Aversive control of Betta splendens behaviour using water disturbances: effects of signalled and unsignalled free-operant avoidance, escape, and punishment contingencies
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Research on aversive control of behaviour has dramatically declined over the past decades. This trend is primarily a consequence of an over-reliance on shock-based procedures, which have been increasingly criticized on ethical, practical, and ecological validity grounds. The continued study of aversive regulation thus requires the development of viable alternatives. Six preliminary experiments, triggered by serendipitous observations of Betta splendens’ reactions to unintended water disturbances, allowed for (a) developing a water flows (WFs) experimental paradigm; (b) confirming the aversive function of WFs; and (c) demonstrating the feasibility of the WFs paradigm as an alternative to the use of electric shock, as it does not involve painful stimulation and carries a higher level of inherent ecological validity. Based on the relevance of free-operant avoidance phenomena (Sidman, 1953a) for the study of aversive control, the fact that these have only been demonstrated in one fish species (goldfish) using shocks, and that the only attempt to show another form of avoidance in Betta splendens produced inconclusive results (Otis & Cerf, 1963), the WFs paradigm was implemented in two experiments aimed at addressing these issues. These studies were aligned with a research program on spatiotemporal analysis of behaviour that has demonstrated, over the course of several decades, that a comprehensive understanding of behavioural processes requires an approach that includes, but is not limited to, the study of rates of discrete responses (e.g., key pecks of a pigeon). Accordingly, a more holistic interpretation of experimental data than is typical for behavioural studies was attained through a combined analysis of the frequency and temporal distribution of a target response (crossings in a shuttle-tank), patterns of swimming trajectories, instances and durations of the aversive stimulus, and the occurrence of behaviour related to different features of the experimental tank. In Experiment 1, Betta splendens exposed to a free-operant avoidance procedure reliably escaped WFs but did not develop avoidance behaviour even though escape improved with practice. Moreover, adding a warning stimulus (curtains of air bubbles - CABs) to the free-operant procedure did not produce increments in avoidance behaviour, as has been demonstrated in other species. Considering these findings, Experiment 2 maintained the same free-operant avoidance contingencies, but escape responses were now scheduled to produce the WFs (punishment and extinction of escape). The result of this manipulation was not a substantial decrease of escape, but an initial large increase of this response, followed by a progressive decrease to approximately pre-punishment levels. In addition, punishment did not result in increased avoidance responding as an alternative response. The explanations for these unexpected findings relate to the duration of the CABs; sign- and goal-tracking effects; uncontrolled stimulation produced by water pump activation/operation; unintended reinforcement (mirror reflections and delay between the pump activation and WFs reaching full strength); and the development of responses that allowed the fish to reduce their exposure to high-intensity WFs (i.e., alternative behaviour). The need for investigating the effects of adjusting the WF procedures to the ecology and biology of Betta splendens is also discussed, particularly in regard to their territoriality and predominant defensive response (immobility) in relation to the experimental apparatuses and the target response (changing compartments).