The synchrony effect revisited: chronotype, time of day and cognitive performance in a semantic analogy task

ABSTRACT

The synchrony effect (i.e. superior performance at optimal, inferior performance at suboptimal times of day) has been broadly studied within the context of circadian rhythms. Whether one chronotype copes better with the synchrony effect than the other received only insufficient empirical attention. We report on an applied experimental study investigating the impact of chronotype on the synchrony effect in a semantic analogy task. To detect an analogy, 36 participants (12 males) aged between 18 and 40 had to decide whether the relation between events of a source pair was mirrored by the relation between events of a target pair (e.g. to cook: to eat = to saddle: to ride). Temporal orientation of the relation within each event pair was varied corresponding either to the chronological or reverse order. Response times (RTs), error rates, as well as the psychophysiological parameters pre-experimental pupil baseline and peak pupil dilation replicate findings of a synchrony effect (shorter RTs and allocation of less cognitive resources at optimal times of day) and show an impact of chronotype (morning types generally outperforming evening types). Most importantly, morning types appeared to cope better with the synchrony effect than evening types: At suboptimal times, morning types solved the analogy detection task more efficient; that is faster with the same accuracy and without the investment of more cognitive resources. They also showed greater alertness and wakefulness indexed by greater pre-experimental pupil baselines. At optimal times of day, morning types have more cognitive resources available to allocate these to the more demanding conditions to outperform evening types. We interpret these findings to suggest that morning types are more able to adapt to unfavourable circumstances (for instance, by avoiding wasteful resource allocation when there are less cognitive resources available). Evening types appear less able to adapt to suboptimal times than morning types, because they have to deal with social jetlag and decreased self-control.

KEYWORDS:

• Morningness/eveningness
• pupillary response
• time succession
• cognitive resource allocation
• social jetlag

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Notes

¹ Independently from time of testing and chronotype, we expected analogy items to be identified more easily than distractor items (i.e. with one pair of events being presented in a chronological order, the other in a reverse order) as well as chronologically presented semantic analogies to be detected more easily (i.e. faster, lower error rates and lower peak pupil dilation) than reversely presented semantic analogies.

² To avoid type I and type II errors, Bortz and Döring (2006) suggest 36 participants as optimal sample size for repeated measures ANOVA to have 80% power for detecting a medium sized effect when employing the traditional .05 criterion of statistical significance. This was supported by a priori power analysis using GPOWER 3.1 (Faul et al. 2007), which indicated that a total sample of 34 participants was needed for the same power measurements. For correlational analyses, a priori power analysis indicated that a total sample of 36 participants and a 80% power would be sufficient for detecting a medium to large sized effect when employing the .05 criterion of statistical significance.

³ Independently from time of testing and in line with previous research, we found significant main effects of analogy condition and/or temporal orientation of items on RTs, error rates and peak pupil dilations. Analogy items (M = 7000.43 ms, SE = 387.72 ms) were identified faster than distractor items (M = 7336.94 ms, SE = 435.92 ms; F(1,34) = 8.56, MSE = 262 141.21, p = .006, η² = .201); chronological analogies (M = 6441.21 ms, SE = 391.17 ms) were processed faster than reverse analogies (M = 7559.65 ms, SE = 394.72 ms; F(1,34) = 87.86, MSE = 268 565.60, p < .001, η² = .721). Chronological analogies were detected with lower error rates (M = 9.72, SE = 1.51) than reverse analogies (M = 18.67, SE = 2.16; F(1,33) = 20.63, MSE = 69.91, p < .001, η² = .371). Regarding peak pupil dilation, identifying distractor items led to smaller peak dilations (M = 0.142 mm, SE = 0.018 mm) than identifying analogy items (M = 0.080 mm, SE = 0.021 mm; F(1,33) = 21.88, MSE = .003, p < .001, η² = .385). Identifying chronological analogies (M = 0.105 mm, SE = 0.021 mm) led to smaller peak dilations than identifying reverse analogies (M = 0.179 mm, SE = 0.028 mm F(1,33) = 14.25, MSE = .007, p = .001, η² = .289).

Additional information

Funding

This work was supported by the Elsa-Neumann-scholarship: Berlin, Germany, NaFöG.;