11  Procedure

Please adhere to the following specifications for conducting this study. If any of the following technical specifications are not possible for your lab, please contact the MB5 leadership team (mb5@manybabies.org) before beginning data collection to inform us of your planned deviation and the reason for it.

11.1 Overview

During the experiment, infants will be seated on their caregiver’s lap or in a high-chair or car seat (whichever option corresponds to a lab’s standard procedure for testing infants, as reported in the pre-data-collection survey).

Important

PUT IN GRAPHIC SHOWING ROOM CONFIG

Each baby will be presented with a series of 12 trials. Each trial is preceded by an attention-getter and made up of a familiarization phase followed by the test phase (see Figure 11.1).

There are two versions of the experiment:1

  1. Fixed-length, in which the duration of the familiarization phase is pre-established (5s, 10s or 15s)
  2. Infant-controlled, in which the familiarization phase lasts until the infant accumulates the specified looking time (5s, 10s, or 15s). In both versions, the duration of each test phase is fixed at 5s.

1 Participating labs are encouraged to use an infant-controlled procedure, if possible. See Section 11.3 for more info.

Trial schematic:

Figure 11.1: This figure depicts the design of an example trial. At familiarization, a single image is shown for 5, 10, or 15s. After the specified familiarization time is reached (based on the infant-controlled or fixed-length design criteria), infants are presented with a central fixation stimulus for 500ms. During the two test periods (5s each), infants view the same image to which they were familiarized paired with a new stimulus from the same set (e.g., Fribbuli or Fractals) and the same level of complexity (low or high). The side on which the familiar and novel images are presented is counterbalanced across test phases within a trial, but the images remain the same.

11.2 Trial initiation

This phase draws infants’ attention (back) to the screen prior to the familiarization using the “laughing baby” stimulus. The trial is initiated when the infant fixates the screen (or a maximum of 10s has elapsed).

11.3 Familiarization Phase

In the familiarization phase, one stimulus is presented centrally on the screen. There are a total of 12 familiarization events for each infant that vary across three dimensions (see Table 11.1):

  1. Stimulus class (Fribbuli or Fractals)
  2. Complexity level (low or high); and
  3. Familiarization time (5s, 10s, or 15s)2

2 Familiarization time specifies the duration of the familiarization phase (fixed-length design), or the duration of accumulated looking time needed to end the familiarization phase (infant-controlled design).

The order of these trials will be counterbalanced along a number of dimensions across participants and labs.

Table 11.1: Familarization events (Note: Order of events will be counterbalanced across pariticipants)
Event Familiarization Time (s) Stimulus Class Complexity Level Example Stimulus
1
2
3		 5
10
15
Fribbuli
Low
4
5
6		 5
10
15
Fribbuli
High
7
8
9		 5
10
15
Fractals
Low
10
11
12		 5
10
15
Fractals
High

Infant-Controlled Familiarization

If your lab is running the infant-controlled version of the study, infants may accumulate the required familiarization time across multiple looks before advancing to the test phase. The familiarization stimulus will remain on the screen until the infant has looked at the stimulus for the specified duration (as determined by an experimenter coding infant looking in real time).

We will additionally implement a maximum trial length criterion: if infants do not accumulate the required looking time within twice the specified familiarization duration (i.e., 10, 20, or 30s), the familiarization phase will end.

Fixed-Length Familiarization

If your lab is unable to run an infant-controlled design, then you will present the familiarization stimulus for a specified duration (5, 10, or 20s) before advancing to the test phases.

11.4 Test Phase

Once the familiarization criterion has been reached (either via accumulated looking or fixed-length presentation), the infant will be presented with a central-fixation stimulus (looming circle). Once the infant fixates the screen (or a maximum of 5s has elapsed), the test phase will begin.

The test phase is made up of two 5s test periods. In each test period, the object seen during familiarization (the familiar object) is presented side-by-side with a previously-unseen novel object.3 The location (left/right) of the familiar and novel stimuli will be switched in the two test periods (e.g., if the familiar object appears on the left in the first test period, it will appear on the right in the second test period). A central fixation attention-getting stimulus (looming circle) will be presented on the screen between the first and second test periods.4

3 The novel object on each trial will be from the same stimulus class (Fribbuli or Fractals) and complexity level (low or high) as the familiar object.

4 The attention-getter between test periods will be presented for either 750ms (Fixed-length procedure) or until the infant looks at the attention-getter for 500ms (Infant-controlled procedure)