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.     

Problems in Psychiatric Genetic Research: A Reply to Faraone and Biederman

This article examines evidence cited in favor of the operation of genetic factors in attention-deficit hyperactivity disorder (ADHD). Like other psychiatric conditions, a belief in the genetic basis of ADHD is derived from the results of family, twin, and adoption studies. Because family studies are widely believed to be confounded by environmental factors, primary emphasis is placed on twin and adoption studies. ADHD twin studies depend on the validity of the equal environment assumption (EEA), which holds that the environments of identical (MZ) and fraternal (DZ) twins are the same. Here it is argued that however the EEA is defined, it cannot be accepted. Therefore, the greater similarity or concordance of MZ twins when compared to DZ twins is plausibly explained by environmental factors. Adoption studies constitute a third method for investigating the role of genetic factors in ADHD. It is argued that these studies are greatly flawed by factors including non blinded diagnoses and the failure to study the biological relatives of adoptees. After an examination of the total weight of evidence in favor of a genetic basis or predisposition for ADHD, it is concluded that a role for genetic factors is not supported and that future research should be directed toward psychosocial causes