Fig. 1: Human versions of the reviewed cross-species anxiety paradigms.

A Elevated plus maze: mixed-reality setup in which human participants explore a plank over a deep drop and another one that rests on a rocky ground. B Open field test. Participants explore, in reality or virtual reality, a large space up to the size of a soccer pitch. C Approach-avoidance conflict decision test. In a lottery, participants can decide on their desired probability of a neutral outcome (depicted by sun) and of a reward (red bar) coupled with an aversive sensory experience (depicted by rain). D Approach-avoidance conflict ‘scoop & run’ test. Participants move an avatar (green triangle) outside a safe place and back to collect a financial reward token (yellow rhombus), under threat of being caught by a virtual predator (grey circle) and losing tokens. E Approach-avoidance conflict ‘stay & play’ test. Participant move an avatar (green triangle) on a 24 × 16 grid to collect multiple to financial reward tokens (yellow rhombi), under threat of being caught by a virtual predator (grey circle) and losing all tokens. F NPU test. In a predictable condition, aversive outcomes are always cued, whereas they appear at random in an unpredictable condition. In a neutral condition, no aversive outcomes occur. The social intrusion test (no illustration) quantifies children’s behavioural inhibition in social contexts. A is reproduced from ref. [76]. B was created by Hazaña17 (https://commons.wikimedia.org/w/index.php?curid=16311903) under CC BY-SA 3.0. C is provided by courtesy of Dr Robin Aupperle. D–F are the author’s own work.