Some researchers argue that holistic processing is unique to face recognition supported by the face inversion effect. However, findings such as the body inversion effect challenge the face processing-specificity hypothesis, thus supporting the expertise hypothesis. Few studies have explored a possible hand inversion effect which could involve special processing similar to the face and body. We conducted four experiments to investigate the time course and flexibility of the hand posture inversion effect. We utilized a same/different discrimination task (Experiments 1 and 2), an identification task (Experiment 3), and a training paradigm involving the exposure of different hand orientations (Experiment 4). The results show the hand posture inversion effect (with fingers up as upright orientation) was not initially observed during the early phase of testing, but occurred in later phases. This suggests that both lifetime experience and recent exposure affect the hand posture inversion effect. We also found the hand posture inversion effect, once established, was stable across days and remained consistent across different tasks. In addition, the hand posture inversion effect for specific orientations could be obtained with short-term training of a given orientation, indicating the cognitive process is flexible.

一些研究人员认为，整体处理是人脸反转效应支持的人脸识别所独有的。然而，身体倒置效应等发现挑战了面部处理特异性假说，从而支持了专业知识假说。很少有研究探索可能涉及类似于面部和身体的特殊处理的手部倒置效应。我们进行了四个实验来研究手部姿势反转效应的时间过程和灵活性。我们使用了相同/不同的辨别任务（实验 1 和 2）、识别任务（实验 3）和涉及暴露不同手部方向的训练范式（实验 4）。结果表明，在测试的早期阶段最初没有观察到手部姿势反转效应（手指向上为直立方向），但在后期阶段出现。这表明，一生的经历和最近的接触都会影响手部姿势倒置效应。我们还发现，手部姿势倒置效应一旦建立，就会在几天内保持稳定，并且在不同任务中保持一致。此外，特定方向的手部姿势倒置效果可以通过给定方向的短期训练获得，表明认知过程是灵活的。在几天内保持稳定，并且在不同任务中保持一致。此外，特定方向的手部姿势倒置效果可以通过给定方向的短期训练获得，表明认知过程是灵活的。在几天内保持稳定，并且在不同任务中保持一致。此外，特定方向的手部姿势倒置效果可以通过给定方向的短期训练获得，表明认知过程是灵活的。