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About this tool
Watch classic bistable figures flip between two interpretations and measure your own dominance durations.
An ambiguous figure is a single image with two mutually exclusive interpretations, and this viewer measures how long each one holds before your perception flips — the dominance duration used in psychophysics. Tap on every reversal you see in a Necker cube, Schröder stairs or Rubin's vase and it returns the mean, median, coefficient of variation and the gamma shape parameter k = mean² / variance. It is built for psychology students, teachers demonstrating bistable perception, and anyone curious how measurable their own perceptual switching is.
Open Ambiguous Figure Viewer on AltFTool — it loads instantly in your browser.
Find a figure in the gallery: type into Search optical illusions... or narrow the grid with the Category, Difficulty (Beginner, Intermediate, Advanced) and Status (Solved, Unsolved, Favorites) chip rows, watching the Showing X of Y figures counter. Click any card, or Open Featured Figure, to open it in the viewer.
Inside the viewer, use Select Interpretation to switch between the figure's readings — each one prints its own Perceptual Focus hint, such as Look for the beak pointing to the left for the duck. The Viewing Tools panel gives In, Out, Reset, Blur, Spotlight and Invert (also +, -, r, b, s and i on the keyboard), and Perception Metrics reports the live Zoom Level, Active Mode, Difficulty and number of Interpretations.
Mark Solved records the figure and the button switches to Solved!, the heart button adds it to Favorites, and both survive a reload because they are kept in this browser. Share copies the page link and flashes Link copied to clipboard!, Download Image saves the artwork as <figure-id>.svg, and Escape closes the viewer.
Reports dominance duration, coefficient of variation and gamma shape, not a personality-style score.
Two taps within 150 ms are refused, because perception cannot genuinely reverse that fast.
Timing and statistics happen in the browser; nothing about your trial is uploaded.
A drawing that supports two equally valid interpretations, only one of which you can see at a time. The Necker cube (Louis Albert Necker, 1832) is the classic case: with no shading or occlusion cues, either square can read as the near face, and perception alternates between them without your choosing.
Between about 1 and 5 seconds for a static ambiguous figure in an untrained observer, with the mean typically near 2-3 seconds. Durations shorten with continued viewing and lengthen if you deliberately hold one interpretation, though you cannot stop reversals entirely.
Because the durations are right-skewed: many short holds and a thin tail of long ones. Borsellino and colleagues reported in Kybernetik (1972) that reversal times fit a gamma distribution with a shape parameter of roughly 3 to 4, which corresponds to a coefficient of variation near 0.5.
Only partly. Fixating on a specific corner or edge biases which interpretation appears and can extend it, which is why this tool includes a hint option. Voluntary control changes the balance between the two percepts, but the alternation itself continues on its own.