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Fig. 7.5. Tilt aftereffect in humans and in LISSOM. The LISSOM network adapted to a vertical (0^o) line at the center of the retina for 90 iterations, and the TAE was measured for test lines oriented at each angle. The thick line shows the average magnitude of the TAE over nine trials, as described in Section 7.2.2. Positive values of aftereffect denote a counterclockwise change in the perceived orientation of the test line. The graph is roughly anti-symmetric around 0^o, i.e. the TAE is essentially the same in both directions relative to the adaptation line. The error bars indicate ±1 SEM; in most cases they are too small to be visible because the TAE was highly consistent between different runs (Appendix B.2). For comparison, the thin line with circles represents the TAE, averaged over 10 trials, for the single human subject (DEM) with the most complete data in the Mitchell and Muir (1976) study. The LISSOM TAE curve closely resembles the human TAE curve, showing both direct and indirect tilt aftereffects. Reprinted from Bednar and Miikkulainen (2000b).