To study the effects of early experience on conditioning, an experimenter raised four groups of rats in the presence of (1) no special stimuli, (2) a tone stimulus, (3) a vibratory stimulus, and (4) both a tone and a vibratory stimulus. The rats were later classically conditioned using either a tone or a vibratory stimulus as the conditioned stimulus and one of three levels of foot shock as the unconditioned stimulus. This is a 4 3 2 3 3 factorial design. The cell means, rather than the raw data, follow. The SStotal 5 41,151.00 and 5 5. The dependent variable was the number of trials to a predetermined criterion.