Irrelevant speech effects with locally time-reversed speech: Native vs non-native language

Area of Science:

• Cognitive Psychology
• Psycholinguistics
• Auditory Perception

Background:

• Irrelevant speech is a known distractor for short-term memory, particularly for visually presented information.
• The irrelevant speech effect (ISE) is influenced by factors such as language familiarity and speech intelligibility.
• Previous research has explored various manipulations of irrelevant speech, but the interplay of language, intelligibility, and playback direction requires further investigation.

Purpose of the Study:

• To investigate the irrelevant speech effect by manipulating participants' native language, the language of the irrelevant speech, and its playback direction.
• To differentiate the impact of local speech integrity from global integrity by using time-reversed speech.
• To determine how language familiarity and intelligibility interact to modulate the disruptive effect of irrelevant speech on short-term memory.

Main Methods:

• A factorial design was employed with German and Japanese participants (N=160).
• Participants performed a serial-recall task while exposed to irrelevant speech in their native or a foreign language, presented normally, time-reversed (locally or globally), or as pink noise.
• Speech stimuli varied in intelligibility based on segment duration and playback direction.

Main Results:

• All forms of irrelevant speech impaired recall accuracy compared to a pink-noise control.
• Intelligible native language speech, including locally time-reversed speech with short segments, was most disruptive.
• Incomprehensible irrelevant speech (long segments, backward playback) was less disruptive, with no difference between locally time-reversed and globally inverted speech, suggesting familiarity is key.

Conclusions:

• The irrelevant speech effect is robust across different languages and manipulations.
• Speech intelligibility and native language familiarity are critical factors determining the disruptive power of irrelevant speech.
• The impact of global acoustic inversion on memory is dependent on the listener's familiarity with the speech signal.