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Fig. 7.6. Tilt aftereffect over time in humans and in LISSOM. Each curve in (a) shows the average TAE of the LISSOM model with a different amount of adaptation. The TAE has the same S-shape throughout, and its magnitude increases monotonically. Similar comprehensive data are not available on humans, but a vertical slice corresponding to the peak in this graph has been measured, as is shown in (b): The thin lines depict the direct TAE for 12^o orientation difference vs. adaptation time for two human subjects SM and MWG, averaged over five trials (Greenlee and Magnussen 1987). For comparison, the thick line shows the corresponding TAE for the LISSOM model, averaged over nine trials. The adaptation time in LISSOM is measured in iterations, scaled to match the human plots as well as possible. The direct TAE increases approximately logarithmically in both LISSOM and humans; however, it does not saturate in LISSOM like it does in humans, suggesting that human adaptation faces additional limitations for long adaptation times. Reprinted from Bednar and Miikkulainen (2000b).