Lateralization has been observed across the animal kingdom. In mammals, this is often associated with complex or precise motor tasks, such as paw and hand use. A recent study reported that cats prefer a leftward (clockwise) sleeping position, suggestive of lateralization. However, limitations in the design and execution of that work raise questions about this finding. The aim of the present study was to further investigate this effect and establish if there is a lateralized preference in the sleeping position of domestic cats. Three activities were performed (1) assessment of YouTube videos of unique cats' sleeping positions; (2) assessment of images from Reddit of unique cats' sleeping positions and (3) assessment of images from Instagram to quantify the leftwards: rightwards preference of specific cats. Compared to a 50:50 ratio, no significant difference was found in lying position from videos (χ2 = 0.074, p = 0.786), images of unique cats (χ² = 0.522, p = 0.470) or from cats with multiple images (t = 0.836, p = 0.407). Given the full range of evidence available, it cannot be concluded that there is any population bias, preference or lateralization in the sleeping position of domestic cats. Results to the contrary can be explained by methodological issues.
Andrew Cooke (Tue,) studied this question.