What characterizes changing-state speech in affecting short-term memory? An EEG study on the irrelevant sound effect

Area of Science:

• Cognitive Neuroscience
• Auditory Perception

Background:

• The irrelevant sound effect (ISE) demonstrates that changing-state sounds impair verbal short-term memory, while steady-state sounds do not.
• This effect is linked to the distinct auditory tokens within changing-state sounds.

Purpose of the Study:

• To investigate the neurophysiological differences between detrimental changing-state speech and ineffective steady-state speech using EEG.
• To understand how these sound types affect serial recall performance and brain activity.

Main Methods:

• An EEG experiment with 16 participants was conducted.
• Evoked, induced, and spectral brain activity were analyzed during memory tasks involving 1-token (steady-state) and 3-token (changing-state) speech sequences.
• Serial recall performance was measured.

Main Results:

• The irrelevant sound effect was associated with reduced gamma-band activation (50-60 Hz, 50-100 ms post-stimulus) specifically induced by the auditory tokens.
• This attenuated activation correlated with impaired serial recall performance.

Conclusions:

• Changing-state speech disrupts cognitive processes, likely interfering with the serial binding of memory items during target presentation.
• Gamma-band activity modulation is a key neurophysiological correlate of the irrelevant sound effect on verbal short-term memory.