Visual adaptation is a universal phenomenon associated with human visual system. This adaptation affects not only the perception of low-level visual systems processing color, motion, and orientation, but also the perception of high-level visual systems processing complex visual patterns, such as facial identity and expression. Although it remains unclear for the mutual interaction mechanism between systems at different levels, this issue is the key to understand the hierarchical neural coding and computation mechanism. Thus, we examined whether the low-level adaptation influences on the high-level aftereffect by means of cross-level adaptation paradigm (i.e. color, figure adaptation versus facial identity adaptation). We measured the identity aftereffects within the real face test images on real face, color chip and figure adapting conditions. The cross-level mutual influence was evaluated by the aftereffect size among different adapting conditions. The results suggest that the adaptation to color and figure contributes to the high-level facial identity aftereffect. Besides, the real face adaptation obtained the significantly stronger aftereffect than the color chip or the figure adaptation. Our results reveal the possibility of cross-level adaptation propagation and implicitly indicate a high-level holistic facial neural representation. Based on these results, we discussed the theoretical implication of cross-level adaptation propagation for understanding the hierarchical sensory neural systems.

Fitts' law has been applied in many studies to evaluate pointing tasks. However, the quantitative effect of using color in the interfaces has not been discussed in the literature. This paper introduces research on the effects of color in pointing tasks using Fitts' law as the evaluation method. Different colors and color presentation styles are applied in the experiments which are similar in design to the paradigmatic Fitts' law pointing task. The experimental results show that when the subjects use a mouse as the input device, there is no significant difference between an interface with a colored target and one with a white target in the mean performance time. The results also reveal that color presentation styles will offer no significant difference to pointing tasks when the mouse is applied. However, when the interface of tablet PC and pen was applied, subjects without much experience in tablet personal computer usage needed more time to perform the task with colored targets than with a white target. Furthermore, when the colors are changed randomly during the selection process, the difference is even more obvious. These results are confirmed by a Checking Experiment and a Learning Effect Experiment which we performed on different groups of subjects.