Taya Shuichiro, Pasqualotto Achille
Hiyoshi Psychology Laboratory, Keio University, Japan.
Institute of Human Sciences, University of Tsukuba, Japan.
Iperception. 2025 Feb 27;16(1):20416695251319270. doi: 10.1177/20416695251319270. eCollection 2025 Jan-Feb.
When a photograph of the back of a hand with the fingers extended to the depth is observed upside-down, the hand appears vertically squashed, with extremely short fingers. The first aim of this study was to quantitatively measure the "frog hand illusion (FHI)", named after its bizarre appearance, and the second aim was to examine whether the dominant hand affects the strength of FHI. We measured the apparent shortening of the fingers using the method of constant stimuli. The results showed that the fingers of the inverted hand appeared to be shorter than those of the upright hand by about 5% on average. No effect of the dominant hand was observed. We propose the hypothesis that FHI occurs because of the attenuation of perceptual constancy, which might stem from observing the hand image from an atypical viewpoint.
当一张手指伸展到最大限度的手背照片倒置观察时，手看起来像是被垂直压扁了，手指极短。本研究的首要目的是定量测量以其怪异外观命名的“蛙手错觉（FHI）”，第二个目的是检验优势手是否会影响FHI的强度。我们使用恒定刺激法测量了手指的明显缩短情况。结果显示，倒置手的手指看起来比正立手的手指平均短约5%。未观察到优势手的影响。我们提出这样一个假设，即FHI的出现是由于知觉恒常性的减弱，这可能源于从非典型视角观察手部图像。
