| The present studies assessed the effects of shaping procedures using two different percentile schedules of reinforcement on the amplitude of textual vocal behavior of typically-developing adults. Changes in vocal amplitude during extinction were assessed following conditions in which vocal amplitude was shaped to louder- and quieter-than-baseline levels. Participant self-reports of their interpretations of the conditions and their effects were also collected. Experiments' terminal shaping criteria were met during 13 sessions by 11 different participants, out of the 36 total sessions completed by 27 participants. Participants enrolled in experiments with successively louder vocal amplitude criteria met terminal shaping criteria approximately as often as those who were enrolled in experiments with successively quieter vocal amplitude criteria. Participants' vocal amplitude level typically increased during extinction conditions, regardless of participants' experimental history of vocal amplitude being shaped to louder- or quieter-than-baseline levels. This was accompanied by increased variability in vocal amplitude, to both louder- and quieter-than-baseline volumes. The present study extended the existing literature on shaping the amplitude of vocal behavior by eliminating the inclusion of vocal instructions and implementing both louder- and softer-than-baseline shaping phases within and across multiple participants. In addition, the method provides a foundation for the further examination of phenomena related to response differentiation of speech, especially the effects on behavior during shaping and extinction. |
