The cardiac self-stimulation hypothesis and the chick's differential attraction toward intermittent sound

Two experiments were conducted to determine whether the chick's attraction toward specific rates of intermittent sound stems from long-term prehatch exposure by the chick to its own fetal heart beat. Contrary to prediction, Experiment I showed stronger attraction toward an intermittent square wave white noise signal matched for pulse rate, overall pulse duration, and mean intensity, than the sound of the actual fetal heart beat from which this attraction is said to derive, Experiment II demonstrated that long-term prehatch exposure to an intermittent auditory signal having a normally non-preferred rate will not establish an attraction for that same rate after hatching unless it contains a frequency component having latent appetitive properties. Alternatives to the cardiac self-stimulation hypothesis are discussed and, in the context of related evidence, the fetus' general capacity for exposure learning is reconsidered.