Using discrete trial training with progressive time delay prompting to teach children with autism spectrum disorder to tact phonemes

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


School of Psychology


Faculty of Health, Engineering and Science

First Advisor

Dr Eyal Gringart

Second Advisor

Professor Craig Speelman


Discrete trial training (DTT) and progressive time delay prompting (PTD) are effective techniques for teaching new skills to children with autism spectrum disorder (ASD). However, these methods have not yet been applied to systematic teaching of phonemes to children with ASD. As phoneme recognition (i.e. recognising the sounds the letters of the alphabet make when spoken) is an essential foundational literacy skill, and as there currently exists a large gap in reading ability between children with ASD and their neurotypical same age peers, further investigation was warranted. As phoneme recognition is one small subskill of reading competency, it was also investigated whether phoneme recognition transferred to the ability to sound out and blend consonant-vowel-consonant (CVC) words (i.e. cat, tip, pat).

A single subject research design with multiple baseline was implemented to investigate whether DTT and PTD were effective methods of teaching children with ASD to tact (or label) phonemes or numerals. Numerals were included as a second target stimuli in order to a) comprehensively test the efficacy of DTT and PTD to different foundational education skills and b) clearly attribute any CVC words mastered to being taught tacting of phonemes using DTT and PTD rather than an extraneous variable (i.e. classroom teaching). It was hypothesised that all participants would master, retain and generalise some stimuli, but only participants taught tacting of phonemes would go on to master sounding out and blending of CVC words. Participants (n = 10) were children aged 5-12 with an ASD diagnosis enrolled in full time primary schooling who were randomly assigned to one of three cohorts; literacy cohort ( n = 4), numeracy cohort (n = 4) or control cohort (n = 2). Control cohort participants engaged in pre and post testing, with treatment as usual (exposure to typical class curricula) for the remainder of the data collection period. Participants in the literacy and numeracy cohorts underwent four phases of experimental analysis: Baseline, Intervention (where DTT and PTD were used to systematically teach tacting of phonemes or numerals to mastery), CVC probe (probing for transfer of learned stimuli to the ability to sound out and blend CVC words) and Generalisation (probing for transfer of learned stimuli to people, place and materials).

Results demonstrated that DTT and PTD are effective methods of teaching tacting of phonemes and numerals, with participants mastering, retaining and generalising an average of 8.7 phonemes and 9.5 numerals over a 16 week period. The control cohort acquired an iv AUTISM, ABA, AND LITERACY average of 2 phonemes or numerals over a 24 week period as a function of being engaged in typical classroom instruction. As hypothesised, only participants from the literacy cohort demonstrated an ability to sound out and blend CVC words during the second phase of the study.

The current research adds support to the effectiveness of DTT and PTD in teaching children with ASD to acquire new skills. Further, the research extends this efficacy into a new domain of skill acquisition, the ability to tact phonemes and numerals. This research then provides a discussion in relation to the educational and social significance and implications of the results, and the implications for clinical practice in Western Australia, where the research was conducted. Lastly, limitations of the current research and directions for future research are discussed.

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