VARYING INTER-STIMULUS AND INTER-TRIAL INTERVALS DURING A TRANSLATIONAL EXTENSION OF STIMULUS-STIMULUS PAIRING

Abstract

Stimulus-stimulus pairing (SSP) is a respondent conditioning procedure used to elicit vocalizations in children with language delays. Unfortunately, many of the studies published fail to maximize its success, most likely because specific parameters that generate better outcomes are unknown. One factor that may impact SSP efficacy is the relative duration of the inter-trial interval (ITI) and/or the inter stimulus interval (ISI). To investigate this, the present study varied the ITI from 20 to 60 s while also varying the ISI to keep it proportional to the ITI. Nine typically developing children, aged 15 to 21 months, were randomly assigned to one of three experimental groups. The study alternated between pairing (sound model, followed by food delivery) and control (no programmed pairing between the sound model and food delivery) trials for all subjects in a trace conditioning procedure. The pairing condition led to a slightly higher percentage of trials with vocalizations across all subjects. Subjects in the 20-s ITI group had the highest rates of vocalizations, followed by those in the 60-s ITI group and the 30-s ITI group. However, subjects in the 60-second ITI group were most likely to approach the apparatus, as would be expected perthe delay reduction hypothesis. In conclusion, the effectiveness of SSP depends, in part, on the relative temporal contiguity of events with longer ITIs (e.g., 60 s) producing more approaches to the sound model (NS/CS), although the shortest ITI group had the highest rates of vocalizations in the current study.