The Thinker is a bronze sculpture by Auguste Rodin, usually placed on a stone pedestal. The work shows a nude male figure of over life-size sitting on a rock with his chin resting on one hand as though deep in thought and is often used as an image to represent philosophy. There are about 28 full size castings, in which the figure is about 186cm high, though not all were made during Rodin's lifetime and under his supervision; as well as various other versions, several in plaster, studies, and posthumous castings exist in a range of sizes. Rodin first conceived the figure as part of his work The Gates of Hell commissioned in 1880, but the first of the familiar monumental bronze castings did not appear until 1904. 
While currently the statue shows a figure with his chin rested on his curled hand, many people remember the statue portraying the figure with a closed fist against his forehead. 
ResidueResidue for this Mandela Effect is primarily in the form of anecdotal reports of it's appearance, yet there are also many photographs showing people emulating the "forehead pose".
But the iconography of a person resting his/her chin on his/her hand while in the middle of great thought or psychological torment is not a new one. Michelangelo's allegorical sculpture Night (part of a sculptural pair - Night and Day - for the Tomb of Giuliano de' Medici). is perhaps the inspiration for The Thinker. Night, personified as a reclining woman, rests her forehead upon her hand in a pensive manner. She may be resisting the inevitable sleep that is about to come, or she, as Night, may be reflecting on the day that has come to a close. 
Nowadays, intellectuals are likely to be tormented by a public who mock their idle musings by copying the pretentious pose of deep thinking. Yet, strangely, the tormentors usually fail to copy the gesture correctly: placing the knuckles on their foreheads, not as Rodin did, against the chin. 
It is easily Rodin's most celebrated piece. This is a fine copy of the thinking man in his famed hunched pose with his fist on his forehead.
Rodin's thinker sits with his head bowed, forehead resting on his clenched fist.
I'd be depicted by my forehead / rested on my palm
One potential explanation that has been suggested is that people generally pay more attention to people emulating the pose rather than to the actual statue itself. The attention paid to people incorrectly copying the pose causes a sort of "loop" that causes more and more people to incorrectly assume the pose of the statue. 
- Wikipedia - The Thinker|https://en.wikipedia.org/wiki/The_Thinker
- One of the most famous statues... (reddit)|https://www.reddit.com/r/MandelaEffect/comments/55ceq4/one_of_the_most_famous_statues_rodins_the_thinker/
- La Nuit|http://mchistorical.tripod.com/id63.html
- He strikes a pose, but his thoughts elude us|https://www.timeshighereducation.com/news/he-strikes-a-pose-but-his-thoughts-elude-us/205685.article
- Wholesale sculptures|http://wholesalesculptures.com/thinker-small-by-auguste-rodin/