Research ArticlePSYCHOLOGICAL SCIENCE

Do marmosets understand others’ conversations? A thermography approach

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Science Advances  03 Feb 2021:
Vol. 7, no. 6, eabc8790
DOI: 10.1126/sciadv.abc8790
  • Fig. 1 Experimental setup.

    Schematic representation of the experimental setup with the phases, periods, and subphases of the experiment. During phase A (yellow), marmosets were sitting on a perch in the front of the compartment on the left-hand side. During phase B (green, only after test conditions), marmosets could choose to explore the compartment on the right-hand side or go back to the home enclosure (via the black sliding doors that were opened after phase A). The baseline period lasted for 60 s before the onset of the playback stimulus. The playback stimulus started at time point 0 and lasted for 60 s (dotted lines on timeline). Temperature values were only extracted from subphases pre and post (red arrows on timeline: 30 to 80 s after stimulus onset).

  • Fig. 2 Overall thermal reaction.

    Changes in arousal in response to the playbacks. Boxplots showing temperature changes relative to baseline (i.e., session-specific mean minimum nasal temperature) by condition and sexstatus [breeders, female helpers (fh), and male helpers (mh)]. Bold black bars indicate estimated marginal means based on model 1 (see table S5), and gray points represent centered data points. Note that negative values represent a decrease in nasal temperature and thus an increase in arousal. *P ≤ 0.05, ***P ≤ 0.001.

  • Fig. 3 Additive effect.

    Boxplots comparing the simulated additive effect (green outlined boxplots) and the measured reaction after the interaction playback (black outlined boxplots) for the positive and negative condition split up by sexstatus classes [breeders, female helpers (fh), and male helpers (mh)]. Bold black bars indicate estimated marginal means based on model 2a (see table S5). **P ≤ 0.01, ***P ≤ 0.001; NS, not significant.

  • Fig. 4 Preference for cooperative individuals.

    The probability of not yet having looked into the mirror after the positive (blue) and negative (orange) playback (Kaplan-Meier curves). N = 37 with 30 events of looking into the mirror. Dashed lines indicate median survival pointers and show that the median latency to look into the mirror was 13.6 s after the positive playback but 37.9 s after the negative playback.

  • Table 1 Type II analyses of deviance tables for models 1 to 2b.

    Bold values indicate P < 0.05. Only the highest-order (interaction) terms warrant biological interpretation.

    Fixed factorsχ2dfP
    Model 1: Centered nasal temperature
    Condition (pos-int, neg-int, fc, ct, gnaeh)9.40240.0518
    Subphase (pre, post)5.34410.0208
    Sexstatus (breeders, fh, mh)19.2552<0.0001
    Condition*subphase87.0734<0.0001
    Condition*sexstatus7.43280.4908
    Subphase*sexstatus263.8892<0.0001
    Condition*subphase*sexstatus157.3828<0.0001
    Model 2a: Nasal temperature (Cartesian product dataset)
    Condition (pos-int, pos-add, neg-int, neg-add)87.5503<0.0001
    Sexstatus (breeders, fh, mh)11.46120.003
    Condition*sexstatus28.4686<0.0001
    Model 2b: Nasal temperature (Cartesian product dataset with means per session)
    Condition (pos-int, pos-add, neg-int, neg-add)13.132630.004
    Sexstatus (breeders, fh, mh)15.443520.0004
    Condition*sexstatus4.141660.658
  • Table 2 Summary table model 6.

    Bold values indicate P < 0.05. Cox proportional hazards model with random intercept on latency to look into mirror.

    Model 6: Latency to looking into mirror
    Fixed factorsβSEHR [95% CI]zP
    Condition (neg-int)−2.8661.0580.057 [0.007, 0.453]−2.710.007
    Direction of thermal
    change
      Decrease and increase
    versus none
    −0.3040.2180.738 [0.481, 1.132]−1.390.160
      Decrease versus
    increase
    −0.6240.4120.536 [0.239, 1.200]−1.520.130
    Order (2)−0.1260.9750.882 [0.130, 5.964]−0.130.900
    Condition*order
    [Neg-int*order (2)]
    3.2951.87626.988 [0.683, 1066.107]1.760.079

Supplementary Materials

  • Supplementary Materials

    Do marmosets understand others’ conversations? A thermography approach

    R. K. Brügger, E. P. Willems, J. M. Burkart

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    This PDF file includes:

    • Sections S1 to S4
    • Figs. S1 and S2
    • Tables S1 to S8
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