Date of Award


Document Type


Degree Name

Master of Science (M.S.) in Speech with Emphasis in Speech Pathology


Speech and Hearing Sciences

Physical Description

1 online resource (4, vi, 60 leaves)


Children with mental disabilities, Deaf children, Audiometry




Mentally retarded children demonstrate an abnormally high incidence of hearing impairment, and many, particularly those with IQs below 40, are difficult for audiologists to test. Consequently, there is great need among this population for investigating response modes and conditioning of responses to auditory stimuli. A review of the literature reveals no studies of echoic vocalization as a conditioned response mode to pure tone stimuli among the retarded. In this study, a heterogenous sample of 13 moderately and severely retarded children ranging in age from 7 years 7 months to 16 years 3 months were compared on two response modes to suprathreshold pure tone signals of 500 and 4000 Hz: (1) dropping poker chips, and (2) echoic vocalization (EVR). All subjects received both treatments but were divided into Groups A and B, the former receiving Treatment One (object dropping) first, the latter receiving Treatment Two (EVR) first. Operant procedures combined social and tangible reinforcement in each treatment to achieve stimulus control without specific verbal instructions. EVR included two unusual stages: (1) conditioning of imitations to the experimenter’s vocalizations, usually /a/ and (2) conditioning of response transfer from vocal to pure tone stimuli. Acquisition and extinction to first 500, then 4000 Hz proceeded sequentially within each treatment. Acquisition criterion for vocal and pure tone stimuli was eight consecutive responses. Extinction criterion was failure to respond to six out of eight tonal stimuli following withdrawal of reinforcement. Eleven of the 13 children achieved acquisition criterion for both response modes, with only three of the older subjects encountering substantial difficulty in response transfer in Treatment Two. Differences in acquisition data between treatments were not significant. Three times as much extinction occurred with EVR in Treatment Two than with object dropping in Treatment One, but there was a tendency toward more false responses in the latter mode. Otherwise, data up to achievement of extinction criterion in the extinction phases did not differ significantly between treatments Order of presentation of treatment and frequency of the pure tone stimuli were not significant factors in the results. It was concluded that despite substantially greater occurrence of extinction following withdrawal of reinforcement as compared with object dropping, echoic vocalization response has been shown to be an effective, practical response mode to suprathreshold pure tone stimuli among the children in this sample. It was recommended that further investigation with EVR be directed toward: (1) the feasibility of eliminating response transfer by use of verbal assistance and direct conditioning of EVR to pure tones; (2) if response transfer is necessary, comparison of older and younger retardates on that procedure; (3) the possibility of increasing resistance to extinction in EVR through visual reinforcement; (4) comparison of EVR and object dropping on threshold determination among MR children; (5) the practicability of paring EVR and object dropping response modes; and (6) investigation of other forms of both breath expulsion and breath inspiration as response modes to pure tone stimuli among mentally retarded children.


Portland State University. Dept. of Speech and Hearing Sciences

Persistent Identifier