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. Author manuscript; available in PMC: 2021 Dec 1.
Published in final edited form as: Psychophysiology. 2020 Oct 13;57(12):e13673. doi: 10.1111/psyp.13673

Table 2.

Effects of the still-face challenge on cardiorespiratory parameters in infants who completed one versus two still-face trials

Time Group by Time Sign. Covariates (p)a
F df P F df p
RR-interval 80.68 4,381 <.001 85.68 2,287 <.001 Physical activity(−) (<.001),
Age (.006), Length (.013),
Race, Black (.049)
TWA 16.05 4,461 <.001 7.72 2,283 <.001
lnRSA 6.10 4,368 <.001 4.35 2,251 .014 Physical activity (<.001),
Age (<.001)
lnRSA/VTc 32.43 4,331 <.001 17.84 2,246 <.001 Physical activity (<.001),
Ethnicity, Hispanic (.002),
Maternal Education (.022)
VT 11.49 4,290 <.001 12.45 2,250 <.001 Physical activity (<.001),
Age (.030), Weight (<.001),
Race, White (<.001)
TTOT 15.06 4,372 <.001 5.18 2,252 .006 Physical activity (<.001)
V’E 4.06 4,290 .003 6.91 2,248 <.001 Physical activity (<.001),
Age (.040), Weight (<.001),
Race, White (<.001)
Physical activity 221.3 4,353 <.001 28.66 2,278 <.001 Sex, Male(−) (.050)
Negative affect 176.6 4,443 <.001 107.0 2,288 <.001 Physical activity (<.001)
Positive affect 141.1 4,452 <.001 59.09 2,288 <.001 Physical activity (<.001)
a

Covariates were maternal education level, infant age, sex, height, weight, race/ethnicity, physical activity; physical activity served as a within-individual covariate; all associations positive, except for (−)

Abbreviations: SFP, Still-Face Paradigm; RR-Interval, interval between adjacent R-waves of the ECG; TWA, T-wave amplitude; RSA, respiratory sinus arrhythmia; RSA/VTc, RSA adjusted for tidal volume (VT) and total breath duration (TTOT); V’E, minute ventilation