'Interoceptive sensitivity at 3 months of age' (AsPredicted #108121)
Author(s) This pre-registration is currently anonymous to enable blind peer-review. It has 3 authors.
Pre-registered on 2022/09/28 - 05:22 AM (PT)
1) Have any data been collected for this study already? It's complicated. We have already collected some data but explain in Question 8 why readers may consider this a valid pre-registration nevertheless.
2) What's the main question being asked or hypothesis being tested in this study? Our main research question is whether 3-month-old infants display cardiac and respiratory interoceptive sensitivity. We expect that infants can discriminate between stimuli presented synchronous and asynchronous to their physiological signal in both domains.
We will also investigate whether both domains are related in this age group. We do not expect that both domains are related.
Moreover, we will investigate whether mothers' interoceptive skills are related to their infants' interoceptive skills. We expect that maternal interoceptive accuracy shows a positive relationship- and maternal interoceptive attention a negative relationship with the infant's interoceptive sensitivity in both domains, respectively.
3) Describe the key dependent variable(s) specifying how they will be measured. To measure infants' cardiac interoceptive sensitivity, we will use the iBEATs task in which infants are presented with stimuli that pulsate either synchronously or asynchronously with their own heartbeat (Maister et al. 2017).
To measure respiratory interoceptive sensitivity, we developed the iBREATH task in which infants are presented with stimuli that expand or decrease either synchronously or asynchronously with their respiration.
We will calculate a discrimination score as the absolute proportion of the difference between looking times in the synchronous and asynchronous trials separately for cardiac and respiratory interoception tasks to later correlate the two measures (Maister et al. 2017).
Between both tasks we will include a resting state task in which we measure the infants' ECG for 2 minutes while we show a neutral video.
We will measure the mothers' interoception using the Interoceptive Accuracy- and Interoceptive Attention Scales. Further, mothers will complete a heartbeat counting- (four trials – 25s, 35s, 45, 75s) and a time counting task (four trials – 28s, 38s, 48s, 68s). After each trial in the heartbeat counting task mothers will be asked to indicate how confident they are that their answer was correct. We will use adapted instructions and compute heartbeat counting-, confidence-, and time counting scores (Desmedt et al. 2020). We will classify the Interoceptive Attention Scale as measuring interoceptive attention. We will classify the Interoceptive Accuracy Scale and the heartbeat counting task scores as indices of interoceptive accuracy.
4) How many and which conditions will participants be assigned to? In a within participants design, infants will do both tasks in a randomized order. Mothers will be sent a link with the questionnaires after the testings. The heartbeat counting task will be done either after the infants' testing or in breaks arising from the infant needing a rest/sleep.
In both iBEATs and iBREATH tasks, we will use a Eyelink 1000plus to record looking times at 500Hz. In both tasks a trial will be terminated, and the next trial starts, if after the initial 5s no looking times were recorded for 2s. A task will be terminated if 80 trials are reached, or if the infant either becomes fuzzy/tired, or no looking times to extend the task beyond 5s was recorded in 5 successive trials. For each trial, we will extract and aggregate looking times falling into the range of the animated figures.
5) Specify exactly which analyses you will conduct to examine the main question/hypothesis. For iBEATs and iBREATH tasks, we will conduct Bayesian paired t-tests to investigate whether there is evidence for a mean group difference between synchronous and asynchronous conditions.
To investigate whether performance on both tasks is related, we will compute Pearson correlations between the iBEATs and iBREATH scores.
To investigate whether the mothers' interoception is related to the infants' interoception, we will assess Pearson correlations between IAS, IATS, heartbeat counting scores, and confidence ratings with infants' individual difference scores. Next, we will compare whether the correlation coefficient significantly differ from each other. To prevent multiple comparison issues, we will compute a chi-square test on Fisher z-transformed correlation coefficients and will follow up with planned comparisons in case of a significant result.
All null-hypothesis tests will be against p < .05. In case assumptions for parametric approaches are violated, we will use non-parametric equivalents.
6) Describe exactly how outliers will be defined and handled, and your precise rule(s) for excluding observations. For iBEATs and iBREATH, we will include infants who completed at least four trials in the main analysis. We will exclude trials with looking times of 0. Further, for both iBEATs and iBREATH, we will exclude trials with artifacts in the physiological signal. In the iBEATs task, we will exclude trials in which the ECG built in function (AdInstruments, FastResponseOutput) recognized at least 85% of the R-Peaks in a trial. In the iBREATH task, we will exclude trials which have extended periods of artifacts, so that no respiration like signal is observable.
For the heartbeat counting task, we will exclude trials with ECG artifacts that make identification of the R-peaks impossible.
7) How many observations will be collected or what will determine sample size? No need to justify decision, but be precise about exactly how the number will be determined. We aim to test 80 participants. In case we do not reach this aim until August 2023, we will terminate the data collection.
8) Anything else you would like to pre-register? (e.g., secondary analyses, variables collected for exploratory purposes, unusual analyses planned?) We have already tested 5 participants. However, we did not process any data yet.
