ReviewMemory for pure tone sequences without contour

- The Sustained Anterior Negativity (SAN) is an ERP component that indexes ASTM.
- The SAN could index contour instead of memory for individual sound stimuli.
- Impeding contour perception and encoding does not disrupt the SAN.
- The SAN reflects maintenance of individual sound stimuli in ASTM.

We presented pure tones interspersed with white noise sounds to disrupt contour perception in an acoustic short-term memory (ASTM) experiment during which we recorded the electroencephalogram. The memory set consisted of seven stimuli, 0, 1, 2, 3, or 4 of which were to-be-remembered tones. We estimated each participant׳s capacity, K, for each set size and measured the amplitude of the SAN (sustained anterior negativity, an ERP related to acoustic short-term memory). We correlated their K slopes with their SAN amplitude slopes as a function of set size, and found a significant link between performance and the SAN: a larger increase in SAN amplitude was linked with a larger number of stimuli maintained in ASTM. The SAN decreased in amplitude in the later portion of the silent retention interval, but the correlation between the SAN and capacity remained strong. These results show the SAN is not an index of contour but rather an index of the maintenance of individual objects in STM.This article is part of a Special Issue entitled SI: Auditory working memory.