highly significantp < 0.001
Crucially, however, when adding the dummy variable (with D = 1 if the observation was a response to a non-symbolic stimulus, and D = 0 if it was a response to a symbolic stimulus) the weight of the dummy x logarithmic interaction was highly significant ( B D x log = 0.029, st. error = 0.006, t ratio = 4.727, df = 22, p < 0.001), confirming that significant differences in logarithmic compression do exist between fast responses to non-symbolic and symbolic stimuli.