Monitor specifications list two speed figures that are routinely confused. They describe different physical processes, and a display can be excellent at one while being poor at the other.
Refresh rate is a schedule
Refresh rate states how many times per second the panel is instructed to display a new image, and it sets the shortest interval at which anything on screen can change.
A higher rate reduces the time between updates, which lowers the delay between an input and its visible result and makes motion appear to advance in smaller steps.
It is a ceiling rather than a guarantee. If the machine produces fewer frames than the panel can show, the extra refreshes simply repeat what was already there.
Response time is a physical transition
Each pixel has to physically change state to show a new colour, and response time measures how long that transition takes from one value to another.
If the transition is slower than the interval between refreshes, a pixel is still changing when the next image arrives, so the display shows a blend of both.
That blending is what viewers see as smearing or ghosting behind moving objects, and it is entirely separate from how often the panel updates.
The two figures interact directly
A very high refresh rate leaves each frame on screen for a very short time, which means slow pixels have proportionally less opportunity to finish transitioning.
A fast panel and a modest refresh rate can therefore look cleaner in motion than a slow panel driven at a much higher rate.
Buyers who match the two figures rather than maximising one usually end up with a display that behaves as the numbers suggest it should.
Quoted response times are best-case measurements
Manufacturers commonly quote the fastest transition a panel can perform, typically between two similar shades, which is not representative of ordinary content.
Transitions between very different colours, particularly from dark to light, are usually far slower, and average figures across many transitions tell a more honest story.
Panel technology matters more than the single quoted number, since different types have characteristic strengths and weaknesses that a single figure cannot express.
Overdrive trades one artefact for another
Displays can push pixels harder to complete transitions faster, a setting usually labelled overdrive or response time in the monitor's menu.
Pushed too far, the pixel overshoots its target value before settling, producing a bright halo behind moving objects that is more distracting than the smearing it replaced.
Because the correct amount depends on refresh rate, monitors with variable refresh often need a compromise setting, which is why the middle option is usually the right one.