Word frequency in fast priming: Evidence for immediate cognitive control of eye movements during reading

Abstract

Numerous studies have demonstrated effects of word frequency on eye movements during reading, but the precise timing of this influence has remained unclear. The fast priming paradigm was previously used to study influences of related versus unrelated primes on the target word. Here, we use this procedure to investigate whether the frequency of the prime word has a direct influence on eye movements during reading when the prime–target relation is not manipulated. We found that with average prime intervals of 32 ms readers made longer single fixation durations on the target word in the low than in the high frequency prime condition. Distributional analyses demonstrated that the effect of prime frequency on single fixation durations occurred very early, supporting theories of immediate cognitive control of eye movements. Finding prime frequency effects only 207 ms after visibility of the prime and for prime durations of 32 ms yields new time constraints for cognitive processes controlling eye movements during reading. Our variant of the fast priming paradigm provides a new approach to test early influences of word processing on eye movement control during reading.

Keywords:

• Eye movements
• Reading
• Fast-priming
• Word frequency
• Distributional analyses

We thank Ralf Engbert, Reinhold Kliegl, and the Deutsche Forschungsgemeinschaft, grant no. [FOR 868], Research Unit “Computational Modelling of Behavioural, Cognitive, and Neural Dynamics”, for financial support to DJS and SR which enabled them to undertake a research visit to UCSD. The research was also partially supported by grant [HD26765]. This work had its origins in the time when KR was an Alexander von Humboldt Visiting Professor at the University of Potsdam and was implemented when DJS and SR were visiting researchers at UCSD. We thank Daniel Lee for assistance with the creation of the text material. We thank Eyal Reingold for his helpful comments on the manuscript.

We thank Ralf Engbert, Reinhold Kliegl, and the Deutsche Forschungsgemeinschaft, grant no. [FOR 868], Research Unit “Computational Modelling of Behavioural, Cognitive, and Neural Dynamics”, for financial support to DJS and SR which enabled them to undertake a research visit to UCSD. The research was also partially supported by grant [HD26765]. This work had its origins in the time when KR was an Alexander von Humboldt Visiting Professor at the University of Potsdam and was implemented when DJS and SR were visiting researchers at UCSD. We thank Daniel Lee for assistance with the creation of the text material. We thank Eyal Reingold for his helpful comments on the manuscript.

Notes

¹ To improve generalizability of our findings, we refit all statistical models without removing non-significant random effects, including random slopes for main effects, interactions (where present), and random correlations; cf., Barr et al., 2013. Based on these random effects structures, from a total of 12 significant GLMM-tests of prime frequency effects reported in the present study, nine effects remained significant (including all effects for SFD, TRT, and second and later fixations), two were marginal (for gaze durations and regressions), and only one post-hoc test (for gaze durations) turned non-significant, clearly supporting the reliability of the present findings.

² We performed several control analyses to further check the validity of these post-hoc analyses involving the prime duration factor. We ran several control models for five dependent variables of interest (SFD, GD, TRT, second and later fixations, regression probability). First, to check whether effects of prime duration are confounded with potentially correlated oculomotor factors, we statistically controlled for the oculomotor variables target word landing position (linear and quadratic), incoming saccade amplitude and pre-boundary fixation duration by adding these covariates to the (G)LMMs reported above. Next, the median prime duration of 28 ms occurred very frequently in the data (see Figure 1). To avoid a decision on a cut-off below or above the median, we created a 3-level factor coding prime durations <28 ms, = 28 ms, and >28 ms, and tested the interaction of prime frequency with this 3-level factor via likelihood ratio tests. We tested additional models combining the 3-level factor with the oculomotor covariates and, last, added higher-level interactions between the oculomotor covariates and prime frequency. In total, we thus performed four control analyses for each of the five dependent variables. The results from these analyses supported our overall findings, as the interaction between prime frequency and prime duration was significant or marginal in 17 out of these 20 tested control models.