about travel, talk through things I am unsure about, and sometimes chat about nothing much at all. It quickly settles into the way I speak.

Meanwhile, ChatGPT’s interface and the elements that make up its brand feel quite structured to me.

OpenAI’s 2025 brand refresh was led by its in-house OpenAI Design Studio. Studio Dumbar/DEPT® contributed to the visual, motion, and sound design, while the custom typeface OpenAI Sans was made in collaboration with the type design studio Dinamo.

The design guidelines describe OpenAI Sans as a typeface intended to balance technical precision with human warmth. The familiar Blossom symbol, too, is said to combine the warmth of circles with the precision of right angles. There are detailed rules for the logo’s proportions and spacing.

To me, the casual friendliness of the conversation seems to sit on top of a solid, dependable structure.

Claude feels a little different to use.

Its haptics are subtler than ChatGPT’s, and the text appears in a quiet flow. Where ChatGPT gives me a relatively clear sense that a response has arrived, Claude feels more restrained, as though it is quietly beside me.

I also find its conversation somewhat composed and thoughtful. When I have it read long documents, organise ideas, or write code, that calm sense of distance suits my working mood.

Although its conversation and responses feel calm, Claude’s appearance is, if anything, softer than ChatGPT’s. Warm colours, serif type, and graphics such as hand-drawn illustrations give it a little sense of the human hand.

The design studio Geist worked on Anthropic’s early branding for about two and a half years. It says it sought to create a UI that put function first without losing the brand’s character, communicating both the precision of its technical work and its human-centred values.

In an interview with the in-house brand team, the team also talks about extending intelligence, warmth, plain speaking, and a collaborative attitude beyond words into illustration and motion. Claude is conceived as a presence that walks alongside someone rather than ahead of them.

That overlaps a little with my feeling that it is quietly beside me.

With Claude, not only its appearance and UI but also its behaviour is explicitly designed. “Claude’s Constitution,” published by Anthropic, is a document describing the values and behaviour it wants Claude to have. Amanda Askell, whose background is in philosophy, has been leading work on Claude’s character since before this version. She is the primary author of the 2026 Constitution. The document is also used in Claude’s training and is said to shape its actual behaviour.

Of course, that document alone cannot explain the thoughtful way of speaking or the calm sense of distance I feel. Still, knowing that the design reaches beyond colour and type into the kind of presence it should be makes me feel that the way it responds in words is part of a tool’s texture too.

Seen this way, I cannot simply say that ChatGPT is firm and Claude is soft.

ChatGPT’s UI and brand have a fairly solid structure, but its conversation is casual, and its haptics carry a sense of life. Claude has warmth in its appearance, while its text and haptics are quiet, and its conversation feels somewhat composed.

These differences show up in very small places. How text appears, how strongly a vibration comes back, which words a tool chooses, and how close it feels when it engages with us. Each difference is small, but together they begin to feel like a distinct character.

I often think about these things when I work on the branding of digital products too.

I try to think about what a brand stands for and the concrete design of its products together. I want what the brand aspires to be to carry through into the details of its appearance, behaviour, features, and expression.

When I worked at startups, I often had to make all sorts of things on my own. I would think about the brand while planning features, creating screens, and shaping the visuals and words. Then I would work with engineers on the finer details of expression and interaction. Repeating that process seems to have naturally taught me to think of brand and product as connected.

When translating a brand’s direction into screens and behaviour, I think about which elements should convey it. Even if the direction is “make it approachable,” for example, I would not make everything approachable. I might leave some firmness in the UI’s structure and bring softness into the copy. Or keep the typography composed and let photographs carry a human presence. Or put a little playfulness into motion within an otherwise quiet screen.

It feels less like deciding how soft to make things, and more like deciding which part should carry which quality.

Round shapes, soft colours, friendly words, cute illustrations, slow movement. None of these is bad on its own, but when they all come together, the character can become less distinct. Firmness somewhere can make softness stand out, and a composed appearance can balance a casual manner.

I think that care with the details of words and movement creates a tool’s texture: a sense of the brand that emerges as you use it.

Even a small change in the speed or movement of a response can make it feel lighter or calmer. Add sound, touch, and language, and tools with similar features can leave very different impressions when we use them.

Thinking about it this way, making an interface means more than creating features or the appearance of a screen. It also means adjusting the sensations it gives back when we interact with it.

Sometimes a tool just feels comfortable, without my quite knowing why. That feeling may have something to do not only with its appearance, but also with the small responses it gives as I use it.