Effects of fixed- and variable-time schedules of mirror presentations on the swimming behaviour of Betta splendens

Abstract

The effects of response-independent mirror presentation schedules on the swimming behaviour of Betta splendens were studied in two experiments. In experiment 1, four fish received alternating baseline (no mirror) and fixed-time (FT) 2-min or variable-time (VT) 2-min mirror presentation conditions. Two fish consistently showed increased rates of mirror-side lap-swimming (MSLS; a back-and-forth swimming pattern) and decreased distance from the mirror during the inter-stimulus intervals (ISIs) of FT and VT sessions, and during baseline sessions that followed FT and VT phases. Data from one fish indicated that a VT schedule might increase both proximity to the mirror and MSLS rates that have decreased on FT. Therefore, in experiment 2 three fish from experiment 1 received alternating FT and VT conditions. Proximity to the mirror and MSLS rates increased during VT phases relative to FT phases in two fish, though effects were small and did not occur across all alternations. Additional findings were that MSLS during ISIs tended to increase within FT phases, that MSLS generally occurred either at a steady rate within ISIs or showed a scalloped effect, that mirror presentations produced approach to the mirror side that persisted during ISIs and subsequent baseline phases, and that mirror-side distance during the mirror presentations was less than during the ISIs. Although the findings were not consistent across all fish, they were replicated a number of times within at least two of the fish. The findings are discussed in terms of adventitious operant conditioning, respondent conditioning, and the behaviour systems approach. The results of this study increase the generality of response-independent schedule effects on locomotive behaviour.