Sound as a reinforcer for infants' manipulations of toys.

Abstract

We investigated the effectiveness of sound as a reinforcer of manipulative responses by infants. Fifty subjects, 4-12 months of age, were presented five different toys: (a) a barbell rattle; (b) a rattle shaped in the form of a whale; (c) a bracelet with bells; (d) a rubber pig that squeaked when squeezed; and (e) a drum that resonated when struck. The noise-making component of another set of identical toys was either removed or modified so that shaking the toy or striking it resulted in either no sound or a sharply attenuated one. Toys were presented singly for two minutes. Two observers, each equipped with a microswitch, recorded manipulations of each toy. The data were registered on magnetic tape and later displayed graphically. Noisy toys were manipulated significantly more frequent than quiet ones with infants from 6 to 10 months old. They were relatively more responsive to noisy toys than were our younger and older subjects. Since infants show a strong proclivity to make sounds, a reasonable assumption is that this propensity could be incorporated into a behavioral test for hearing. Simply stated, infants with profound hearing losses would not prefer noisy toys over quiet ones. Further research would be required for adapting the test situation to infants with more moderate hearing losses.