Early language outcomes in Argentinean toddlers: Associations with home literacy,screen exposure and joint media engagement

This study aimed to analyse the contribution of mothers' home literacy beliefs and practices and the quantity and quality of screen media exposure on Argentinean toddler's language. In addition, we considered parent–child joint engagement, as well as adult scaffolding behaviours during the use of electronic devices. A total of 465 mothers of 18–36 months old children completed an online survey including: the MacArthur Bates CDI, home literacy, screen exposure, joint engagement and scaffolding questionnaires. We observed positive effects of literacy beliefs, PC times and verbal scaffolding on language outcomes. TV exposure contributed negatively to vocabulary and, along with educational content, to sentence use. Shared reading and screen media experiences can be an opportunity for language stimulation, provided there is dialogue and joint engagement. Passive screen exposure and inadequate content may be detrimental for toddlers' language outcomes, probably by displacement of socially significant interactions.     

Familiarity and categorization processes in memory search

A fundamental distinction in tasks of memory search is whether items receive varied mappings (targets and distractors switch roles across trials) or consistent mappings (targets and distractors never switch roles). The type of mapping often produces markedly different performance patterns, but formal memory-based models that account quantitatively for detailed aspects of the results have not yet been developed and evaluated. Experiments were conducted to test a modern exemplar-retrieval model on its ability to account for memory-search performance involving a wide range of memory-set sizes in both varied-mapping (VM) and consistent-mapping (CM) probe-recognition tasks. The model formalized the idea that both familiarity-based and categorization-based processes operate. The model was required to fit detailed response-time (RT) distributions of individual, highly practiced subjects. A key manipulation involved the repetition of negative probes across trials. This manipulation produced a dramatic dissociation: False-alarm rates increased and correct-rejection RTs got longer in VM, but not in CM. The qualitative pattern of results and modeling analyses provided evidence for a strong form of categorization-based processing in CM, in which observers made use of the membership of negative probes in the “new” category to make old–new recognition decisions.