was in fact spatial information that they were encoding, the researchers also presented lists in alphabetical order and semantic categories. However, the researchers found that it was in fact spatial information that the experts were chunking, allowing them to surpass the limitations of both visuo-spatial STM and WM. Animal research Certain species of paridae and corvidae (such as the black-capped chickadee and the scrub jay) are able to use spatial memory to remember where, when and what type of food they have cached. Studies on rats and squirrels have also suggested that they are able to use spatial memory to locate previously hidden food. Experiments using the radial maze have allowed researchers to control for a number of variables, such as the type of food hidden, the locations where the food is hidden, the retention interval, as well as any odor cues that could skew results of memory research. Studies have indicated that rats have memory for where they have hidden food and what type of food they have hidden. This is shown in retrieval behavior, such that the rats are selective in going more often to the arms of the maze where they have previously hidden preferred food than to arms with less preferred food or where no food was hidden. The evidence for the spatial memory of some species of animals, such as rats, indicates that they do use spatial memory to locate and retrieve hidden food stores. A study using GPS tracking to see where domestic cats go when their owners let them outside reported that cats have substantial spatial memory. Some of the cats in the study demonstrated exceptional long term spatial memory. One of them, usually traveling no further than to from its home, unexpectedly traveled some from its home. Researchers initially thought this to be a GPS malfunction, but soon discovered that the cat's owners went out of town that weekend, and that the house the cat went to was the owner's old house. The owners and the cat had not lived in that house for well over a year. Visual–spatial distinction Logie (1995) proposed that the visuo-spatial sketchpad is broken down into two subcomponents, one visual and one spatial. These are the visual cache and the inner scribe, respectively. The visual cache is a temporary visual store including such dimensions as color and shape. Conversely, the inner scribe is a rehearsal mechanism for