Extended Data Fig. 4. Metamers from a classic vision model.

a, Schematic of HMAX vision model. The HMAX vision model is a biologically-motivated architecture with cascaded filtering and pooling operations inspired by simple and complex cells in the primate visual system and was intended to capture aspects of biological object recognition^3,8. We generated model metamers by matching all units at the S1, C1, S2, or C2 stage of the model. b, Example HMAX model metamers. c, Although HMAX is substantially shallower than the “deep” neural network models investigated in the rest of this paper, it is evident that by the C2 model stage its model metamers are comparably unrecognizable to humans (significant main effect of model stage, F(4,76) = 351.9, p < 0.0001, ${\eta }_p^2=0.95$). This classical model thus also has invariances that differ from those of the human object recognition system. Error bars plot s.e.m. across participants (N = 20). HMAX metamers were black and white, while all metamers from all other models were in color.