What are the symptoms of impairment assets?

Decrease of assets price in the market and while revaluation the amount decreased in the market, generally happens due to economic recession, is recognized as impairment. It's a expenditure.

Well, I don't have a100% correct answer, but I think: 1.
Productivity decrease in high percentage than expected.
2.
New technology invented that decreased the market value of the asset (apply on machines for example) 3.
Future economic benefits are less than originally expected (for intangible assets for example)   What do you think?   Regards, Mohammad