Pattern biases, but not positional cues, influence learning in the little brown skink, Scincella lateralis

Abstract

Abstract Studies of many lizard species have established they are capable of learning to escape to one specific retreat out of several available retreats and will escape to it when subjected to a simulated predator attack. Recently, researchers have focused on the processes involved in learning, including what cues lizards use to learn to escape to a retreat. Previous work on the little brown skink lizard, Scincella lateralis, has shown that it is capable of learning to escape to a specific retreat when it has gained prior experience with its environment and that its performance is better when a retreat is associated with a vertical stripe local cue than when the retreat was associated with a horizontal stripe one. Here I report the results of two additional experiments undertaken to gain a better understanding of how little brown skinks react to cues in their environment. In Experiment 1, the positional cue test, I tested if little brown skinks could be trained to escape to a specific retreat when the only cue available was a positional cue that lizards could use to orient themselves by conducting a series of trials in which little brown skinks were trained to escape to the retreat to the left or the right of a vertical cylinder. Only 2 of the 16 (12.5%) little brown skinks met the learning criterion. This was not significantly different from what is expected if lizards chose their retreats at random suggesting little brown skinks are poor at learning when only a positional cue is available. In Experiment 2, the pattern bias test, I tested if the little brown skink’s superior performance learning to escape to a retreat with a vertical stripe cue in previous experiments was due to a bias for vertical stripes (or against horizontal stripes) through a series of trials in which little brown skinks had to choose between two escape retreats: one with a vertical stripe local cue and the other with a horizontal stripe local cue. A significant bias for the vertical stripe local cue retreat was found among 24 adults, but not among 12 neonates. These results suggest pattern bias among adult little brown skinks impacted the results of previous studies. The possibility that lizards may have biases for colours or shapes and that these biases may have an impact on learning studies is discussed.