Open field test

The question

Today's maze is all about choices. What can an empty box tell us about anxiety and movement? You're watching Morris Water Maze Software Guide, over at morriswatermazesoftware.com.

Meet the open field test

The open field is a simple, walled arena, often square, that an animal explores freely for a few minutes. Rodents prefer the walls, so time spent in the open centre is used as a gentle index of anxiety-like behaviour, while distance travelled reflects general activity.

How it runs

The recipe is short. First, light the arena evenly and keep the lighting the same for every animal. Next, place the animal in the same start position, often the centre or a corner. Then, record for a fixed period, typically 5 to 30 minutes. After that, clean the arena between animals to remove odour cues. Finally, with a divided arena, several animals can be tracked at once with one camera.

Strengths and limits

Why do labs keep coming back to it? It's quick, cheap and needs no training. It gives activity and anxiety-like measures in one session. It's a useful control for motor effects in other tests. And the catch? Centre time is sensitive to lighting, handling and time of day. Activity changes can masquerade as anxiety changes. It's a broad screen, not a specific diagnostic.

What to measure

What should you actually measure? Total distance and speed: general locomotor activity. Time and entries in centre versus border zones: anxiety-like behaviour and thigmotaxis. Time slices: habituation across the session. Inactivity bouts: freezing or resting. Two groups spend the same total time in the centre, but one only goes there in the last minute. Time slices catch that habituation difference.

The takeaway

One thing to take away: time and entries in centre versus border zones and its neighbours tell you how the task was done, not just how fast. Scripts, chapters and sources live on this page.