Spatial serial conditioning maintained with minimal temporal contingency

Abstract

Two experiments used a spatial serial conditioning paradigm to assess the effectiveness of spatially informative conditioned stimuli in eliciting tracking behavior in pigeons. The experimental paradigm consisted of the simultaneous presentation of 2 key lights (CS2 and CTRL), followed by another key light (CS1), followed by food (the unconditioned stimulus or US). CS2 and CTRL were presented in 2 of 3 possible locations, randomly assigned; CS1 was always presented in the same location as CS2. CS2 was designed to signal the spatial, but not the temporal locus of CS1; CS1 signaled the temporal locus of the US. In experiment 1, differential pecking on CS2 was observed even when CS2 was present throughout the interval between consecutive presentations of CS1, but only in a minority of pigeons; prevalence of differential pecking was enhanced when CS2 duration was halved. A control condition verified that pecking on CS2 was not due to temporal proximity between CS2 and US. Experiment 2 demonstrated the reversibility of spatial conditioning between CS2 and CTRL. Asymptotic performance never involved tracking CTRL more than CS2 for any of 16 pigeons. It is inferred that pigeons learned the spatial association between CS2 and CS1, and that temporal contingency facilitated its expression as tracking behavior.