SUBTLEX frequencies are a powerful predictor of number processing speed

Our colleague Ineke Imbo recently used the SUBTLEX-NL word frequencies in her research on number processing and found that the SUBTLEX-NL frequencies for the numbers 1-99 are the most powerful predictor of their naming latencies.

Table: Correlation between number naming latencies and several frequency measures. All frequency measures were log transformed.

SUBTLEX-NL number frequencies (Keuleers, Brysbaert, & New, 2010) SUBTLEX-NL number word frequencies (Keuleers, Brysbaert, & New, 2010) GOOGLE number frequencies (Verguts & Fias, 2006) ESTIMATED number frequencies (Gielen et al., 1991)
Dutch Naming Latencies (L1) -.537 -.518 -.513 -.427
English Naming Latencies(L2) -.609 -.642 -.539 -.570

Twenty students at Ghent University (Belgium) (sixteen females, four males; mean age 19.7) named all numbers from 1 to 99 in two blocks. In one block they named the numbers in Dutch (L1) and in the other block they named the numbers in English (L2). Each number was presented four times per block. A trial started with a fixation point (500 ms), after which the number was presented in Arabic digits. Timing began when the stimulus appeared and ended when the participant’s response triggered the sound-activated relay. Invalid trials due to naming errors or faulty time registration were removed. The table below shows the correlations between the Dutch and English naming latencies, on the one hand, and the different frequency measures, at the other hand. The log-transformed frequencies from the SUBTLEX-NL database turn out to correlate best with the observed naming latencies – and this is true for both languages (L1 and L2).

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