Mice: cues they can see and use

Cues

i) Must be visible, & useful to mice. They must be far enough away to require the mice to use spatial analysis, rather than association, to solve the task. But near enough & positioned appropriately, for the mice to see and use them. And spatially specific enough to solve a spatial task. Feel-good psychedelic & animal posters stuck on the far walls of a large room ,below the line of vision of mice swimming in a high sided pool, do not qualify!
ii) We use a 2m pool, sufficiently large that I only have to place the cues just outside the walls of the pool, and the platform ~0.5m in from the side. That makes the task difficult – impossible to solve by association, and the cues are maximally visible. Although it is still obvious that mice placed near the walls have to swim to the centre to get their full bearings. There are places near the wall of the pool, where they can see 1 or 2 cues, but need all 3 to triangulate the position of the platform.
iii) For a 1m pool you have to place the cues some distance from the pool, for the task to be spatial not association. I use board 5-15 cm wide, 1m long,
Cues can consist of black stripes (vertical, horizontal, triangles) of different widths.
They need to stand out to a mouse, be positioned where they are optimally visible & angled towards the centre of the pool so they appear perpendicular to the mouse. And instantly distinguishable from each other. You can see if the mice are using them; they need 3 specific cues, and diffuse cues in the room, such as sources of light, as general orientators.

Original text: Dr Roger J Morris, 1998, with editor's notes by Richard Baker. Copyright (C) 1998 RJ Morris & HVS Image. Reproduced unchanged. Copyright Richard Baker© 2013. All Rights Reserved.