Abstract
Exposure to multiple versus a single speaker is known to improve learning of a new
phonological variant, presumably because of the greater variability it contains (Bradlow &
Bent 2008; Lively, Logan & Pisoni, 1993; Rost & McMurray, 2009). Here we test whether
having a larger social network, defined here as the number of people one regularly talks to,
similarly improves phonological skills in adults' native language. Furthermore, we examine
which phonological skills are improved in order to better understand how variability boosts
phonological skills.
To test whether having a larger social network improves phonological skills, 60 participants
logged in information about their conversations for one typical week. We then calculated for
each participant the number of people they talk to, as well as the number of hours they talk,
to distinguish between the effects of amount of input and number of sources for the input.
Participants were then invited to the lab for phonological and cognitive tests. To test whether
having a larger social network improves the robustness of phonological representations,
participants transcribed nonwords presented in noise. To test whether having a larger social
network improves the ability to identify and isolate voices, participants followed instructions
from one of two talkers talking simultaneously (Coordinate Response Measure; Johnsrude et
al., 2013). Lastly, to test the effect on talker normalization, and in particular, the efficiency of
switching between speakers, we measured the degree to which performance slowed down
in multi-speaker compared to the single-speaker blocks in a phoneme monitoring task.
Additionally, to ensure that effects of social network size are not due to cognitive differences
between people who interact with few versus many people, participants' WM, Auditory Short
Term Memory, selective attention, and task switching abilities were measured.
Results revealed that social network size does not correlate with any of the cognitive
measures (all r's<|0.08|). Social network size also did not correlate with amount of input
(r=0.13). This indicates that any effect of social network size cannot be due to cognitive
differences or amount of input. Nevertheless, to be conservative, we entered performance
on the cognitive tasks and amount of input as correlates into the mixed model analysis.
Results showed that participants with larger social networks are better at perception of
speech in noise. Results did not show any improvement in talker isolation or normalization.
Additionally, better Auditory STM predicted better perception of speech in noise, and higher
WM predicted better talker normalization.
To conclude, this study shows that individuals who regularly talk to more people have more
robust phonological representations, as reflected by better perception of speech in noise.
This suggests that variability in input can boost phonological skills even in one's native
language. While we cannot rule out completely non-causal explanations of the effect, we do
show that in the real world, people with larger social networks have more robust
phonological skills, and that this difference is not due to differences in cognitive abilities. This
shows that people's life-style can influence their linguistic abilities. Other studies we are
currently conducting show that this is true for other linguistic levels as well (e.g., semantic).
