Visual Discrimination Learning in the Small Octopus O ctopus ocellatus

Abstract Octopus ocellatus is a small benthic species of octopus that is easy to rear and spawns large eggs during a short life cycle. These and other features of O . ocellatus may make it an advantageous subject for a broad range of behavioral studies, including those involving various types of learning. However, no type of learning has been studied in O . ocellatus . In a successive visual discrimination task, in which a ‘positive’ or ‘negative’ stimulus (white or black rectangle) was presented to a subject octopus and appropriate rewards or punishments were given to the subject, the rate of ‘correct’ responses (i.e., touches to the positive stimulus or refraining from the negative stimulus) gradually increased. Moreover, ‘observer’ octopuses that observed another octopus performing a visual discrimination task in which reward was also given to the ‘incorrect’ responses (touches to the negative stimulus) showed a higher ratio of incorrect responses in their test sessions. These results, coupled with the physical characteristics of O . ocellatus , indicate that this species is potentially suitable for neurogenetic and neuroembryological studies of learning.