Long-term adaptation effects of highly familiar faces are modulated by adaptation duration.

Adaptation to manipulated versions of face images can induce strong adaptation effects in face perception and the adjustment of memory representations has been suggested to underlie this effect. In previous studies such effects have been observed after short as well as long delays between adaptation and test (5 min and 24 h) and they were evident in face images identical to the adapting stimuli as well as in new images of the same individual and in faces that were not shown during adaptation (factor transferability). By using regression analysis, here we show that adaptation duration modulates the size of the adaptation effect, which was evident after both short and long time delays and across all levels of transferability tested.