Many artworks challenge our perceptual habits and predictions and offer a plurality of potential meanings. However, a conceptualization of such “semantic instability” (SeIns; Muth & Carbon, 2016) and its specifics is vague so far. We recently presented an extended and systematized view on the concept integrating psychological and art-theoretical accounts. In order to structure the perceptual and cognitive phenomena associated with SeIns in art, we have now conducted an initial classification study and collected reports of experiences regarding a range of 17 artworks from the 20th and 21st centuries reflecting a variety of SeIns concepts. We revealed 4 clusters of SeIns via a k-means analysis: (a) integrative blend, (b) multistability, (c) indeterminacy, and (d) contrast to perceptual habits. This seminal classification aims at providing the basis for a new and more systematic view on SeIns in art.