The screen in a room with other people in it

A screen is a light source pointed in a direction. Everything in this card follows from that, and almost none of it involves software.

This is the most physical card in the section and the least technical. No setting changes where a monitor is facing. The observers here are people in a room, on a call, in a doorway, or on the pavement outside a window, and what they get is determined by angles, distance and how long the thing was on screen.

It is also the card where readers most reliably overestimate the exposure. The mental image is somebody reading your screen over your shoulder with attention. The reality is somebody walking past whose eyes land on a rectangle of colour for less than a second while they are thinking about something else entirely.

What a person in the room gets

• Large text and layout. Headings, the general look of a page, whether it resembles an ordinary site or something unfamiliar. This is the layer that survives a glance.
• Sudden changes. Movement attracts eyes. A window opening, a page loading, you switching tabs quickly when someone comes in. The switch is often more noticeable than whatever was being switched away from.
• Reflections. A window behind you at night, a glass cabinet, a mirror, glasses at close range. These are real but they are low resolution. A reflection carries layout and colour, essentially never small text.
• Anything you point at. If you turn the laptop to show somebody a photograph, they get whatever else is on that screen at full attention, which is a completely different exposure from a glance.
• The whole screen, on a shared call. Screen sharing is the sharpest item here by a wide margin, and it is covered separately below.

What they do not get

Small text, at any distance beyond arm's length, is gone. That covers addresses, account names, order references and message bodies. The characters in the addresses at the top of this page are exactly the class of thing a passing glance cannot resolve, and a person in a cafe two metres away is reading nothing at all.

They also do not get context. A page seen for one second with no idea what it is produces no memory, because memory needs something to attach to. Human recall of screens is poor even when people are trying, and nobody in a shared room is trying. Ask someone what was on the television an hour ago and watch how little comes back.

And they do not get persistence. Unlike every other observer in this catalogue, a person in a room stores nothing outside their own head. There is no record to request, no retention period, no export. What they have is an impression that degrades on a normal human curve, unless something made it salient.

Screen sharing is the exception

On a video call, screen sharing does not have the properties above. Everyone on the call sees the screen at full resolution, for as long as it is shared, with the ability to look carefully. Many platforms allow recording, which turns an impression into an artifact held by whoever pressed the button. Small text is perfectly readable. Notification banners land in the middle of it.

Sharing a single window rather than the whole desktop is a meaningful difference, because it excludes the taskbar, the other windows and most system notifications. It does not exclude anything that happens inside the shared window itself, and on some setups a modal dialog or a notification can still be drawn on top.

The related exposure is a screenshot taken by somebody else on the call, which is outside your control entirely and produces a file on a machine you have never seen. Screenshots and photos covers what those files carry.

What changes the answer

5 things change how much this action gives away. None of them takes it to zero, and none of them is a promise.

1. Point the screen somewhere usefulWhich way a monitor faces relative to the door, the window and the sofa is the single largest variable in this card, and it is free. It settles the question permanently rather than requiring a decision each time. It does nothing about anyone sitting beside you.
2. Do not switch away quicklyAn abrupt tab switch when somebody enters is more memorable than nearly anything that could have been on the screen. Movement is what draws attention. There is nothing to do about this except know it, and it is not a suggestion to behave in any particular way in front of anybody.
3. Share a window, not a desktopOn a call, sharing one application window excludes everything else on the machine, including the taskbar and most notification banners. It does not exclude a dialog drawn on top of that window, and it does not stop anyone recording what is shared.
4. Silence notification content before a callDo not disturb, or turning off banner previews, keeps message text out of a shared screen. This is the same setting mentioned in lending the machine and it earns its place twice. It does nothing about what is already on the screen.
5. Windows and blinds are part of thisA screen visible from outside at night is visible in a way it is not by day, because the room is lit and the outside is not. This is worth checking once. It is irrelevant in an upper-floor flat with nothing facing it.

What this card is not

This card is not about privacy filters or hardware, and it makes no claim about what any particular person would notice. It describes angles and attention.

Questions that come up

Do privacy screen filters help?

They narrow the viewing angle, which addresses the person beside you or behind you and does nothing about a screen share, a reflection, or somebody standing directly behind you looking straight on. This site does not recommend products.

How much does a passing glance actually retain?

Very little, and this card says so plainly rather than dramatising it. What survives is layout, colour and anything large. Specific strings do not survive. That is a description of ordinary attention, not a guarantee about any individual.