Visual habituation in the common octopus (Octopus vulgaris)

Non-associative learning is one of the basic manifestations of behavioral flexibility. In order to document this behavioral trait in Octopus vulgaris, we tested the animal's habituation towards a repeatedly presented prey-like visual stimulus. A plastic model of a lobster was presented outside the tank for 15 times for 15 seconds at the beginning of each minute of the experimental session. Sessions were repeated 6 h and 24 h after initial presentation. Eight out of ten animals habituated to the stimulus they could only visually inspect during all experimental sessions. The animals showed significant short-term effect in habituation between the first session (0 h) and the second session (6 h). However, no clear long-term differences between the first session (0 h) and the third session (24 h) were present. Our finding that octopuses do show strong short-term habituation but no long-term habituation is consistent with earlier findings, but in our study we used a purely visual stimulus. This set-up enables us to apply the already established technique of extra-cellular recording from the octopus, central nervous system to monitor the activity of the MSF (median superior frontal lobe) and VL (vertical lobe) during non-associative learning.