a1 Durham University
a2 City University London
a3 University of Bristol
Evidence regarding the use of inner speech by individuals with autism spectrum disorder (ASD) is equivocal. To clarify this issue, the current study employed multiple techniques and tasks used across several previous studies. In Experiment 1, participants with and without ASD showed highly similar patterns and levels of serial recall for visually presented stimuli. Both groups were significantly affected by the phonological similarity of items to be recalled, indicating that visual material was spontaneously recoded into a verbal form. Confirming that short-term memory is typically verbally mediated among the majority of people with ASD, recall performance among both groups declined substantially when inner speech use was prevented by the imposition of articulatory suppression during the presentation of stimuli. In Experiment 2, planning performance on a tower of London task was substantially detrimentally affected by articulatory suppression among comparison participants, but not among participants with ASD. This suggests that planning is not verbally mediated in ASD. It is important that the extent to which articulatory suppression affected planning among participants with ASD was uniquely associated with the degree of their observed and self-reported communication impairments. This confirms a link between interpersonal communication with others and intrapersonal communication with self as a means of higher order problem solving.
c1 Address correspondence and reprint requests to: David Williams, Department of Psychology, Durham University, Science Laboratories, South Road, Durham DH1 3LE, UK; E-mail: email@example.com.
This research was conducted as part of a City University Postdoctoral Fellowship (to D.M.W.). This paper was prepared at Durham University. We sincerely thank Charles Fernyhough for helpful comments on a draft of the paper and for stimulating conversations about inner speech, Sebastian Gaigg for help with participant recruitment and referring us to important literature concerning comparative psychology, and Heather Payne for her invaluable assistance with data entry and analysis. We also warmly thank all of the participants who took part in this study, as well as three anonymous reviewers for their constructive comments on an earlier version of the manuscript.