Temporal precision and the capacity of auditory–verbal short-term memory

ABSTRACT

The capacity of serially ordered auditory–verbal short-term memory (AVSTM) is sensitive to the timing of the material to be stored, and both temporal processing and AVSTM capacity are implicated in the development of language. We developed a novel “rehearsal-probe” task to investigate the relationship between temporal precision and the capacity to remember serial order. Participants listened to a sub-span sequence of spoken digits and silently rehearsed the items and their timing during an unfilled retention interval. After an unpredictable delay, a tone prompted report of the item being rehearsed at that moment. An initial experiment showed cyclic distributions of item responses over time, with peaks preserving serial order and broad, overlapping tails. The spread of the response distributions increased with additional memory load and correlated negatively with participants’ auditory digit spans. A second study replicated the negative correlation and demonstrated its specificity to AVSTM by controlling for differences in visuo-spatial STM and nonverbal IQ. The results are consistent with the idea that a common resource underpins both the temporal precision and capacity of AVSTM. The rehearsal-probe task may provide a valuable tool for investigating links between temporal processing and AVSTM capacity in the context of speech and language abilities.

KEYWORDS:

• Serial order memory
• Short-term memory
• Subvocal rehearsal
• Timing

Acknowledgement

We would like to thank Stephen Darling for providing a computerized version of the Visual Patterns Test.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. We refer to this task as the rehearsal-probe task because of the similarities with rehearsal in STM—namely the repetition of a memory sequence via inner speech. However, we are not suggesting that the subvocal repetition in this task is equivalent to natural rehearsal as it is used to recall sequences over short intervals, where there are no constraints on the timing or order of item repetition.

2. This equation produces a range of possible CSD values from 0 to the square root of 2. However, in the rehearsal-probe task, the minimum possible CSD is a function of the number of probes per item and the number of items in the sequence, and is greater than zero. This minimum value is stated in the Results section of each experiment.

3. We would like to thank Steve Majerus for suggesting this interpretation.