Three-fold cubes: An object whose form can be interpreted in three different ways

Modern brain imaging techniques are allowing scientists to peer into the workings of the brain as never before. Such studies require visual stimuli whose impact on brain activity can be tracked amongst the hubbub of other thoughts. Ambiguous figures are important in this regard because although the stimulus does not change, the viewer’s mental image does; providing a stimulus-independent link to conscious experience. Although ambiguous figures generally offer two interpretations, they can offer more. Stimuli producing three interpretations are rare, but of especial interest because they provide a more exacting test of what is happening in our brains when perceptions switch.