Fig. 6.

The geometry of item typicality. For a semantic distinction $\alpha$ (in this case, $\alpha$ is the bird–fish distinction) the object-analyzer vector ${\mathbf{\text{v}}}_i^{\alpha }$ arranges objects $i$ along an internal neural-representation space, where the most typical birds take the extremal positive coordinates and the most typical fish take the extremal negative coordinates. Objects like a rose, that is neither a bird nor a fish, are located near the origin on this axis. Positions along the neural semantic axis can also be obtained by computing the inner product between the feature vector ${\mathbf{\text{o}}}^i$ for object $i$ and the feature synthesizer ${\mathbf{\text{u}}}^{\alpha }$ as in [13]. Moreover, ${\mathbf{\text{u}}}^{\alpha }$ can be thought of as a category prototype for semantic distinction $\alpha$ through [14].