A remarkable John O’Brien cartoon in the 2/3/25 New Yorker, in which a cowboy whips his lariat in pursuit of a cow, with a stark desert landscape of mesas and buttes outlined behind them:
(#1) But wait! That line in the cartoon is both the lariat — the figure — and the outline of the landscape — the (back)ground — so that looking at the cartoon, you perceive the one, then the other, shifting from one to another: what is figure, what s ground?
It’s a percept-shifting visual illusion, exploiting an ambiguous image, in particular a figure-ground ambiguity. Here done as a joke in a cartoon, a visual parallel to what I’ve called sense-shifting pun jokes.
Background 1. Ambiguous visual images. From my 8/5/21 posting “The mirror of the manatee”:
from the Illusions Index site on “All Is Vanity”:
(#2) Woman gazing in a mirror, or skull?Basic information from the site: The All Is Vanity Ambiguous Figure was created by the American illustrator Charles Allan Gilbert (1873 – 1929) in 1892. The figure can be seen as a woman looking at her reflection in a mirror, or a skull (Oliva, 2013). [It] belongs in a large class of illusions where a two-dimensional figure, or three-dimensional object can be seen in two or more sharply distinct ways
And your perception flips back and forth from one to another.
Background 2. From my 12/2/23 posting “Sense-shifting pun jokes”:
A common joke form exploits an ambiguous expression E. Prior likelihood or the preceding context in the joke favors one understanding for E, but then fresh context (in the joke) brings out another, more surprising one. The effect is that the sense of E has shifted as the joke proceeds. It’s a pun, son. Used in a sense-shifting pun joke. (Puns get used in all sorts of jokes: knock-knock jokes, one type of riddle joke, and more.)
[with the example]
I threw a ball for my dog.
… Extravagant, I know.
But he looks amazing in a tuxedo.Compare this shift with what happens to many people when they’re confronted with [an optical illusion, like] the Goblet Illusion:
(#3)
Because of several perceptual predispositions, we’re inclined to see [this image] at first as a white goblet against a black background, but we can then be nudged to shift our interpretation of what we’re seeing to the outlines of two black faces against a white background. And after that we go back and forth between the two understandings.
Summing up: sense-shifting pun jokes, exploiting ambiguous verbal expressions; and percept-shifting visual illusions, exploiting ambiguous images, in particular figure-ground ambiguities. It’s this — no, it’s that.