Protocols
Reversal learning: moving the platform
Can the animal let go of what it learnt and learn something new?
Once an animal knows where the platform is, you can move it. Now the question becomes one of flexibility: how quickly does it give up the old spot and find the new one? Dr Richard Anderson's notes describe reversal as a way "to examine flexibility of learning" (see cued and hidden platform training), and Dr Roger Morris's 1999 essay describes a reversal day in detail and suggests that a day-one difference between groups may be one of survival strategy, not spatial learning. It's worth reading the essay before you interpret your first reversal day.
Questions people ask
Can Direct Path be applied to a previous platform position, for example in reversal?
Yes. The six classifications are also evaluated for each other calibrated position and reported separately, so you can see whether the first approach went to the old or new location. Absence of a Direct Path classification does not by itself mean impaired navigation.
More detail
Yes: a Direct Path is a near-straight first approach (path ratio ≤ 1.2), and HVS Image evaluates the same six classifications for every other calibrated position, such as the previous platform in reversal. Each other position uses a destination and close encounter zone of the same size and the same criteria. Its meaning depends on the design: a previous platform in reversal, or positions indicated by competing proximal and distal cues. In probe trials the target measures use the position recorded as the trial's target. Direct Path complements latency and path length rather than replacing them.
Going deeper
A long latency without any Direct Path classification gives less evidence that the trial began with an accurate approach; check other measures. No classification but a low path ratio means an efficient route that did not meet the criteria.
To compare old and new platform areas, see using circular zones in Morris water maze analysis.
Spotted a mistake, or know a better source? Tell us and we'll fix it and say so on our corrections page.