Evidence against benefits from cognitive training and transcranial direct current stimulation in healthy older adults.

Cognitive training and brain stimulation show promise for ameliorating age-related neurocognitive decline. However, evidence for this is controversial. In a Registered Report, we investigated the effects of these interventions, where 133 older adults were allocated to four groups (left prefrontal cortex anodal transcranial direct current stimulation (tDCS) with decision-making training, and three control groups) and trained over 5 days. They completed a task/questionnaire battery pre- and post-training, and at 1- and 3-month follow-ups. COMT and BDNF Val/Met polymorphisms were also assessed. Contrary to work in younger adults, there was evidence against tDCS-induced training enhancement on the decision-making task. Moreover, there was evidence against transfer of training gains to untrained tasks or everyday function measures at any post-intervention time points. As indicated by exploratory work, individual differences may have influenced outcomes. But, overall, the current decision-making training and tDCS protocol appears unlikely to lead to benefits for older adults.

Task instructions and implicit theory of mind.

It has been hypothesized that humans are able to track other's mental states efficiently and without being conscious of doing so using their implicit theory of mind (iToM) system. However, while iToM appears to operate unconsciously recent work suggests it does draw on executive attentional resources (Schneider, Lam, Bayliss, & Dux, 2012) bringing into question whether iToM is engaged efficiently. Here, we examined other aspects relating to automatic processing: The extent to which the operation of iToM is controllable and how it is influenced by behavioral intentions. This was implemented by assessing how task instructions affect eye-movement patterns in a Sally-Anne false-belief task. One group of subjects was given no task instructions (No Instructions), another overtly judged the location of a ball a protagonist interacted with (Ball Tracking) and a third indicated the location consistent with the actor's belief about the ball's location (Belief Tracking). Despite different task goals, all groups' eye-movement patterns were consistent with belief analysis, and the No Instructions and Ball Tracking groups reported no explicit mentalizing when debriefed. These findings represent definitive evidence that humans implicitly track the belief states of others in an uncontrollable and unintentional manner.