# How sleep redraws phonemic categories after auditory selective adaptation

## TL;DR

This study shows that sleep changes how we perceive speech sounds after repeated exposure, reversing the effects of adaptation.

## Contribution

The study reveals that sleep alters phoneme category frequency, not just consolidating or clearing memory.

## Key findings

- Sleep does not consolidate selective adaptation but changes phoneme category frequency.
- Repeated exposure to a sound during wakefulness reduces its perception, but sleep increases it.
- The results support models with separate mechanisms for assimilative and contrastive effects.

## Abstract

After information has either been perceived or brought into working memory from long-term memory, it may remain active for hours or days. There is extensive evidence that sleep can consolidate newly learned material into long-term memory, and some recent work shows that sleep may also help clear out either unneeded or already established information. We examine the effect of sleep on a third type of information: adjustments to established speech categories caused by repeated exposure to a speech sound—selective adaptation. We find that sleep does not consolidate selective adaptation per se. Instead, sleep implements a change in phoneme category frequency to reflect the properties of the input—the many instances of the adapting sound that had been presented repeatedly. While adaptation temporarily reduces the perception of tokens similar to the repeating sound, sleep increases their perception, producing a “reverse adaptation” pattern. The results constrain models of phoneme category adjustment, favoring those that have separate mechanisms for assimilative versus contrastive effects over those with a single mechanism for both types of effects.

The online version contains supplementary material available at 10.3758/s13423-025-02819-x.