The neural basis of implicit learning of task-irrelevant Chinese tonal sequence

Abstract

The present study sought to investigate the neural basis of implicit learning of task-irrelevant perceptual sequence. A novel SRT task, the serial syllable identification task (SSI task), was used in which the participants were asked to recognize which one of two Chinese syllables was presented. The tones of the syllables were irrelevant to the task but followed an underlying structured sequence. Participants were scanned while they performed the SSI task. Results showed that, at the behavioral level, faster RTs for the sequential material indicated that task-irrelevant sequence knowledge could be learned. In the subsequent prediction test of knowledge of the tonal cues using subjective measures, we found that the knowledge was obtained unconsciously. At the neural level, the left caudate, bilateral hippocampus and bilateral superior parietal lobule were engaged during the sequence condition relative to the random condition. Further analyses revealed that greater learning-related activation (relative to random) in the right caudate nucleus, bilateral hippocampus and left superior parietal lobule were found during the second half of the training phase compared with the first half. When people reported that they were guessing, the magnitude of the right hippocampus and left superior parietal lobule activations was positively related to the accuracy of prediction test, which was significantly better than chance. Together, the present results indicated that the caudate, hippocampus and superior parietal lobule played critical roles in the implicit perceptual sequence learning even when the perceptual features were task irrelevant.

The Neuroscience of Implicit Learning

“…Ling et al. (2015) did not find any difference in the time course of BG and H activation (both emerging after about 8 minutes), and Turk‐Browne et al. (2009) found a slightly delayed hippocampal response (after 48 seconds compared to 32 seconds for caudate).…”

“…Ling et al. (2015) examined learning of a sequence of Chinese tones (in Chinese native speakers) and found learning‐related activity in bilateral H, right caudate nucleus, and left superior parietal lobule. Jablonowski, Taesler, Fu, and Rose (2018) examined perceptual sequence learning of tones and found very precise learning related changes in bilateral H. Both studies used stringent tests to exclude any participants with sequence awareness.…”

“…The notable exceptions are left lateralisation in Yang and Li (2012) for implicit > explicit and Ling et al. (2015) for auditory perceptual sequence learning.…”

Facilitating Implicit Learning of Multiple Non-adjacent Dependencies Regardless of Language Experience: The Role of a Brief Pre-exposure

“…Although studies have argued that implicit learning does not always require attentional resources (Baker et al, 2004;Brosowsky et al, 2021;Jiang & Chun, 2001;Turk-Browne et al, 2008), a growing body of evidence suggests that at least some attentional resources must be available for successful implicit learning (e.g., Emberson et al, 2011;Ling et al, 2015;Riedel & Burton, 2006;Schneider et al, 2022;Toro et al, 2005). Toro et al (2005) found that in a speech statistical learning THE ROLE OF A BRIEF PRE-EXPOSURE IN IMPLICIT LEARNING 30 (SL) task, participants could successfully extract words in a recognition test after exposure by passive listening to the speech stream without other concurrent tasks.…”

Dynamic hippocampal functional connectivity responses to varying working memory loads following total sleep deprivation

“…We believe that the hippocampus plays a crucial role in reasoning regarding task uncertainty by moderating bias in information representation and the superior parietal lobule expectations (Rigoli et al, 2019). Similarly, the left hippocampus is engaged in guessing, along with the left superior parietal lobule, required for implicit perception learning (Ling et al, 2015).…”