Data and supplementary materials for Object permanence in domestic cats (Felis catus) using violation-of-expectancy by owner and stranger

Version 2 - 11th September 2025:We had mistakenly uploaded the same video in the 'Forman2025_PLOSONE_supplementaryvideos' folder. The video for 'Supplementary Video 1 single visible displacement' and 'Supplementary Video 3 violation event' were identical. The correct exemplar video has now been uploaded for 'Supplementary Video 1 single visible displacement'.Data and supplementary materials for paper published in PLoS One July 2025One folder, 'reliabilitystats', provides: two datasets (one for ICC tests and one for Cohen's kappa tests); and an R markdown file that shows our code. These resources were used for carrying out and interpreting the reliability statistics. Please note that R/RStudio is required to open .rmd files.One folder, 'inferentialstats', provides: the experimental dataset; an R markdown file that shows our code and generated our plots; the knitted markdown Word Document; and a Word Document that outlines the final models we interpreted in the manuscript. These resources were used for carrying out and interpreting descriptive and inferential statistics. Please note that R/RStudio is required to open .rmd files.One folder, 'supplementaryvideos', provides supplementary example videos for each of the three trial types (single visible displacement; consistent event; violation event) performed by either the owner or the researcher.Article abstractObject permanence, the understanding that objects continue to exist while out of sight, has been extensively researched in human infants and animals. Cats have been shown to reach Stage 5 object permanence by passing successive visible displacement tests, but their understanding of Stage 6 object permanence is less clear. We tested 18 domestic cats on their understanding of Stage 4 (single visible displacement; SVD) and Stage 6 (invisible displacement; IVD) of object permanence in their home environment. Additionally, we investigated how person familiarity may influence study engagement. In SVD tests, the box manipulator (owner or researcher) hid a toy in one of two cardboard boxes for the cat to find. In IVD tests, we implemented a violation-of-expectancy procedure in which the box manipulator showed a toy re-appearing out of either a) the same box it was hidden in (consistent trials) or b) the box it was not hidden in (violation trials). Approximately half of the cats (56%) did not find the hidden toy in SVD trials, with 42% of these cats not attempting to find the toy, despite previous research demonstrating that cats can retrieve hidden objects in successive SVD tests. No predictors significantly influenced whether cats found the toy, or which box was checked first (toy or empty box). In IVD trials, we unexpectedly found that cats were more likely to play with the toy and display more toy box-directed behaviours in consistent trials than violation trials. Similarly, we found that cats were more likely to display toy and empty box-directed behaviours in trials where the researcher acted as the box manipulator. Other factors such as breed, outdoor access, cat sex and the first person to act as the box manipulator also influenced toy-directed behaviours. We discuss the complexity of person familiarity in research contexts and highlight some methodological challenges in studying cat cognition.