Tests of unconditioned anxiety — Pitfalls and disappointments

• Review of the discriminant validity of the current tests of unconditioned anxiety
• Issue with translation of the operational definition of anxiety into behavior tests
• There is no concordance between spatiotemporal and ethological parameters
• Pharmacology is neither sufficient nor necessary in the validation of behavioral tests
• Novel open space anxiety tests are proposed as alternatives to the current one.

The plus-maze, the light–dark box and the open-field are the main current tests of unconditioned anxiety for mice and rats. Despite their disappointing achievements, they remain as popular as ever and seem to play an important role in an ever-growing demand for behavioral phenotyping and drug screening. Numerous reviews have repeatedly reported their lack of consistency and reliability but they failed to address the core question of whether these tests do provide unequivocal measures of fear-induced anxiety, that these measurements are not confused with measures of fear-induced avoidance or natural preference responses — i.e. discriminant validity. In the present report, I examined numerous issues that undermine the validity of the current tests, and I highlighted various flaws in the aspects of these tests and the methodologies pursued. This report concludes that the evidence in support of the validity of the plus-maze, the light/dark box and the open-field as anxiety tests is poor and methodologically questionable.