Does being bilingual give people a cognitive advantage? According to published research, it does. In fact, I've summarized one such study on this blog. However, the website for the Association for Psychological Science (APS) has summarized a recent review of this research. The review starts with the research that has been published on this question:
Many published studies have shown that bilingual speakers perform better on cognitive tasks related to executive function abilities — such as those involved with attention and the ability to ignore distractions and switch between tasks — when compared to people who are fluent in only one language.
But what about the research that hasn't been published? Does the unpublished research on bilingualism show pretty much the same pattern? Or is there a file drawer problem (see Ch 14, p. 422), in which research that shows no effect of bilingualisim on cognitive abilities is less likely to be published? Here's the APS summary:
.... in informal discussions with colleagues, [researcher] de Bruin and her co-authors confirmed that study results that fail to support the bilingual advantage often don’t make it to publication. Thus, they never become part of the established scientific literature — a phenomenon known as the “file drawer effect.”
For a researcher interested in this question, the challenge in estimating the "file drawer effect" is in locating studies that have not been published. How would you find such studies? You can't locate them in journals, and they won't be searchable in the PsycINFO database. To address this problem, a new summary of the research on bilingualism and cognition took this approach:
the researchers decided to compare studies presented at conferences with those that are eventually published. They identified 104 conference abstracts describing studies on bilingualism and executive control in any age group, presented between 1999 and 2012. They then looked to see which of those studies were accepted for publication in an international scientific journal on or before February 2014.
What did they find?
The researchers found that the majority (63%) of the studies that supported the bilingual advantage, either partly or completely, were published; however, only 36% of the studies that mainly or fully failed to support the advantage were published.
The difference in publication rates couldn’t be explained by the specific tasks or the sample sizes used in the studies.
A take-home message from this new summary is that
these findings underscore how essential it is to review the published scientific literature with a critical eye, and how important it is that researchers share all of their findings on a given topic, regardless of the outcome.
a) How is the issue of publication bias related to the issue, raised in Chapter 14, of Replications by Independent Researchers?
b) Why is it important for scientists to find research that has been completed, but not published?
c) Can you think of other creative ways to locate studies that have been completed, but not published?