Lack of Cross-Modal Effects in Dual-Modality Implicit Statistical Learning

Wendian Shi,Yang Lu,Xiujun Li,Christopher M. Conway,Xudong Zhao

doi:10.3389/fpsyg.2018.00146

Abstract

A current controversy in the area of implicit statistical learning (ISL) is whether this process consists of a single, central mechanism or multiple modality-specific ones. To provide insight into this question, the current study involved three ISL experiments to explore whether multimodal input sources are processed separately in each modality or are integrated together across modalities. In Experiment 1, visual and auditory ISL were measured under unimodal conditions, with the results providing a baseline level of learning for subsequent experiments. Visual and auditory sequences were presented separately, and the underlying grammar used for both modalities was the same. In Experiment 2, visual and auditory sequences were presented simultaneously with each modality using the same artificial grammar to investigate whether redundant multisensory information would result in a facilitative effect (i.e., increased learning) compared to the baseline. In Experiment 3, visual and auditory sequences were again presented simultaneously but this time with each modality employing different artificial grammars to investigate whether an interference effect (i.e., decreased learning) would be observed compared to the baseline. Results showed that there was neither a facilitative learning effect in Experiment 2 nor an interference effect in Experiment 3. These findings suggest that participants were able to track simultaneously and independently two sets of sequential regularities under dual-modality conditions. These findings are consistent with the theories that posit the existence of multiple, modality-specific ISL mechanisms rather than a single central one.

Highlights

Human learners show sensitivity to environmental regularities across multiple perceptual modalities and domains even without being aware of what is learned (Aslin and Newport, 2009; Emberson and Rubinstein, 2016)
Dual-Modality Implicit Statistical Learning who were exposed to letter strings generated from an artificial grammar
In Experiment 1, we presented visual and auditory streams in isolation to provide baseline levels of unimodal performance used as comparisons for Experiments 2 and 3

Summary

Introduction

Human learners show sensitivity to environmental regularities across multiple perceptual modalities and domains even without being aware of what is learned (Aslin and Newport, 2009; Emberson and Rubinstein, 2016) This ability, referred to as implicit statistical learning (ISL), is a ubiquitous foundational cognitive ability thought to support diverse complex functions (Guo et al, 2011; Thiessen and Erickson, 2015). Participants showed evidence of learning this structure implicitly, and could apparently transfer their knowledge of the legal regularities from one letter vocabulary (e.g., M, R, T, V, X) to another (e.g., N, P, S, W, Z) as long as the underlying grammar used for both was the same This effect has been replicated many times, with transfer being demonstrated not just across letter sets (Shanks et al, 1997), and across perceptual modalities (Tunney and Altmann, 2001). Given that ISL occurs with perceptually diverse input, it is possible that what underlies ISL is a single, central mechanism that treats all types of input stimuli (e.g., tones, shapes, and syllables) as equivalent beyond the statistical structure of the input itself

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