Research ArticlePSYCHOLOGICAL SCIENCE

Nonadjacent dependency processing in monkeys, apes, and humans

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Science Advances  21 Oct 2020:
Vol. 6, no. 43, eabb0725
DOI: 10.1126/sciadv.abb0725
  • Fig. 1 Visual representation of each element and possible transitions between them for each sequence type (bracketed elements apply only to Non-AD condition), with examples.

    Numbers below category label indicate possible pitch variants. Y axis values in Familiarization row refer to pitch variant 1 of each element. Arrow color represents sequence transitions corresponding to a grammar (AXB and CXD) (see table S1 for summary of all possible sequence configurations per condition).

  • Fig. 2 Participant responses for each experiment.

    Left: Mean duration spent looking toward the speaker for each primate species in each condition and each sequence type: dots = individuals; bars = group. Right: Response accuracy for human subjects: Bars represent SE.

  • Table 1 Relative fits (in descending order of WAIC weight) for each statistical model corresponding to our a priori hypotheses regarding patterns of gaze duration (see the “Statistical analysis” section in Materials and Methods).

    “Varies” does not assume directionality in relation to other sequence types; this was instead determined by inspecting posterior distributions.

    ModelSpeciesConditionWAICWAIC weight
    FS = GS, VS variesMarmosetsNonadjacent138.50.67
    FS, GS, and VS vary140.50.24
    FS = VS, GS varies143.20.06
    GS = VS, FS varies146.30.01
    Null model (FS = GS = VS)147.10.01
    FS = GS, VS variesMarmosetsAdjacent189.60.52
    FS, GS, and VS vary191.00.25
    FS = VS, GS varies191.50.20
    GS = VS, FS varies196.90.01
    Null model (FS = GS = VS)196.90.01
    FS = GS, VS variesChimpanzeesNon-adjacent239.10.91
    FS, GS, and VS vary243.90.09
    Null model (FS = GS = VS)255.80.00
    FS = VS, GS varies264.90.00
    GS = VS, FS varies268.40.00
    FS = GS, VS variesChimpanzeesAdjacent332.80.82
    FS, GS, and VS vary337.70.07
    GS = VS, FS varies338.10.06
    Null model (FS = GS = VS)339.80.03
    FS = VS, GS varies340.90.01
  • Table 2 Estimated posterior distributions for best-fitting model of each condition presented in Table 1.

    Coefficients represent predicted total time spent looking toward the speaker after FS/GS, and VS relative to FS/GS.

    SpeciesConditionParameterMeanSD5.5% CI94.5% CI
    MarmosetsNonadjacentFS/GS0.290.150.070.53
    VS0.610.280.171.03
    MarmosetsAdjacentFS/GS0.300.160.030.52
    VS0.790.380.161.38
    ChimpanzeesNon-adjacentFS/GS0.490.280.010.88
    VS1.541.09−0.193.20
    ChimpanzeesAdjacentFS/GS1.280.670.202.25
    VS1.270.850.022.60

Supplementary Materials

  • Supplementary Materials

    Nonadjacent dependency processing in monkeys, apes, and humans

    Stuart K. Watson, Judith M. Burkart, Steven J. Schapiro, Susan P. Lambeth, Jutta L. Mueller, Simon W. Townsend

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    • Figs. S1 and S2
    • Tables S1 to S4

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