title: Reconsideration of Serial Visual Reversal Learning in Octopus(Octopus vulgaris)from a Methodological Perspective.
abstract: Octopuses(Octopus vulgaris)are generally considered to possess extraordinary cognitive abilities including the ability to successfully perform in a serial reversal learning task. During reversal learning, an animal is presented with a discrimination problem and after reaching a learning criterion, the signs of the stimuli are reversed: the former positive becomes the negative stimulus and vice versa. If an animal improves its performance over reversals, it is ascribed advanced cognitive abilities. Reversal learning has been tested in octopus in a number of studies. However, the experimental procedures adopted in these studies involved pre-training on the new positive stimulus after a reversal, strong negative reinforcement or might have enabled secondary cueing by the experimenter. These procedures could have all affected the outcome of reversal learning. Thus, in this study, serial visual reversal learning was revisited in octopus. We trained four common octopuses (O. vulgaris) to discriminate between 2-dimensional stimuli presented on a monitor in a simultaneous visual discrimination task and reversed the signs of the stimuli each time the animals reached the learning criterion of ≥80% in two consecutive sessions. The animals were trained using operant conditioning techniques including a secondary reinforcer, a rod that was pushed up and down the feeding tube, which signaled the correctness of a response and preceded the subsequent primary reinforcement of food. The experimental protocol did not involve negative reinforcement. One animal completed four reversals and showed progressive improvement, i.e., it decreased its errors to criterion the more reversals it experienced. This animal developed a generalized response strategy. In contrast, another animal completed only one reversal, whereas two animals did not learn to reverse during the first reversal. In conclusion, some octopus individuals can learn to reverse in a visual task demonstrating behavioral flexibility even with a refined methodology.
authors.affiliation: Institute for Biosciences, Sensory and Cognitive Ecology, University of Rostock Rostock, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Bublitz
authors.affiliation: Institute for Biosciences, Sensory and Cognitive Ecology, University of Rostock Rostock, Germany.
authors.forename: Severine R
authors.initials: SR
authors.lastname: Weinhold
authors.affiliation: Institute for Biosciences, Sensory and Cognitive Ecology, University of Rostock Rostock, Germany.
authors.forename: Sophia
authors.initials: S
authors.lastname: Strobel
authors.affiliation: Institute for Biosciences, Sensory and Cognitive Ecology, University of Rostock Rostock, Germany.
authors.forename: Guido
authors.initials: G
authors.lastname: Dehnhardt
authors.affiliation: Institute for Biosciences, Sensory and Cognitive Ecology, University of Rostock Rostock, Germany.
authors.forename: Frederike D
authors.initials: FD
authors.lastname: Hanke
keywords: behavioral flexibility; operant conditioning; reversal learning; secondary reinforcer; simultaneous visual discrimination