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Long Term Memory for Noise: Evidence of Robust Encoding of Very Short Temporal Acoustic Patterns

View Article: PubMed Central - PubMed

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 CNs were implicitly presented multiple times within a block, and implicit recognition of these target CNs was tested 4 weeks later using a similar cyclic/non-cyclic discrimination task. Furthermore, robustness of implicit recognition memory was tested by presenting participants with looped (shifting the origin) and scrambled (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.

Meaningless 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.

Successful encoding and long-term implicit recognition of meaningless patterns may strongly depend on individual attention and auditory discrimination abilities.

No MeSH data available.


Relationship between discrimination rates of CNs in the testing session and learning efficiency (represented as a') for all participants (n = 25).
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Figure 6: Relationship between discrimination rates of CNs in the testing session and learning efficiency (represented as a') for all participants (n = 25).

Mentions: Individual discrimination performances in the testing phase as a function of discrimination efficiencies (quantified as a') during the learning phase for learned CNs and modified forms of the learned CNs were examined. Linear regression between hit rate(testing) and a'(learning) showed that a' during learning did predict later detection of cyclicity in looped [R2 = 0.272, slope = 81.95, intercept = 5.71, p = 0.0075] and scrambled CNs [R2 = 0.366, slope = 102.59, intercept = −13.73, p = 0.0013]. The correlation between a' during learning and discrimination rate for intact learned CNs [R2 = 0.153, slope = 60.36, intercept = 26.32, p = 0.053] was just below significance. These results show that a' during learning was a significant predictor of further accuracy to discriminate modified versions of learned CNs 4 weeks later. This is shown in Figure 6.


Long Term Memory for Noise: Evidence of Robust Encoding of Very Short Temporal Acoustic Patterns
Relationship between discrimination rates of CNs in the testing session and learning efficiency (represented as a') for all participants (n = 25).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121232&req=5

Figure 6: Relationship between discrimination rates of CNs in the testing session and learning efficiency (represented as a') for all participants (n = 25).
Mentions: Individual discrimination performances in the testing phase as a function of discrimination efficiencies (quantified as a') during the learning phase for learned CNs and modified forms of the learned CNs were examined. Linear regression between hit rate(testing) and a'(learning) showed that a' during learning did predict later detection of cyclicity in looped [R2 = 0.272, slope = 81.95, intercept = 5.71, p = 0.0075] and scrambled CNs [R2 = 0.366, slope = 102.59, intercept = −13.73, p = 0.0013]. The correlation between a' during learning and discrimination rate for intact learned CNs [R2 = 0.153, slope = 60.36, intercept = 26.32, p = 0.053] was just below significance. These results show that a' during learning was a significant predictor of further accuracy to discriminate modified versions of learned CNs 4 weeks later. This is shown in Figure 6.

View Article: PubMed Central - PubMed

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 CNs were implicitly presented multiple times within a block, and implicit recognition of these target CNs was tested 4 weeks later using a similar cyclic/non-cyclic discrimination task. Furthermore, robustness of implicit recognition memory was tested by presenting participants with looped (shifting the origin) and scrambled (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.

Meaningless 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.

Successful encoding and long-term implicit recognition of meaningless patterns may strongly depend on individual attention and auditory discrimination abilities.

No MeSH data available.