Human analog tests of the sixth stage of object permanence

Two adult cats were tested on multiple invisible displacement. A dowel was established as a secondary reinforcer and hidden in a manner similar to that used to assess the culmination of sensorimotor intelligence in human infants. Three other cats were tested on single invisible displacement, a simpler version of the task. For human infants, this task is used to assess the beginning of mental representation in the sixth and last stage of sensorimotor intelligence. The cats' searches on these tasks were consistent with representation of an unsensed object and fully developed sensorimotor intelligence.