Last year, a study was published providing validation for smartphones as a useful tool for data collection in cognitive science . This year, Apple unveiled a set of technologies called ResearchKit that allow developers access to data from an iPhone???s health monitoring functions .
This project would involve implementing an application that takes health data from a smartphone and cross-references it with psychological metrics. A fairly straightforward example of this concept would be to take an existing metric tool e.g. ???Track Your Happiness??? , and re-creating it while also tracking physical activity to see if a link could be established.
I would have a preference for working with iOS development to take advantage of the new ResearchKit, but I would not rule out developing an Android application.
 Crowdsourcing for Cognitive Science - The Utility of Smartphones http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0100662  Apple.com: ResearchKit https://www.apple.com/researchkit/  Track your Happiness https://www.trackyourhappiness.org/