In addition, participants indicated how often they combined each of these activities with another one. To separate the extent of multitasking from the amount of consumption of media, the authors computed a Media-Multitasking Index
(MMI) that ranged from 0 (all media consumed singly) to 12 (all media consumed simultaneously with all other media) but was unaffected by the total amount consumed. For example, a child who played video games 40 hours a week but did nothing else at the same time (except perhaps the occasional glance at the homework) might still have a low MMI.
Participants reported consuming a great deal of media, with the TV (surprisingly?) still being the primary channel of consumption. The MMI scores averaged out to around 3.0, representing 25% concurrent media usage. However, the distribution had a positive skew, with a fairly fat upper tail extending into the 50% region and beyond.
In order to examine how media multitasking affects cognitive performance, Cain and colleagues also obtained indicators of academic performance (namely, Math and English Language Arts scores maintained by the Massachusetts Department of Elementary and Secondary Education) and tested participants on various cognitive tasks and attributes, such as their working memory and cognitive processing speed, their manual dexterity and vocabulary. In addition, participants’ levels of “grit” (i.e., their ability to persevere in difficult or even impossible tasks), conscientiousness and impulsiveness were also tested.
The results were discouraging for multi-media users and confirming the single-channel parents’ intuitions: In a nutshell, the more students multi-tasked outside of school, the worse they fared on both components of their test scores (math and English language arts). This effect was of medium size
, with a correlation coefficient of -.3, implying that just under 10% of the total variance in students’ scores was accounted for by their multi-media index (MMI).
Of course, this relationship might be due to a variety of factors and the direction of causality is unclear. For example, poor students might be so disappointed by their performance at school that they resort to more media for gratification, or there might be yet another variable explaining the association.
To narrow down these possibilities, Cain and colleagues explored how performance on the various cognitive tasks related to the MMI.
Cain and colleagues found that the MMI was negatively associated with two measures of working memory, acounting span
and an N-back task
. By contrast, several measures of crystallized intelligence
, namely vocabulary, comprehension and calculation performance, were not
associated with the MMI. The selectivity of those associations suggests that multi-media use does not impair cognition generally, but it may have an adverse impact on those tasks that require attentional and executive control.
This interpretation was supported by the further fact the MMI was associated with impulsivity, that is children’s tendency to act on a whim, displaying behavior characterized by little or no forethought, reflection, or consideration of the consequences
. None of the other personality attributes considered (e.g., grit or conscientiousness) were associated with multi-media use, again suggesting that the effect of media multi-tasking is quite selective.
In summary, the results of Cain and colleagues suggest that only tasks and behavioral attributes that involve attentional control are negatively associated with multi-media use. Notably, those associations arise at a young age, before adulthood, and they can be picked up in “real life” measures that matter a great deal to a person’s life—namely their scholastic performance.
What are the practical implications of those results?
At first glance, as a parent one might be tempted to regulate the amount of time that one’s teenagers spend watching television while also playing video games or using their phones. However, even setting aside the obvious difficulties of actually doing this, such attempts at regulation might be premature: As one of the authors, Amy Finn, put it: “The direction of causality is difficult to establish. For example, media multitasking may be a consequence of underlying cognitive differences and not vice versa.” Even though the specificity of the associations is compatible with a causal interpretation, the data do not permit any unambiguous inference for now.
Article focused on in this post:
Cain, M.S. et al. (2016). Media multitasking in adolescence. Psychonomic Bulletin & Review