Why do online exams allow only one monitor?
Every major online exam delivery system restricts you to a single display, and most say so in plain language. Pearson VUE's OnVUE requires one display screen only, with multi-monitor setups not permitted. ProctorU permits a single monitor when testing, with all others disconnected. ETS states that dual screens or multiple monitors are not allowed, and that a laptop must use its built-in monitor. The Duolingo English Test's published policies tell you to remove extra screens and devices from the testing area entirely.
The reason is structural. An online exam is proctored through a screen share and a webcam: the vendor watches one screen and one room. A second display puts exam content somewhere the screen share does not cover and the camera may not see - so the rules treat every extra screen as outside the verified environment, whether it is an extended desktop monitor, a touchscreen display, or a television across the room.
This page covers the published picture in general terms: the exact rule each vendor publishes, what counts as an extra display, where in the exam-day journey the display rules get checked, what happens if your setup fails one of those checks, and the official preparation steps. Every claim comes from the official documentation of five delivery systems: Pearson VUE OnVUE, ETS at home, ProctorU, the Duolingo English Test, and Honorlock.
The rule each vendor publishes
Pearson VUE's OnVUE publishes the most compact version. Its program pages list minimum requirements - Windows 10 or macOS 14 or higher, a working webcam, microphone, and speaker with no headphones or headsets, a stable internet connection of at least 6 Mbps download and 2 Mbps upload, and the ability to close all applications except OnVUE - and in the middle of that list sits the display rule: one display screen only, with multi-monitor setups not permitted. A separate prohibited technology list then covers secondary or touchscreen displays, with the instruction to disconnect and cover them if they are not removable.
ProctorU's official equipment requirements state the rule as a direct limit: you will only be permitted the use of a single monitor when testing, and all others must be disconnected. The same article handles the closed-laptop case that most dual-screen desks actually use - an external monitor connected to a closed laptop should be set to mirror the display and should be connected directly to the computer, and candidates should avoid using a docking station.
ETS writes the rule into its at-home computer requirements: dual screens or multiple monitors are not allowed, and if you are using a device with a built-in screen, like a laptop, you must use its built-in monitor. The same list prohibits multiple keyboards and requires a laptop's built-in keyboard to be the one used. The Duolingo English Test's published Test Policies, Rules, and Requirements approach it from the room side: remove extra screens and devices from the testing area, use only one keyboard, mouse, and phone, and position the phone camera so it captures your head, shoulders, screen, and keyboard.
Honorlock publishes the in-session half of the rule. Its BrowserGuard page describes software that restricts access to other websites, browsers, and applications, disables keyboard shortcuts and functions, removes toolbar and menu options, and blocks and flags the ability to minimize the browser display screen - so the exam window stays fixed, full, and visible for the whole session.
What counts as an extra display
Read the five rule sets together and a single definition emerges: an extra display is any surface other than the one monitored screen where a picture could appear. The obvious case is the second monitor on a dual-screen desk - the extended desktop that every vendor's single-display rule names directly. OnVUE's prohibited technology list adds a less obvious case: touchscreen displays, which draw the same prohibition even when they are the kind of screen built into a drawing tablet or an all-in-one desk device.
The closed-laptop arrangement counts too, and it is the one candidates most often assume is fine. Docking a laptop and driving two external monitors is a multi-monitor setup under OnVUE's rule and a disconnected-monitor problem under ProctorU's. ProctorU's published workaround is narrow and specific: one external monitor, set to mirror the display, connected directly to the computer, with no docking station. ETS is stricter still - if the device has a built-in screen, that built-in monitor is the one you must use.
The room itself is part of the definition. The Duolingo English Test's policies require extra screens and devices removed from the testing area, which covers the wall-mounted television and the spare monitor on the other desk. The published rules are written to cover any arrangement that puts the exam picture on a second surface - whether that surface extends the desktop, duplicates it, or simply sits within view. If a screen is not the one being monitored, the rules treat it as out of bounds.
Why the rules exist: one screen is the whole story
Online proctoring rests on a single arrangement: the vendor watches one verified environment for the length of the exam. ETS describes the session plainly - your entire test session is recorded and monitored by a human proctor, and during the test the proctor monitors you via video camera and your computer screen to ensure you follow all testing procedures. PSI's exam-experience guide describes the same pattern, with its proctoring team monitoring through screenshare, webcam, and microphone to keep testing conditions fair.
That arrangement only works if the screen under monitoring is the whole story. The screen share shows the proctor what is on the monitored display; the webcam shows who is sitting in front of it. A second display breaks the join between those two views: content on the extra screen is outside the shared picture, and a candidate reading from it is, on the proctor's recording, simply a person looking slightly away from the camera.
This is why the single-display rule sits in the same requirement lists as the virtual-machine and remote-access prohibitions. Those rules guarantee the monitored machine is real and directly controlled; the display rule guarantees the monitored screen is the only one in play. Together they define the verified environment the exam's integrity rests on - one real machine, one screen, one candidate, all inside the vendor's view.
Where the display checks happen
The first checkpoint happens before exam day. OnVUE requires candidates to run and pass its System Test on the same device and network they will use on exam day - which means the display arrangement you test with is the one you are expected to sit with. ETS has candidates run the Equipment Check from the ETS Secure Browser, with failed parts shown as red triangle status indicators, and requires every issue resolved and the check passed before check-in.
The second checkpoint is check-in itself, and this is where the display rules get a physical inspection. ETS's proctor reviews the exam rules, requests access to your computer screen for monitoring purposes, asks you to use either a handheld mirror or a cell phone to show your computer screen, and then asks for a 360-degree view of the room including your tabletop surface - a sequence that puts the screen, the desk, and the rest of the room in front of the proctor before the exam begins. OnVUE's check-in combines its required technology checks with ID photos and a 360-degree room scan to confirm your environment is ready. The Duolingo English Test builds the same idea into the whole session: its policies require the phone camera to capture your head, shoulders, screen, and keyboard, so the display in use is on camera from start to finish.
The third layer is the session itself. Once the exam is running, the screen share keeps the monitored display in front of the proctor or the monitoring system - ETS states the proctor watches both you and your computer screen for the duration. Honorlock's BrowserGuard adds the software layer described on its product page: the browser display screen cannot be minimized without being blocked and flagged, other applications are restricted, and keyboard shortcuts are disabled, so the exam window holds the screen for the entire sitting.
If your setup fails a display check
The published outcomes depend on when the problem surfaces, and the pre-exam check is the gentlest case. ETS's design assumption is that equipment problems are found early: you run the Equipment Check, resolve every issue shown in red, and pass it before checking in. A display problem caught there costs an evening of rearranging, not an exam.
At check-in, the consequences harden. OnVUE's program pages warn before booking that all test takers must ensure they can meet the minimum requirements, and that failure to do so on exam day can result in immediate exam cancellation and forfeiture of your exam fee - and the same warning repeats at check-in: if any requirement is not met, you cannot test, and your fee will be forfeited. One display screen only is on that minimum-requirements list, so a multi-monitor setup found at check-in lands on the forfeiture rule, not on a warning.
ETS publishes the same edge in its own words: the at-home requirements page opens by telling candidates that if the computer and testing room do not meet the requirements on test day, they will not be able to test and will not receive a refund or a free reschedule. Each program sets its own policy, but the direction across every vendor is the same - display rules are eligibility rules, and the only cheap place to discover a problem is the vendor's own check, run on the real setup, before exam day.
The edge cases candidates ask about
The closed laptop on a dock is the most common real-world setup, and the vendors split on it. ProctorU publishes the accommodation: one external monitor connected to a closed laptop is acceptable if it is set to mirror the display and connected directly to the computer - docking stations are to be avoided. ETS publishes no such accommodation: its rule says that if the device has a built-in screen, you must use the built-in monitor, which settles the question for GRE and TOEFL at home.
The screen you cannot unplug is the second common case - an all-in-one desk unit, a wall-mounted display, a television in the room. OnVUE's prohibited technology entry for secondary or touchscreen displays carries the instruction directly: disconnect and cover if not removable. The Duolingo English Test's room-side version requires extra screens and devices removed from the testing area, and where removal is genuinely impossible, the practical reading of the published check-in inspections - the room scan, the mirror or phone screen check - is that every screen in the space will be looked at before the exam starts.
The shared thread through all three cases is that the published rules leave no gray zone to negotiate. One display in use, everything else disconnected, removed, or covered - and the vendor's own check run on exactly that arrangement before the day it counts.
The published preparation checklist
Read across all five vendors, the official guidance converges on one checklist. Start with the machine: a supported operating system - Windows 10 or later, macOS 14 or later for OnVUE, Mac OS 11.0 or later for ProctorU - with every application closed except the delivery software.
Then reduce the desk to one screen. Disconnect every monitor except the one you will test on; on a laptop, plan to use the built-in display unless your vendor publishes a closed-laptop arrangement, in which case follow it exactly - one external monitor, mirrored, connected directly. Clear the room the same way: extra screens and devices out of the testing area, one keyboard, one mouse, and the phone that serves as the second camera where the vendor requires one.
Finally, prove it before it counts. Run the vendor's own check - the OnVUE System Test, the ETS Equipment Check - on the same device, the same display arrangement, and the same network you will use for the real session, fix everything it flags, and run it again shortly before the exam. Every vendor's documentation points the same direction: the environment check exists so that exam day holds no surprises.
If the Sitting Itself Is the Problem
A single-display rule is a solvable problem: the vendors publish the rules, the checks, and the consequences, and nothing in this page comes from anywhere but their own documentation. The harder problem is the exam on the other side of the checks - the proctored test itself, on a deadline, with a result that decides your next step.
That is the problem Exam Assist works on. If you have a proctored exam coming up and the sitting itself is the risk, send the exam, your window, and your deadline. You get an honest feasibility answer, and the service fee is due only after your result posts.
For more of this series in the same general-terms format, see our guides to why online exams block virtual machines, what to expect at remote exam check-in, and the vendor overviews for OnVUE, Honorlock, and the Duolingo English Test.