Definition: The Latency is also known as Escape Latency and is a measure of learning in Morris water maze. It is the time it takes the subject to find the platform. Prior to the first Cartesian positional video tracking in HVS Image’s VP110 reported by Morris 1984 Escape Latency had been measured by stopwatch, a method long established as having both random and systematic observational error [e.g. by Sanford, 1888] which differs between laboratories and observers. This has more recently been characterized in “Performance Test Standard PTC 19.1-2005”.
The HVS Image VP110 eliminated this error by use of a hardware crystal oscillator. Later, attempted use of the personal computer’s internal clock by generic non-HVS systems has resulted in “millisecond precision” using timing units that the software reports that do not necessarily correspond to “millisecond accuracy”. This difference has been reported as part of the “replication crisis” e.g. by Plant 2015 – an issue that has been anticipated and eliminated by all HVS Image systems without separate crystal hardware by real time cross checking of system clock measurements with hardware based marker measurements.
Other artifacts eliminated in the family of HVS Image Tracking Systems include “automatic start” artifacts, which occur when the software timing clock starts as the experimenter’s hand enters the arena (but before the animal is released), and platform location artifacts, where the arrival at the platform is not triggered by the animal’s spatial position in the video field, but by variable and semi arbitrary human input which varies not just from experimenter to experimenter and laboratory to laboratory, but even over time with the same experimenter.
Separately from this it is important to understand that Escape Latency is confounded by swimming speed, which is not necessarily a cognitive factor.
First implemented in HVS110 in 1984
Please cite this permalink in any publication using this measure
MLA. Baker, M. R. “How is latency measured in Morris water maze video tracking systems?” Behavioral Tracking Knowledgebase., Aug. 2017 Web. 7 August 2017. http://hvsimage.com/permalink/escape_latency_in_morris_water_maze/
APA. Baker, M. R. (2017, Aug). How is latency measured in Morris water maze video tracking systems? Retrieved from http://hvsimage.com/permalink/escape_latency_in_morris_water_maze/
Chicago Baker, Mark. “How is latency measured in Morris water maze video tracking systems?”, HVSImage.com. http://hvsimage.com/permalink/escape_latency_in_morris_water_maze/ (accessed August, 7, 2017).