Muto, H., Ide, M., Tomita, A., & Morikawa, K. (武藤拓之・井手麻由・富田瑛智・森川和則)

Viewpoint invariance of eye size illusion caused by eyeshadow

Frontiers in Psychology, 10:1510

doi: 10.3389/fpsyg.2019.01510

Previous research found that application of eyeshadow on the upper eyelids induces overestimation of eye size. The present study examined whether or not this eyeshadow illusion is dependent on viewpoint. We created a three-dimensional model of a female face and manipulated the presence/absence of eyeshadow and face orientation around the axis of yaw (Experiment 1) or pitch (Experiment 2) rotation. Using the staircase method, we measured perceived eye size for each face stimulus. Results showed that the eyeshadow illusion occurred regardless of face orientation around axes of both yaw and pitch rotations. Crucially, the illusion’s magnitude did not vary across face orientations; lack of interaction between the illusion’s magnitude and face orientation was confirmed by small values of Bayes factors. These findings ruled out the hypothesis that eyeshadow serves as a depth cue and leads to overestimation of eye size due to size-distance scaling. Alternatively, the present findings suggest that the eyeshadow illusion can be well explained by the assimilation between the eyes and eyeshadow, which also facilitates assimilation between the eyes and eyebrows. Practical implications and the present findings’ generalizability are also discussed.

著者Contact先の email:
h.muto[at] (武藤拓之) ([at] を@に置き換えてください)

上瞼にアイシャドウを塗ると目の大きさが実際よりも大きく知覚される錯視のメカニズムに関する研究です。本研究は,アイシャドウが引き起こす目の過大視錯視が顔の向き(視点)によらずに同程度生じることを明らかにしました。この結果は,アイシャドウの陰影が奥行き手がかりとして機能し,目が遠くに位置するように知覚されるため目の過大視が生じるという説明 (size-distance scaling account) を棄却し,アイシャドウ(および眉)と目の同化によって目の過大視が生じるという説明 (assimilation account) を支持する結果であるといえます。(武藤)