Figure 1.

(A). A graphical depiction of how the neural response to different stimulus dimensions is measured via univariate voxel-wise analysis. The most common practice for testing whether the dimensions Size, Predacity, and Scariness are coded in the brain using voxel-wise analysis is to test whether the beta weights for the three dimensions are significantly different from zero in individual voxels or across an ROI. (B). A graphical depiction of one way in which MVPA may be used to examine whether a region of the brain codes for differences between the mammals. Activation patterns for test items are compared to those for a number of items using a similarity function. Here, the new pattern is classified as the mammal with highest similarity and the accuracy of this prediction is assessed. Accurate classification indicates that the activation patterns contain information about the differences between these mammals in some latent neural representational space. The question we address in the present paper is whether any conclusions can be reached about the content or dimensionality of this latent space using prediction accuracy or other basic similarity tests alone