Measuring rhythms of vocal interactions: a proof of principle in harbour seal pups.

Rhythmic patterns in interactive contexts characterize human behaviours such as conversational turn-taking. These timed patterns are also present in other animals, and often described as rhythm. Understanding fine-grained temporal adjustments in interaction requires complementary quantitative methodologies. Here, we showcase how vocal interactive rhythmicity in a non-human animal can be quantified using a multi-method approach. We record vocal interactions in harbour seal pups (Phoca vitulina) under controlled conditions. We analyse these data by combining analytical approaches, namely categorical rhythm analysis, circular statistics and time series analyses. We test whether pups' vocal rhythmicity varies across behavioural contexts depending on the absence or presence of a calling partner. Four research questions illustrate which analytical approaches are complementary versus orthogonal. For our data, circular statistics and categorical rhythms suggest that a calling partner affects a pup's call timing. Granger causality suggests that pups predictively adjust their call timing when interacting with a real partner. Lastly, the ADaptation and Anticipation Model estimates statistical parameters for a potential mechanism of temporal adaptation and anticipation. Our analytical complementary approach constitutes a proof of concept; it shows feasibility in applying typically unrelated techniques to seals to quantify vocal rhythmic interactivity across behavioural contexts. This article is part of a discussion meeting issue 'Face2face: advancing the science of social interaction'.

Effect of pseudoephedrine on 800-m-run times of female collegiate track athletes.

CONTEXT: Pseudoephedrine (PSE) is an over-the-counter decongestant that might have ergogenic effects. The World Anti-Doping Agency has prohibited large doses (>150 µg/mL) of PSE, while the National College Athletic Association (NCAA) does not include it on their banned-substance list. PURPOSE: This study examined the effect of body-weight dosing of PSE on 800-m-run times of NCAA female runners. METHODS: Fifteen NCAA female track athletes volunteered to participate in the randomized, double-blind, crossover design. Participants were given 2.5 mg/kg PSE or placebo in trials separated by a week. Ninety minutes postingestion, participants completed an 800-m individual time trial on an indoor track. Finishing time was recorded with an automated video timing device. Heart rate and anxiety state scores were recorded immediately after each trial. RESULTS: Fourteen runners completed both trials, and 1 was an outlier: N=13. Despite the dose being well above normal therapeutic levels (144±17 mg), there was no significant difference (P=.92) in 800-m times between PSE (2:39.447±9.584) and placebo (2:39.372±9.636) trials, in postexercise heart rate (P=.635; PSE=177.9±14.5 beats/min, placebo=178.4±18.5 beats/min), or in anxiety-state levels (P=.650; PSE=38.4±11.6, placebo=38.1±8.8). CONCLUSION: A 2.5-mg/kg dose of PSE had no effect on 800-m performance for female NCAA runners. More research is needed to determine if PSE should be a specified banned substance.