Table 1
Basic demographic characteristics of participants in Study 1, by randomised condition. Participants were randomly assigned to one of the two emotional context conditions (“Soothe the baby” – on each trial participants were shown a crying baby face – or “Keep the baby happy” – on each trial participants were shown a happy baby face).
| CHARACTERISTIC | ‘SOOTHE THE BABY’ N = 103 | ‘KEEP THE BABY HAPPY’ N = 100 |
|---|---|---|
| Age | 19.70 (2.43) | 19.88 (2.89) |
| Ethnicity | ||
| White or Caucasian | 83 (81%) | 82 (83%) |
| Asian or Asian American | 14 (14%) | 9 (9.1%) |
| Other ethnicity | 6 (5.8%) | 8 (8.1%) |
| Gender | ||
| Girl | 90 (87%) | 82 (83%) |
| Boy | 12 (12%) | 17 (17%) |
| Prefer not to say | 1 (1.0%) | 0 (0%) |
| Highest Education | ||
| Below undergraduate | 8 (7.8%) | 3 (3.0%) |
| Undergraduate or higher | 95 (92%) | 97 (97%) |
| Income | ||
| Under £15,000 | 9 (11%) | 11 (13%) |
| £15,000–£29,999 | 19 (22%) | 17 (21%) |
| £30,000–£49,999 | 17 (20%) | 14 (17%) |
| £50,000–£74,999 | 14 (16%) | 15 (18%) |
| £75,000–£99,999 | 8 (9.4%) | 11 (13%) |
| Over £100,000 | 18 (22%) | 14 (17%) |
| Age of Menarche | ||
| 9–10 years | 9 (10%) | 6 (7.3%) |
| 11–12 years | 40 (44%) | 33 (40%) |
| 13–14 years | 34 (38%) | 35 (43%) |
| 15+ years | 7 (7.8%) | 8 (9.8%) |
| Hormonal Contraceptive | ||
| Yes | 49 (54%) | 44 (54%) |
| No | 41 (46%) | 38 (46%) |
[i] Note. Other ethnicity includes Black, Hispanic, and other groups. Education categories were combined into ‘Below undergraduate’ and ‘Undergraduate or higher’ due to small sample sizes. Income categories over £100,000 were merged into ‘Over £100,000’.
Figure 1
Participant recruitment, allocation and attrition/removal in Study 1 and Study 2.
Note. This figure was created in BioRender. Costantini, I. (2025) https://BioRender.com/7ppxkl9.
Figure 2
Maternally adapted version of a two-arms bandit task.
Note. Timeline of events within a trial. Feedback can be a sad, neutral or happy baby face. a) “Soothe the baby” condition (with a positive outcome); b) “Keep the baby happy” condition (with a neutral outcome).
Table 2
Demographic characteristics of participants included in the analyses in Study 1 (nulliparous female and male student participants) and Study 2 (ALSPAC pregnant women).
| DEMOGRAPHICS | STUDY 1: STUDENT | STUDY 2: ALSPAC | ||
|---|---|---|---|---|
| VARIABLES | N | MEAN (SD)/% | N | MEAN (SD)/% |
| Age | 191 | 19.82 (2.73) | 109 | 29.11 (1.51) |
| Gender/Sex | ||||
| Male | 28 | 14.66% | 0 | 0% |
| Female | 161 | 84.29% | 109 | 100% |
| Other | 2 | 1.04% | – | – |
| Education | ||||
| A Level or Higher | 180 | 94.2% | 39 | 43.33% |
| O Level | – | – | 37 | 41.11% |
| <O Level | – | – | 14 | 15.56% |
| High-school diploma (=GCSE) | 11 | 5.8% | – | – |
| Performance task | ||||
| In person | 191 | 100% | 25 | 22.9% |
| Online | 0 | 0% | 84 | 77.1% |
| MENTAL HEALTH MEASURES | N | MEDIAN (IQR) | N | MEDIAN (IQR) |
| Depression score | ||||
| SMFQ | 190 | 7 (4–10) | – | – |
| EPDS | – | – | 80 | 13 (9.5–15) |
| Anxiety | ||||
| STAI-I | 190 | 38 (32–46) | – | – |
| STAI-II | 190 | 46 (39–53) | – | – |
| Personality difficulties | ||||
| SAPAS | 190 | 3 (2–4) | 91 | 2 (1–3) |
| BIS-11 | 190 | 64 (58–69) | 29 | 51 (49–59) |
[i] Note. IQR: Inter-quartile Intervals; ALSPAC: Avon Longitudinal Study of Parents and Children; SAPAS: Standardized Assessment of Personality Abbreviated Scale; MFQ: Mood and Feeling Questionnaire; EPDS: Edinburgh Post-Natal Depressive Scale; STAI: State-Trait Anxiety Inventory; BIS: Barrett Impulsivity Scale.
Figure 3
Effect of the baseline emotional state on the parameters of the reference model (Study 1).
Note. The top two graphs and the bottom left graph illustrate the posterior differences for the population level means between the two conditions. The 95% highest density intervals are marked with the horizontal red line at the base of the histogram bars. The bottom right graph shows the median and 95% credible (highest density) intervals of the posterior densities for the population level mean learning rate, reference point, and inverse temperature.
Table 3
This table illustrates whether the context manipulation affected the post-test rating scores on both the emotions’ and temperament’ ratings.
| RATING EMOTION | N | POSTERIOR MEAN DIFFERENCE (95% CrIs) | Rhat |
|---|---|---|---|
| Negative | 203 | 0.02 (–2.84 to 2.85) | 1 |
| Neutral | 203 | –0.88 (–3.55 to 1.72) | 1 |
| Happy | 203 | 0.39 (–1.67 to 2.49) | 1 |
| RATING TEMPERAMENT | N | POSTERIOR MEAN DIFFERENCE (95% CrIs) | Rhat |
| Negative | 203 | 0.86 (–4.49 to 6.44) | 1 |
| Neutral | 203 | –1.41 (–6.49 to 3.53) | 1 |
| Happy | 203 | 4.39 (0.14 to 8.78) | 1 |
[i] Note. The table reports brms estimates on the final rating score on both emotions and temperament with the condition. The reference condition is the “Soothe the baby”. 95% CrIs: Credible Intervals. Rhat is a convergence diagnostic statistic used in Markov Chain Monte Carlo (MCMC) models. An Rhat value below 1.05 is generally considered a strong indication that the chains have converged well.
Table 4
This table reports the posterior median effect size and 95% CrI representing the association between levels of personality difficulties, depression, anxiety and impulsivity and the parameters of interest in both Study 1 and Study 2.
| MENTAL HEALTH MEASURE1 | PARAMETERS2 | STUDY 1 (NULLIPAROUS PARTICIPANTS) | STUDY 2 (ALSPAC PARTICIPANTS) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| NUMBER OF PARTICIPANTS | ESTIMATE (MEDIAN POSTERIOR DISTRIBUTION) | 95% CRI | RHAT | NUMBER OF PARTICIPANTS | ESTIMATE (MEDIAN POSTERIOR DISTRIBUTION) | 95% CRI | RHAT | ||
| Alpha | |||||||||
| Personality difficulties (SAPAS) | 190 | –0.08 | –0.20 to 0.04 | 1.00 | 91 | –0.18 | –0.30 to –0.04 | 1.00 | |
| Depressive symptoms (MFQ in Study 1 and EPDS in Study 2) | 190 | –0.06 | –0.17 to 0.06 | 1.00 | 80 | –0.14 | –0.30 to 0.01 | 1.00 | |
| Depressive symptoms (EPDS without anxiety items) | – | – | – | 80 | –0.14 | –0.30 to 0.03 | 1.00 | ||
| State anxiety (STAI-Y1) | 190 | –0.03 | –0.13 to 0.08 | 1.00 | – | – | – | – | |
| Trait anxiety (STAI-Y2) | 190 | –0.06 | –0.18 to 0.05 | 1.00 | – | – | – | – | |
| Impulsivity (BIS-11) | 190 | –0.08 | –0.19 to 0.03 | 1.00 | – | – | – | – | |
| Tau | |||||||||
| Personality difficulties (SAPAS) | 190 | –0.03 | –0.08 to 0.02 | 1.00 | 91 | 0.01 | –0.08 to 0.10 | 1.00 | |
| Depressive symptoms (MFQ in Study 1 and EPDS in Study 2) | 190 | 0.00 | –0.07 to 0.08 | 1.00 | 80 | –0.07 | –0.15 to 0.02 | 1.00 | |
| Depressive symptoms (EPDS without anxiety items) | – | – | – | – | 80 | –0.06 | –0.15 to 0.02 | 1.00 | |
| State anxiety (STAI-Y1) | 190 | –0.05 | –0.10 to –0.00 | 1.00 | – | – | – | – | |
| Trait anxiety (STAI-Y2) | 190 | –0.00 | –0.05 to 0.05 | 1.00 | – | – | – | – | |
| Impulsivity (BIS-11) | 190 | –0.02 | –0.08 to 0.02 | 1.00 | – | – | – | – | |
| Eta | |||||||||
| Personality difficulties (SAPAS) | 190 | 0.07 | –0.01 to 0.14 | 1.00 | 91 | –0.02 | –0.12 to 0.07 | 1.00 | |
| Depressive symptoms (MFQ in Study 1 and EPDS in Study 2) | 190 | –0.00 | –0.06 to 0.05 | 1.00 | 80 | 0.02 | –0.07 to 0.11 | 1.00 | |
| Depressive symptoms (EPDS without anxiety items) | – | – | – | – | 80 | 0.01 | –0.08 to 0.10 | 1.00 | |
| State anxiety (STAI-Y1) | 190 | 0.04 | –0.03 to 0.11 | 1.00 | – | – | – | – | |
| Trait anxiety (STAI-Y2) | 190 | 0.01 | –0.06 to 0.08 | 1.00 | – | – | – | – | |
| Impulsivity (BIS-11) | 190 | –0.07 | –0.14 to –0.01 | 1.00 | – | – | – | – | |
[i] Note. CrI: Credible Intervals; ALSPAC: Avon Longitudinal Study of Parents And Children; SAPAS: Standardized Assessment of Personality Abbreviated Scale; MFQ: Mood and Feeling Questionnaire; EPDS: Edinburgh Post-Natal Depressive Scale; STAI: State-Trait Anxiety Inventory; BIS: Barrett Impulsivity Scale. Rhat is a convergence diagnostic statistic used in Markov Chain Monte Carlo (MCMC) models. An Rhat value below 1.05 is generally considered a strong indication that the chains have converged well.