Ecological validity (perception)

ecological validity as a type of experimental validity

This entry will describe the proper narrow and technical meaning of "ecological validity" as proposed by Egon Brunswik as part of the Brunswik Lens Model, the relation of "ecological validity" in "representative design" of research, and will outline the common misuses of the "ecological validity." For a more detailed explanation, see Hammond (1998).

Egon Brunswik defined the term "ecological validity" in the 1940s to describe a cue's informativeness. The ecological validity of a sensory cue in perception is the regression weight the cue X (something an organism might be able to measure from the proximal stimulus) in predicting a property of the world Y (some aspect of the distal stimulus). The "ecological validity" of X1 is its multiple regression weight when Y is regressed on X1, X2, and X3. For example, the color of a banana is a cue that indicates whether the banana is ripe. This particular cue has high ecological validity because a banana's ripeness is highly correlated with its color. By contrast, the presence of a sticker on the banana is a cue with an ecological validity close to 0, if (as seems likely) ripe and unripe bananas (in a fruit bowl, say) are equally likely to have stickers on them. The concept of ecological validity is closely related to likelihood in Bayesian statistical inference and to cue validity in statistics.

Brunswik's students have written that the now common use of "ecological validity" to describe a type of experimental validity was a corruption of his original terminology (see external link to paper by Hammond). Social scientists routinely refer to the "ecological validity" of an experiment as a rough synonym to Aronson and Carlsmith's (1968) concept of the "mundane realism" of the experimental procedures—Mundane realism refers to the extent to which the experimental situation is similar to situations people are likely to encounter outside of the laboratory. See Hammond's (1998) detailed critique of this mis use. Another common misuse of ecological validity is as a synonym for External Validity.

Kenneth R. Hammond "Ecological validity: Then and now."