Figure 1.

Experimental design. A, Learning (for details, see B) was framed by OVBs inside the scanner to measure emerging neural representations (for details, see C). A final 3D recall test probed memory across feature dimensions (for details, see D). B, Between OVBs, the following four learning tasks were completed (order: left to right): (1) participants learned six associations between objects and three-dimensional stimuli via encoding and test blocks, and (2) freely recalled them by reconstructing the 3D stimulus associated with a given object until correct; (3) subsequently, they acquired the concept of two stimulus categories via feedback-based categorization along the diagonal in two-dimensional concept space; and (4) navigating concept space required the 2D reconstruction (third dimension randomized) of an object-associated stimulus of a certain category. C, In the OVBs, the six objects plus an additional catch object were presented pseudorandomly with a stimulus duration of 1 s and interstimulus intervals of 3.5, 5, and 6.5 s while participants performed a catch object detection task. D, During postexperimental assessment of memory across feature dimensions, participants had to reconstruct the 3D stimulus associated with a given object and confirm their choice.