watermaze.org: the friendly field guide to the Morris water maze
Pool set-up
How to set up a Morris water maze pool
This short film shows how to set up a Morris water maze pool. It covers the pool diameter, three visual cues and where they go, overhead lighting for tracking, white washable paint to make the water opaque, aligning the cylindrical platform with the tracking software, and checking that the water is at 25 °C before the temperature probe is removed.
This week: measures
The chaining annulus: when a neat circle is not a map
Some animals cut their escape time by swimming round and round at the platform's distance from the wall until they bump into it. Latency falls, path length falls, and on those numbers alone it looks like learning. It isn't. That pattern is chaining, and the chaining annulus is the ring that catches it.
Read how the annulus is defined, how it differs from circular zones and platform counters, and why strategy measures belong beside the stopwatch. The Morris probe-trial essay stays close by for the memory side of the story.
Start here
New to the water maze?
What the maze is, where it came from (there is more than one Morris!) and how to plan your first experiment.
Tip! Test anxiety and activity before the water maze, not after. (paraphrasing Dr Roger Morris)
Pool & room
How big should the pool be?
The original notes say about 1.8 m for rats with a 10 cm platform, and 1 to 1.5 m for mice with a 5 to 10 cm platform. Here's why size matters.
Where do the cues go?
Out of the pool, around the room, and at least three of them. Plus the cues you didn't mean to give: the camera, the lights and you.
Mice vs rats
Mouse hints from Dr Roger Morris
Mice are not small rats. Mesh platforms, water temperature, time on the platform, and getting them used to being handled.
Protocols
How many trials a day?
The 1998 mouse notes found two trials a day nearly as good as four. How to plan trials, intervals and probe days.
Measures
Which measure should I report?
Escape latency is the classic, but it mixes memory with swim speed. Path length, heading angle, Gallagher proximity and search strategies each tell you something different.
Statistics
Which probe measure is most sensitive?
Maei and colleagues (2009) compared quadrant and zone occupancy, platform crossings and proximity to the old platform. What they found, and what it means for you.
Troubleshooting
My animals float, or hug the wall. Now what?
Floating, thigmotaxis and flat learning curves: what they can mean, and what to check first.
Variants
Barnes, Atlantis, radial arms and human VR
The water maze has relatives. When a dry maze, a rising platform or a virtual pool is the better choice.
Since 1998
What is the Morris water maze?
"It is about place-learning and memory. Rats and mice are natural swimmers." Read the original introduction from watermaze.org (1998–2013).
Protocols
Protocols
Learning trials, cued and hidden platforms, reversal and a methods section you can adapt.
Sponsored by HVS Image - video tracking for Morris Water Maze
From original material by
Richard Baker
Original sponsor line and credit, reproduced unchanged. Copyright Richard Baker© 2013. All Rights Reserved. The full original site is kept at the original watermaze.org.
New to the test? HVS Image has a short explainer, what is the Morris water maze, and an overview of Morris water maze analysis measures.