The following section is separated into DATA and TOOLS. The former contains all the clean data that we conducted our analyses on, and the latter contains the code and other materials we used to conduct said analyses. **DATA:** The **Behavior** folder contains file "MeanACC_ExclusionDecision.xlsx" which lists all the participants, whether they finished the task, what ther mean accuracy percentage was, and based on those two criteria (finished task and accuracy higher than chance-level [>50%]), whether they should be excluded (label 1) or not (label 0). These data are shown before any exclusions (sheet MeanACC), after behavioral exlcusions (MeanACC_afterbeh) and after both behavioral and EEG exclusions (i.e., contain at least 200 trials after cleaning). Each of these sheets also represents the mean accuracy data as a histogram. Next, "BehAccPerStimulus_data.xlsx" contains the mean accuracy per participant for each of the conditions (visual, spatial, and verbal), as well as their age. The bottom rows of this sheet contain overall means and standard errors per condition for the whole sample, and also for the youngest participants (aged 7 - 8.5), and the difference between these youngest participants and the overall sample (named *accuracy drop*). The data are also represented visually, as a bar graph. Finally, "BehAccPerStimulus_data.jasp" contains the results of the statistical analysis comparing (openable in Jasp software: https://jasp-stats.org/download/). Next are two subfolders, where one contains only those datasets that have passed the above behavioral exclusion criteria (usable_afterBEHexclusion; 22 .csv files), and another that contains only those datasets that have passed both the behavioral and EEG exclusion criteria as above (usable_afterBEHandEEGexclusion; 20 .csv files). Note that mean accuracy results are displayed in R when running the "137_analysis" script. Each .csv file in the subfoldes contains the following information: - Participant: random participant number - Category: whether visual, spatial, or verbal - SameDiff: whether the Sensory and Probe stimulus were the same or different - Trigger_Sensory: trigger number at Sensory onset - Trigger_Delay: trigger number at Delay onset - Correct_response: what the participants should have pressed to get a correct response ("k" for same, "d" for different) - Actual_response: what participants actually pressed - Accuracy: correct (1) or incorrect (0) on that trial - RT: reaction time on that trial The **EEG** folder contains file "137_EEGcleaning.xlsx" detailing the cleaning process per participant. This includes the electrodes, trials, and components removed during cleaning, and the final decision on whether the dataset can be kept or not, for each participant. There is also file "ConditionTrialsPerPerson.csv" containing the numbers of trials per participant per condition (visual, spatial, and verbal) that went into the decoding. N.B., due to storage limits, the final clean EEG data are stored in the following Zenodo repository: https://zenodo.org/records/8425851 **TOOLS:** In the **Analysis** folder, you will find all the scripts used to analyze the behavioral and EEG data (planned decoding analyses and additional exploratory analyses of reliability and validity). For the behavioral analyses, there is "137_analysis.R" which gets the average accuracy scores and standard deviations before and after applying exclusion criteria, and "BehAccPerStimulus.R" which gets the accuracy scores per stimulus condition (visual, spatial, and verbal) and adds participant age. For the EEG analyses, the following scripts are to be used for given analyses, per the manuscript: Getting the number of trial per participant per condition, and the overall number of trials per condition: 1. GetTrialsPerCondition_part1.R 2. GetTrialsPerCondition_part2.R Time-average classification analyses + confusion matrices: 1. MVPA_Multiclass_timeAvg.m 2. GroupStatsPlots_timeAvg.m 3. SummaryStats_timeAvg.m Time-wise decoding analyses (theoretical chance) + temporal generalization analysis: 1. MVPA_Multiclass_timeWise.m 2. GroupStatsPlots_timeWise.m Split-half analyses: 1. MVPA_Multiclass_EarlyLate.m 2. GroupStatsPlots_EarlyLate.m 3. MVPA_Multiclass_Xdecode_EarlyLate.m 4. GroupStatsPlots_Xdecode_EarlyLate.m Individual differences analysis and regression of decoding accuracy by age: 1. MVPA_IndivDiff_RegressionByAge.m 2. GroupStatsPlots_IndivDiff_RegressionByAge.m Time-wise decoding analyses (empirical chance): 1. MVPA_ShuffledLabels.m 2. GroupStatsPlots_EmpiricChance.m In the **Cleaning** folder, you will find all the scripts used to preprocess the data and prepare them for analyses. Here, the Behavior folder contains the script used to conduct the exclusion check, and to organise the data into a neat, legible format ("137_dataprep.R"). The EEG folder contains the "preprocessing_137.m" script, which we used to clean the data. This script pulls EEG channel locations from "biosemi64.loc" and "137chanlocs.ced", and draws on "detectArtefacts.m" for the semi-automatic artefact rejection procedure. This folder also contains a step-by-step breakdown of how we cleaned the data in "Preprocessing_steps.docx", and a "Electrode_Numbers.xlsx" file translating electrode names in numeric (1-64) to A-B-EOG numeric (A1-B32 and EOG) to their names in the 10-20 system for easier electrode interpolation. In a separate component called Flux2022 poster, you can find the preliminary results of the study in the form of a poster (FLUX2022poster_v4.pdf), presented at the 2022 Flux congress in Berlin.