Electronic Supplementary Material
Oxytocin Shapes Parental Motion during Father-Infant Interaction
Omri Weisman*, Emilie Delaherche, Margot Rondeau, Mohamed Chetouani, David
Cohen, Ruth Feldman
*To whom correspondence should be addressed: omriwei@yahoo.com
Supplement S1: Participants.
Thirty-five healthy fathers (average age 29.7 years, SD = 4.2, range 22 – 38)
participated with their five-month old infants (SD = 1.25 months, range 4–8) in two
lab visits, a week apart (total N = 70). Females were not enrolled to this study due to
physiological effects of OT manipulation (e.g., uterus contraction) and the need to
control for menstrual cycle. Fathers' exclusion criteria included smoking, chronic
mental or physical illness, and medication intake. All fathers were educated middleclass and married to the infant's mother. Infants (18 girls) were healthy, and 68.5%
were firstborns and exclusion criteria included premature birth, labor- or birth-related
complications, multiple birth, or illness.
Supplement S2: Description of analysis of parent-infant motion.
Parent-infant motion analysis was conducted based on a randomly selected 2-minuteslong vignette extracted from the first 3 minutes free-play recording, using the
following procedure: The position of the father head was obtained with ear tracking
(figure 1a). A template of the father ear was initialized on the first frame of each
session. The position of the ear in the following frames was obtained by template
matching [1]. A search area of 60x60 pixels was chosen according to the position of
the ear in the last frame. The similarity between the template and all sub-regions in
the search area was computed. The position of the ear corresponds to the point with
the highest similarity with template (the dark spot on the similarity map; figure 1b).
The position of the infant head was set manually on the first frame of all sessions,
between the two eyes. Distance was normalized according to a scale (diameter of the
rotating device of the chair; d') to take into account the zoom variations in the various
sessions (figure 1c). Three dyads were discarded from final analysis due to
unsuccessful recording (1 dyad), father holding the infant during the experiment (1
dyads), and because ear-tracking was not feasible (1 dyad). Three variables were
computed from the analysis: the distance between father and infant, the speed, and the
acceleration of the father. Several statistic parameters were extracted for each
variable: mean, median, minimum, time to minimum (time till minimum was
reached), maximum, time to maximum, range, and standard deviation. The distance d
(distance of father head to baby head) is similar to father’s head position according to
his baby’s head since 5-month-old infant has minimal movements in the d direction.
We can therefore approximate speed, the derivative of d, as similar to father head
motion.
Supplement S3: Description of analysis of speech turn taking.
To assess speech turn taking during father-infant interaction, father and infant's
utterances were first segmented using ELAN. From the first 3 minutes free-play
recording, we obtained 9,706 segments of vocalization (duration varied from 0.1 to
7.79 seconds). Then infants and fathers utterances were labeled by two annotators
(blind to drug condition) as vocalization (including laugh, singing, and cry) or other
noise. For all items, the kappa values between the two annotators were between 0.82
and 1. From the annotation, we extracted all the speech turns of the infant and the
father using the algorithm specified in Delaherche et al. [2]. A speech turn is a
continuous stream of speech with less than 150-ms of silence. We obtained a list of
triples: speaker label (father or infant), start time, and duration of speech. From theses
triples, we also deduced the start time and duration of the time segments when the
father and/or the infant were not speaking (pauses). The following features of interest
were measured: Father Vocalization (the durations of the speaking segments for the
father); Infant Vocalization (the durations of the speaking segments for the infant);
Father Pause (silence >150 ms between consecutive father speech slots); Infant
Pause (silence >150 ms between consecutive infant speech slots). We also extracted
three features involving simultaneously both partners, i.e., synchrony variables: (1)
Silence (sequences of time during which none of the participant was speaking for
more than 150 ms). (2) Overlap Ratio (duration of vocalization overlapping between
father and infant divided by the duration of the total 3 minutes interaction); (3)
Synchrony Ratio (number of infant’s response to his father vocalization within a time
limit of 3 seconds divided by the number of father vocalisation during the time
paradigm). This feature estimated the ratio of timely related responses from the infant
following his/her father vocal features.
Supplement S4: Raw data of fathers' and infants' salivary oxytocin (OT) values in the
OT and placebo (PL) conditions.
Oxytocin
Father
Family
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
17
18
19
20
21
22
24
25
26
27
28
29
30
31
32
33
34
Baseline
30
12
13
14
31
24
18
68
21
18
34
56
15
31
9
12
14
29
22
13
9
17
11
22
34
27
54
19
25
13
10
10
Pre20 min
Interaction later
2477
617
72
370
4435
6801
30470
2477
21338
1190
2237
7973
20
465
645
529
209
203
627
800
70
3796
3796
30000
4000
2651
20306
30000
14195
452
18022
1190
1406
152
3931
118
6801
3055
18373
1517
231
2365
1886
5672
16
284
2660
257
270
60
498
1592
86
720
720
2651
111
1325
30000
2215
30467
204
44
13122
Placebo
Father
Infant
Pre40 min Interactio 20 min
n
later
later
40 min
Pre20 min
later Baseline Interaction later
787
161
44
108
104
1562
1065
973
188
452
413
2237
15
338
1293
54
148
36
324
2405
296
405
405
2107
80
592
953
4082
2000
169
127
1061
67
5982
129
65
5
3456
138
1474
478
888
15499
39949
77
5672
3456
5982
2477
605
1292
59
1564
1523
1592
82719
12113
409
408
1674
88
211
2215
13635
15
56
32
11
693
10
32
30
10
30
13
28
16
51
75
17
10
4
62
114
26
9
19
19
25
87
30
172
82
30
30
29
134
8227
35
56
32
35382
494
5793
4513
5032
39949
18373
36
4288
4082
8227
1867
764
1968
703
195
4617
5203
19578
34193
2938
8227
27300
2329
8227
3557
18022
14
19
20
11
18
20
34
26
16
31
4
37
17
21
13
8
15
20
18
20
8
14
27
34
36
22
20
38
23
62
18
6
15
25
38
17
55
12
18
43
25
21
20
258
34
51
15
12
11
9
20
122
21
17
28
65
44
29
18
22
44
22
28
4
8
22
31
24
28
12
28
31
16
32
7
156
12
25
14
11
12
10
26
23
12
16
30
356
18
16
33
49
18
25
16
14
Infant
Pre40 min Interactio 20 min
n
later
later
19
28
14
19
26
11
18
22
35
6
7
90
17
27
16
10
11
11
25
6
47
11
28
37
16
15
27
42
11
27
7
3
15
21
18
16
13
80
46
4
18
22
12
19
15
9
4
19
8
6
58
10
7
7
4
39
16
19
8
23
10
7
13
16
21
13
9
12
21
76
203
4
27
53
50
620
83
8
43
18
7
5
19
55
59
7
31
151
35
21
91
188
98
161
34
22
To assess whether infant’s OT increase was due to OT vs. Placebo condition or father
head acceleration or infant’s OT level before interaction, we computed a mixed
model. As shown in the table below, we only found a significant condition effect.
Value
(Intercept)
3.140779
Father OT treatment
4.310636
Father Acceleration Maximum 0.009582
OT Infant < Interaction
-0.003686
Std.Error
0.3809328
0.3803170
0.0062852
0.0027839
DF
t-value p-value
31 8.244969 0.0000
29 11.334324 0.0000
29 1.524519 0.1382
29 -1.323984 0.1958
This result means that there is no effect of maximum father’s acceleration when
considering the whole sample (PL + OT), there is only a group effect: the overall
level of infant's OT is significantly higher in the OT group than in the PL group
40 min
later
16
15
25
7
22
14
104
30
37
12
25
244
21
166
16
7
8
8
55
11
12
12
25
232
31
17
25
243
50
237
124
31
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2. Delaherche E., Chetouani M., Bigouret F., Xavier J., Plaza M. & Cohen D. 2013
Assessment of communicative and coordination skills of children with pervasive
developmental disorders and typically developing children using social signal
processing. Res. Aut. Spect. Dis. 7, 741-756.