Passive Assessment | The invisible gorilla in the room

There's a famous psychological experiment called the invisible gorilla. In it, you're asked to watch a short video of six people passing a basketball. Three of them are wearing white shirts and three of them black shirts. You're asked to count how many passes are made by the white shirts. Most people get the number of passes right. Because they're focused on this, what half the people don't see is a gorilla walk amongst the players, stop, face the camera, thump their chest, and walk off.

To half the people, this very obvious gorilla is invisible.

I recently found one of my invisible gorillas. Whilst putting a flowchart together for VALID's Tree Risk-Benefit Management Strategies, I realised my invisible gorilla was Passive Assessment.

Passive Assessment, and not Active Assessment, is a duty holder's most valuable tree risk-benefit management asset because;

• Trees with the highest risk are the easiest to find
• Anyone can do it
• It's happening in all zones, day in day out, at no additional cost
• High-use zones are being assessed more frequently than lower use zones 
• It'll be going on soon after storms