Abstract

The aim of this study was to determine if processing speed, measured as visual reaction time (RT), of 10 month-olds obtained through an IPLP (Intermodal Preferential Looking Paradigm) in a word learning task, can be an indicator of communicative abilities such as productive vocabulary, during the second year of life. Participants were 13 infants of 9-12 months of age (X=10.15) at the beginning of the study, whose native language was Spanish and without visual or auditory problems reported by parents. The same group of infants was evaluated when they were between 24 and 30 months of age. Infants’ RTs were obtained at the age of 10 months in a word learning task, and related to communicative abilities measured with the Inventario de Habilidades Comunicativas MacArthur Versión II (CDI-II) when the infants were between 24 and 30 months of age (X=27.10). A linear regression analysis was performed using the RT from the experimental task as a predictor and the CDI-II vocabulary score as dependent variable. It was found that RT measured at 10 months of age can be used as a predictor of the vocabulary size in the same infants 18 months later. The results presented here imply that infants who take longer in processing a novel object associated with a novel word, are the ones who will have more words in their productive vocabulary during the second year of life, as reported by parents. The measures of processing speed in this study, demonstrates the length of time it takes a child to process non-familiar information in real time. The results obtained, support the study of processing speed at early ages in tasks that measure cognitive abilities other than word recognition. It suggests taking into account the analysis of individual differences, either processing speed or vocabulary, to better understand the relationship between these two variables in the first years of life. Furthermore, the results obtained in this paper highlight the importance of the study of RT in early ages and give information about the effects of slower or faster information processing over different linguistic abilities in infants.