Effects of delay, length, and frequency on onset RTs and word durations: Articulatory planning uses flexible units but cannot be prepared

ABSTRACT

There is debate regarding whether most articulatory planning occurs offline (rather than online) and whether the products of off-line processing are stored in a separate articulatory buffer until a large enough chunk is ready for production. This hypothesis predicts that delayed naming conditions should reduce not only onset RTs but also word durations because articulatory plans will be buffered and kept ready. We have tested this hypothesis with young control speakers, an aphasic speaker , and an age and education-matched speaker, using repetition, reading and picture-naming tasks. Contrary to the off-line hypothesis, delayed conditions strongly reduced onset RTs, but had no benefit for word durations. In fact, we found small effects in the opposite direction. Moreover, frequency and imageability affected word durations even in delayed conditions, consistent with articulatory processing continuing on-line. The same pattern of results was found in CS and in control participants, strengthening confidence in our results. There is debate regarding whether most articulatory planning occurs offline (rather than online) and whether the results of off-line processing are stored in a separate articulatory buffer until a large enough chunk is ready for production. This hypothesis predicts that delayed naming conditions should reduce not only onset RTs but also word durations because articulatory plans will be buffered and kept ready. We have tested young control speakers, an aphasic speaker, and an age and education matched speaker, using repetition, reading and picture naming tasks. Contrary to the off-line hypothesis, delayed conditions strongly reduced onset RTs, but had no benefit for word durations. In fact, we found small effects in the opposite direction. Moreover, frequency and imageability affected word durations even in delayed conditions, consistent with articulatory processing continuing on-line. The same pattern of results was found in CS and in control participants, strengthening confidence in our results.

KEYWORDS:

• Word production
• aphasia
• articulatory buffer
• word durations
• effects of preparation
• word frequency
• word length

Acknowledgments

This work was supported by a Ph.D. studentship to Dinesh Ramoo granted by the University of Birmingham and by a master’s dissertation carried out by Priya Silverstein, also at the University of Birmingham. We would like to thank Dawn Jevons from the Stroke Association in South Birmingham for her assistance in recruiting the aphasic participant. We are extremely grateful to CS and his wife for many hours of graceful engagement. We are also grateful to the EPS small grant scheme for the support we received to complete the study (grant to Cristina Romani).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Note that all models make exactly the same assumptions regarding the different stages involved in speech production after lexical access (stage 2 above). In some models, the purpose of phonological encoding is to link phonemes to syllable structure (e.g., Levelt et al., 1999; Roelofs, 1996, 1997), while, in other models, phonemes are already organized into syllables at the lexical level since a syllabic organization is crucial for optimal storage and retrieval of information (e.g., see Romani et al., 2011). In models where phonemes are associated with syllables post-lexically, there is no clearly declared phonological output buffer, but filled syllabic frameworks might serve this function (see also Dell et al., 1993). In the original model by Levelt et al. (1999), an (articulatory) output buffer was placed after phonological encoding, at the level where articulatory syllable plans/gestures are retrieved and sequenced for production.

2 But there is some question about whether these effects are due to imageability, age of acquisition, or frequency given the overlap between these variables (see Cortese et al., 2018; Ellis & Monaghan, 2002).

3 Note that it is logically possible for an articulatory buffer to be used only optionally. However, the delayed naming conditions of our investigation are ideal to prepare and store articulatory plans. If an articulatory buffer is not used in these conditions, it is difficult to envision conditions in which it would be.

4 Different cells need to be in different colours for the table to be understandable.

Additional information

Funding

This work was supported by a Ph.D. studentship to Dinesh Ramoo granted by the University of Birmingham and by a master’s dissertation carried out by Priya Silverstein, at Aston University ; and by a small grant from the Experimental Psychology Society.