1. the degree to which results obtained from research or experimentation are representative of conditions in the wider world. For example, psychological research carried out exclusively among university students might have a low ecological validity when applied to the population as a whole. Ecological validity may be threatened by experimenter bias, oversimplification of a real-world situation, or naive sampling strategies that produce an unrepresentative selection of participants. See also validity. [defined by Martin T. Orne on the basis of work by Egon Brunswik]

2. in perception, the degree to which a proximal stimulus (i.e., the stimulus as it impinges on the receptor) covaries with the distal stimulus (i.e., the actual stimulus in the physical environment). [originated by Egon Brunswik]