Behavioral illusions: The Snark is a Boojum

A behavioral illusion is a regularity of behavior that appears to reflect something about the functional characteristics of an organism when it does not. This illusion occurs when the methods appropriate to the study of an open-loop or zero feedback (Z)-system are used to study the behavior of what is, in fact, a closed-loop or negative feedback (N)-system. The situation is like the one described in Lewis Carroll’s The Hunting of the Snark, where the sought-after Snark—analogous to the actual organism function—looks just like the feared Boojum—analogous to the illusory one. This article describes examples of three different kinds of behavioral illusion and explains how researchers can avoid the mistake of taking a Boojum for a Snark by reorienting the study of behavior toward identifying the perceptual variables that organisms control and away from seeking regularities in their overt behavior.