The Lego Maze Caveat: Why Your Slime Mold Usually Cheats

Lego mazes look clean in photos, but many are not real barriers to your blob. Physarum exploits seams, climbs moisture films, and bypasses intended lanes.

If you do not control these leaks, your maze result is mostly container geometry noise.

How cheating happens

Three routes are common:

1. Seam bypass through tiny brick crevices.
2. Over-the-wall crawl when lid clearance is high.
3. Surface shortcut on unintended wet plastic paths.

Your blob is not breaking rules. It is following the easiest physical route available.

Common setup mistakes

• Wall height too low relative to lid gap.
• Uneven pressure between bricks creating channel seams.
• Agar or droplets touching barrier tops.
• Uncontrolled humidity gradients across the dish.

Each one creates an artificial shortcut.

Fair-maze design rules

• Keep wall-lid clearance tight enough to prevent overtop movement.
• Press seams tightly and inspect with side light before inoculation.
• Confine moisture to intended lanes.
• Standardize starting inoculum position and food node geometry.
• Repeat runs with identical build parameters.

Optional reinforcement

Light can act as a soft boundary because blobs avoid strong illumination. Used carefully, this can reduce barrier escapes, but keep it consistent across trials or you create another confound.

Why this matters

Maze experiments are often used to claim optimization behavior. If your physical barrier leaks, you are not testing route choice, you are testing crack-finding.

A fair maze is a mechanical engineering task first, and a cognition experiment second.

Related reading: Maze Solving, Brainless Problem Solving, and Experimental Design.