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Domestic cats treat the Kanizsa contour illusion as they do real square contours by spontaneously sitting or standing inside. [“If I fits, I sits”—is this the real reason cats love to sit down on your book or magazine when you’re trying to read‽ But why do they like to lay or sleep in squares in the first place? It is presumably evolved from their desert ancestor, but for what? Finding shade to sleep in during the hot day? Protection in mini-caves? (“Her birthing den is a sheltered place like dense grass, a burrow or hollow tree…”)]
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Using cats’ natural behaviors is effective for the study of cat behavior and cognition.
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The citizen science paradigm is successful at conducting ecologically valid research into the cognition of domestic cats.
A well-known phenomenon to cat owners is the tendency of their cats to sit in enclosed spaces such as boxes, laundry baskets, and even shape outlines taped on the floor. This investigative study asks whether domestic cats (Felis silvestris catus) are also susceptible to sitting in enclosures that are illusory in nature, using cats’ attraction to box-like spaces to assess their perception of the Kanizsa square visual illusion.
Carried out during the COVID-19 pandemic, this study randomly assigned citizen science participants Booklets of 6 randomized, counterbalanced daily stimuli to print out, prepare, and place on the floor in pairs. Owners observed and video-recorded their cats’ behavior with the stimuli and reported findings from home over the course of the 6 daily trials. This study ultimately reached over 500 pet cats and cat owners, and of those, 30 completed all the study’s trials. Of these, 9 cat subjects selected at least one stimulus by sitting within the contours (illusory or otherwise) with all limbs for at least 3 seconds. This study revealed that cats selected the Kanizsa illusion just as often as the square and more often than the control, indicating that domestic cats may treat the subjective Kanizsa contours as they do real contours. Given the drawbacks of citizen science projects such as participant attrition, future research would benefit from replicating this study in controlled settings.
To the best of our knowledge, this investigation is the first of its kind in 3 regards: a citizen science study of cat cognition; a formal examination into cats’ attraction to 2D rather than 3D enclosures; and study into cats’ susceptibility to illusory contours in an ecologically relevant paradigm. This study demonstrates the potential of more ecologically valid study of pet cats, and more broadly provides an interesting new perspective into cat visual perception research.
[Keywords: cat, behavior, vision, cognition, Kanizsa illusion]
…Previous research reveals that cats are, indeed, susceptible to certain visual illusions. De et al 1990 found that domestic cats could discriminate illusory contour orientation via contour-inducing semicircles. In 2019, Szenczi et al revealed that cats are susceptible to the size distorting Delboeuf illusion. Further, 2 studies found that both lions (Panthera leo) ( et al 2019) and domestic cats ( et al 2014) are susceptible to the Rotating Snake illusion, comprising a “moving” image caused by peripheral drift eliciting hunting-related behavior.
Perhaps most relevant, a study by et al 1988 examined domestic cats’ susceptibility to subjective contours via operant response to the Kanizsa square illusion. 2 young, female cats were trained to indicate where they viewed a subjective contour on an array of sectored disks in various orientations. The researchers controlled for other potential cues like luminance, temporal changes, and local patterns by introducing and modifying variables like motion and duration of stimuli exposure. They found that the cats demonstrated susceptibility to the Kanizsa illusion, indicating that cats likely perceive subjective contours as humans do (see Table 1 for a summary for illusion studies in cat species)…The present study supplements the results of et al 1988’s experiment with the addition of an increased sample size and a more inclusive sex and age range, in pet, rather than laboratory, cats. Moreover, rather than using standard operant conditioning procedures, the current study uses a more ecologically valid, real-world setting in which to evaluate spontaneous behavior. As cats transferred to novel environments can exhibit stress-related behaviors and thus not behave naturally ( et al 2015), this study also offers an at-home environment to explore domestic cats’ susceptibility to Kanizsa square contours in a natural setting.
