Research ArticleCOGNITIVE NEUROSCIENCE

Infant cognition includes the potentially human-unique ability to encode embedding

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Science Advances  21 Nov 2018:
Vol. 4, no. 11, eaar8334
DOI: 10.1126/sciadv.aar8334
  • Fig. 1 Illustration of different sequential regularities with increasing structural complexity.

    (A) Example of a two-element sequence implementing a linear structure with adjacent relations. (B) Example of a three-element sequence implementing a linear structure with nonadjacent relations. (C) Example of a four-element sequence implementing an embedded structure with nested relations. The processing of the outer dependency (red) is temporarily interrupted (1) for processing an inner dependency (black) of a similar kind. (D) Example of a six-element sequence implementing an embedded structure with multiple nested relations. The processing of each outer dependency (yellow and red) is temporarily interrupted (1, 2) for processing an inner dependency of a similar kind (red and black).

  • Fig. 2 Experimental paradigm and sequence structures.

    (A) Example of a center-embedded structure from natural language containing nested dependencies (blue lines), forming one level of embedding. (B) Illustration of the oddball paradigm containing tone sequences as frequent standards (S; blue) and infrequent deviants (D; orange). (C) Examples of five-tone sequences (experiment 1): Blue sequences indicate both standard forms, involving nested dependencies, which implement one level of center-embedding. A1, A2, B1, and B2 represent the rule-defining tones, and C is the center-marker at 1500 Hz. Orange sequences indicate both deviant forms, which violate the nested rules by exchanging the order of the last two tones. Note that the last two tones that define the rule violation in the deviant have previously appeared in the standards’ second form and are thereby not informative about the rule per se. (D) Examples of seven-tone sequences (experiment 2): Blue sequences indicate both standard forms, involving nested dependencies, which implement two levels of center-embedding. A1, A2, A3, B1, B2, and B3 represent the rule-defining tones, and C is the center-marker at 2100 Hz. Orange sequences indicate both deviant forms, which violate the nested rules by exchanging the order of the last two tones.

  • Fig. 3 ERP results of experiment 1.

    (A) Control analysis: Grand-average ERP responses for standards (blue) plotted against rule deviants (orange) for anterior (A), central (C), and posterior (P) regions of interest (ROI). Negativity is plotted upward. The y axis corresponds to onset of tone 2. Timing of rule-conforming tones 2 and 3 is illustrated by gray rectangles at the bottom of the illustration. (B) Analysis of rule violation: Grand-average ERP responses for standards (blue) plotted against rule deviants (orange). Negativity is plotted upward. Window of significant condition effects (120 to 480 ms) is highlighted in light orange. The y axis corresponds to onset of tone 4. Timing of rule-violating tones 4 and 5 is illustrated by gray rectangles at the bottom of the illustration. MMR, mismatch response.

  • Fig. 4 ERP results of experiment 2.

    (A) Control analysis: Grand-average ERP responses for standards (blue) plotted against rule deviants (orange) for anterior (A), central (C), and posterior (P) regions of interest (ROI). Negativity is plotted upward. The y axis corresponds to onset of tone 3. Timing of rule-conforming tones 3 and 4 is illustrated by gray rectangles at the bottom of the illustration. (B) Analysis of rule violation: Grand-average ERP responses for standards (blue) plotted against rule deviants (orange). Negativity is plotted upward. Window of significant condition effects (210 to 570 ms) is highlighted in light orange. The y axis corresponds to onset of tone 6. Timing of rule-violating tones 6 and 7 is illustrated by gray rectangles at the bottom of the illustration.

  • Fig. 5 Sequence variability of experiment 2.

    (A) Standard sequences (blue): Variability of 24 standard sequences illustrated by blue bars at the tone frequency (in Hz, y axis) for each tone of the sequence (x axis). Each inset row depicts one sequence. The outlined rectangles at the first and second sequences of the deviants and standards illustrate that the rule-violating part of the deviant is also present in the corresponding standards’ second form. (B) Deviant sequences (orange): Variability of 24 deviant sequences illustrated by orange bars at the tone frequency (in Hz, y axis) for each tone of the sequence (x axis). Each inset row depicts one sequence.

Supplementary Materials

  • Supplementary Materials

    This PDF file includes:

    • Table S1. Standard sequences of experiment 1.
    • Table S2. Deviant sequences of experiment 1.
    • Table S3. Standard sequences of experiment 2.
    • Table S4. Deviant sequences of experiment 2.

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