title: Long Term Memory for Noise: Evidence of Robust Encoding of Very Short Temporal Acoustic Patterns.
abstract: Recent research has demonstrated that humans are able to implicitly encode and retain repeating patterns in meaningless auditory noise. Our study aimed at testing the robustness of long-term implicit recognition memory for these learned patterns. Participants performed a cyclic/non-cyclic discrimination task, during which they were presented with either 1-s cyclic noises (CNs) (the two halves of the noise were identical) or 1-s plain random noises (Ns). Among CNs and Ns presented once,target CNswere implicitly presented multiple times within a block, and implicit recognition of thesetarget CNswas tested 4 weeks later using a similar cyclic/non-cyclic discrimination task. Furthermore, robustness of implicit recognition memory was tested by presenting participants withlooped(shifting the origin) andscrambled(chopping sounds into 10- and 20-ms bits before shuffling) versions of the target CNs. We found that participants had robust implicit recognition memory for learned noise patterns after 4 weeks, right from the first presentation. Additionally, this memory was remarkably resistant to acoustic transformations, such as looping and scrambling of the sounds. Finally, implicit recognition of sounds was dependent on participant's discrimination performance during learning. Our findings suggest that meaningless temporal features as short as 10 ms can be implicitly stored in long-term auditory memory. Moreover, successful encoding and storage of such fine features may vary between participants, possibly depending on individual attention and auditory discrimination abilities.Significance StatementMeaningless auditory patterns could be implicitly encoded and stored in long-term memory.Acoustic transformations of learned meaningless patterns could be implicitly recognized after 4 weeks.Implicit long-term memories can be formed for meaningless auditory features as short as 10 ms.Successful encoding and long-term implicit recognition of meaningless patterns may strongly depend on individual attention and auditory discrimination abilities.
authors.affiliation: Centre de Recherche Cerveau et Cognition, Centre National de la Recherche Scientifique UMR 5549Toulouse, France; Faculty of Medicine, Purpan, University of Toulouse III Paul SabatierToulouse, France.
authors.forename: Jayalakshmi
authors.initials: J
authors.lastname: Viswanathan
authors.affiliation: Centre de Recherche Cerveau et Cognition, Centre National de la Recherche Scientifique UMR 5549Toulouse, France; Faculty of Medicine, Purpan, University of Toulouse III Paul SabatierToulouse, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Rémy
authors.affiliation: Centre de Recherche Cerveau et Cognition, Centre National de la Recherche Scientifique UMR 5549 Toulouse, France.
authors.forename: Nadège
authors.initials: N
authors.lastname: Bacon-Macé
authors.affiliation: Centre de Recherche Cerveau et Cognition, Centre National de la Recherche Scientifique UMR 5549Toulouse, France; Faculty of Medicine, Purpan, University of Toulouse III Paul SabatierToulouse, France.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Thorpe
keywords: STDP; implicit learning; long-term memory; meaningless stimuli; temporal resolution