Stratified analyses reveal temporal instability and seasonal modulation of lateralized lying in domestic cats

Behavioral lateralization is often described as a stable trait expressed at either the population or individual level. However, such conclusions are frequently drawn from limited or uneven observations, raising questions about how lateralization should be interpreted under naturalistic conditions. Here, I investigated lateralized lying behavior in domestic cats using a large, citizen-science dataset characterized by highly variable observation frequencies. To address this heterogeneity, I applied a stratified analytical framework separating population-level, individual-level, and time-resolved analyses. Across low-frequency observations involving many individuals with sparse sampling, I found no evidence for a strong population-level lateral bias in lying posture. In contrast, cats with moderate observation frequencies exhibited pronounced inter-individual variability, with clear lateral preferences expressed in both directions but no uniform group-level orientation. Even among high-frequency individuals with extensive longitudinal records, overall lateralization indices remained modest when aggregated across time. However, fine-grained analyses across solar terms revealed substantial within-individual fluctuations, including directional reversals, indicating that lateralized lying behavior is dynamic rather than fixed. These temporal trajectories differed across individuals and were attenuated in an air-conditioned environment, consistent with context-dependent modulation. Together, my results suggest that lateralized lying in domestic cats is best understood as an individual-specific and environmentally modulated behavior, rather than a stable population-wide trait. By explicitly aligning analytical scale with data resolution, this study highlights the importance of longitudinal and context-aware approaches for interpreting behavioral lateralization under naturalistic conditions.