(A) Stimuli used in the behavioral and the fMRI experiment, depicting static images of 28 everyday actions. To increase perceptual variability, actions were shown from different viewpoints, in different scenes, using two different actors (see text for details) and different objects (for actions involving an object). For a full set of stimuli used in the fMRI experiment, see Figure 1—figure supplement 1. (B) Illustration of the behavioral experiment used for inverse multidimensional scaling. In the first trial of the experiment, participants were presented with an array of images arranged on the circumference of a gray circle (left panel). In each subsequent trial, an adaptive algorithm determined a subset of actions that provided optimal evidence for the pairwise dissimilarity estimates (see Kriegeskorte and Mur, 2012 and Materials and methods, for details). In different parts of the experiment, participants were asked to rearrange the images according to their perceived similarity with respect to a specific aspect of the action, namely, their meaning (or semantics), the body part(s) involved, the scene/context in which the action typically takes place, movement kinematics, and objects involved in the action. Right panel: Example arrangement resulting from the semantic task of one representative participant. Using inverse multidimensional scaling, we derived a behavioral model (see Figure 2) from this arrangement, individually for each participant, that we then used for the representational similarity analysis to individuate those brain regions that showed a similar representational geometry (for details, see Materials and methods section).