Effects of environmental design and police enforcement on violations of a handicapped parking ordinance.

The team picked two grocery stores with busy parking lots.

They watched how many drivers parked in the blue handicapped spots without a permit.

First they counted violations for two weeks with the old flat signs.

Then they put up tall, upright signs that stuck out above car roofs.

Next they added quick police checks twice a day.

They kept switching the signs and the police checks on and off to see what worked.

The tall signs alone cut illegal parking by more than half.

Adding two short police drive-bys each day pushed violations almost to zero.

When they took the signs away, violations shot back up.

The same pattern happened at both stores.

Bigby et al. (2009) got the same kind of win on a college campus.

They paired a small windshield prompt with police threats and raised seat-belt use 20 points.

Both studies show that a tiny prompt plus a clear penalty can change adult behavior fast.

Grace (1995) explains why the tall signs work: they make the illegal act harder to ignore.

The signs raise the effort of pretending you didn’t see the rule.

Wearden et al. (1983) used a different method—training crossing guards—but the single-case logic is the same.

Both teams kept turning the intervention on and off to prove it was really working.

You can copy this tomorrow.

Pick a rule your clients keep breaking—maybe staff leaving therapy materials out.

Put a bright, tall reminder right where the rule is broken.

Add one quick daily check with a mild consequence.

Watch the problem drop the same day.