Effect of stimulus and response separation in a matching-to-sample task in the brushtail possum (Trichosurus vulpecula).

This study seeks to investigate the impact of changing the proximity of stimulus and response manipulanda on matching-to-sample performance in possums. Possums were presented with five rows of blue and yellow stimuli arranged vertically 25mm apart above response levers. Generally, peak performance occurred at the distance from the lever currently being trained. Performance generalized to distances close to the currently trained distance and decreased in accuracy at distances further from the trained level. The findings from this experiment provide evidence for placing stimuli and response manipulanda close together to improve acquisition of a task, and increase the responding accuracy in MTS experiments. This suggests that spatial contiguity in the relative location of stimuli and response manipulanda is critical to animals performing complex operant tasks.