Two files are available as a result of data extraction from the 51 studies included in the systematic review entitled: "Early triadic interactions in the first year of life: A systematic review on object-mediated shared encounters": (1) DataExtraction.csv -> Dataset resulting from data extraction. (2) DictionaryVariables.csv -> dictionary of the variables included in the dataset: Authors, doi, Year of publication, Study type, Design type, Data analysis strategy, Type of task, Objects, Infants' age (months), Context of interaction, and Country.

This study was supported by the Predoctoral Contract Scholarship for PhD Training (call 2020), granted to the first author [reference PRE2020-094773], and by project PID2019-108845GA-I00/AEI/10.13039/501100011033, both co-funded by the State Research Agency (Ministry of Science and Innovation, Spain) and the European Social Fund (ESF).