MPRT - Moving Picture Response Time
Updated
Sometimes "response time" is evaluated in terms of MPRT (Moving Picture Response Time). This is not a measurement of how fast a pixel changes color, but rather for how long a pixel is continuously visible. Even when a pixel finishes changing color, it can remain in that same state until the next time the screen refreshes. It's commonly used when trying to represent visible motion blur caused by this persistence. It is often limited by refresh rate, but specific blur reduction technology can often lower it further.
One such blur reduction method is to simply strobe the backlight, i.e., turn it off after the image is displayed, then turn it back on when the screen fully refreshes again. This specific method affects overall screen brightness (less time illuminated leads to a dimmer picture) but effectively reduces image ghosting and afterimage issues. It also creates a generally smoother picture from a visual standpoint.
Some monitors offer an "MPRT" mode which signifies how the blur reduction technology is applied. In many instances, the mode it is set to can affect other monitor performance characteristics, such as brightness (as noted above).