What Is the Open Field Test?
The Open Field Test (OFT) was first described by Calvin Hall in 1934 as a measure of emotional reactivity in rats. Today it is one of the most commonly used assays in behavioral neuroscience, pharmacology, and toxicology. The apparatus is a simple enclosed arena — rectangular or circular — with opaque walls high enough to prevent escape. The animal is placed in the center or a corner and allowed to freely explore for a set duration (typically 5-30 minutes). A video camera mounted above the arena captures the animal's position over time. From the XY tracking data, researchers extract metrics including total distance traveled (locomotor activity), mean velocity, time spent in the center vs. periphery (anxiety index), number of center zone entries, and thigmotaxis index (wall-hugging). The OFT is valued for its simplicity, the absence of aversive stimuli beyond novelty itself, and its sensitivity to a wide range of pharmacological and genetic manipulations affecting locomotion, exploration, and anxiety.